WEST NILE VIRUS

(Documents are in order, from the most recent one to the oldest one)

_______________________________________________________-

4-29-04    (Regarding the message from Rob Callen DVM dated 4-28-04)

 

Thanks for the update and reminder that it's important for everyone to do
early and aggressive mosquito control.

I went looking around for the Vectobac or Aquabac larvicide in corn cob
granular form for distribution of the Bacillus thuringiensis, var.
israelensis for mosquito larvicide control.  I also visited the site you
referenced for purchasing the material and read up on the MSDS sheets from
the manufacturers.

From that information I noticed that there are distinct versions of this
larvicide, some of which are intended for Canadian only use and some for USA
only use.  I don't know what the difference is, but they do denote a
different licensed product for each country. 

The site you pointed everyone to sells the Canadian version.  So I don't
know if you can purchase and import it from the purchaser you referenced
since it's not EPA licensed.  You many want to inform everyone that there's
a distributor of the Vectobac/Aquabac for USA usage at:

http://www.e-adapco.com/

That may be a better and more correct source for this larvicide (and looks
like it's cheaper than the site in Canada).

With regards
Stephen & Shari Quackenbush
Bar-Q-Diamond Ranch
5555 E. Willow Creek Road
Castle Rock, CO 80104
Tel. 303-688-6662
email.  llamas@bar-q-diamond.com
http://www.bar-q-diamond.com

__________________________________________________

4-28-04

At a meeting we had here on mosquito control, the speaker talked about a granular formulation of the Bacillus thuringiensis israelensis (Bti).  Vetctobac is a granualar product that can be applied directly to fields or marshy areas where standing water is likely to exist for mosquito larva development as well as ponds.  The recommendation is to begin spreading this in susceptible areas now and then again later in the summer.  The goal is to reduce the overall buildup of mosquitoes early, thereby reducing total numbers as summer progresses.  The product is activated by water so it can be spread now if the area is dry and will then become effective when it rains and there is standing water.  

Below is an additional web site and a source.  If you think it is appropriate, could you please distribute this information to the alpaca and llama organization members.

http://www.nyc.gov/html/doh/html/wnv/wnvfaq8.html

http://www.actionintegration.com/cgi-bin/nic/getprod.cgi?10BT


Robert J. Callan, DVM, MS, PhD, DACVIM
Colorado State University
Department of Clinical Sciences
Food Animal Medicine and Surgery
970-297-0323
rcallan@colostate.edu
_________________________________

3-29-04
In an extended conversation with Dr. Rob callan today, we discussed the
culex tarsalis (that nasty little bugger which is the main vector of WNV
in the Rocky Mountain area).  Findings from last year indicate this type
of mosquito breeds at elevations to 8000 feet and feeds up to 10,000 feet.

Our members in the high country may wish to consider this in respect to
any vaccination protocol.

teri nilson baird

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Apr 24, 2004
West Preparing for Return of West Nile
 
 Apr 24, 5:25 PM (ET)

By DAN D'AMBROSIO
 
DELTA, Colo. (AP) - Insects are shaking off the winter cold in the West, promising another season of the West Nile virus, the mosquito-borne killer that has infected thousands of people - killing 564 of them - since the first domestic case turned up in New York in 1999.

For two-thirds of the country, the crisis has largely passed. But in the West, health officials are drawing up battle plans from the apple orchards of western Colorado to the California coast.

Carried by birds bitten by infected mosquitos, the incurable virus hasn't yet hit the West hard, except in Colorado. But few states are waiting.

Wyoming has earmarked $1.7 million for mosquito-control programs, up from $387,000 last year. Arizona officials have doubled their budget.

California mosquito districts began work earlier than usual this year and in expanded areas. Sentinel flocks of chickens - which can be easily tested for infection to determine the virus' spread - were tested through the winter and the virus was found for the first time in Ventura County earlier this year.

On the western slopes of the Rockies, there is a fear that Colorado could again be ground zero after leading the nation last year with 2,947 of 9,858 overall cases - and 61 of the year's 262 deaths.

Keith Lucy, an environmental health officer in this western Colorado town, and mosquito control officer Jim Terrazas, recently inspected a marsh behind a park popular with the locals for picnics and fishing. Half the marsh is owned by a man who doesn't want mosquito control officers on his land. The owner of the other half, however, has given his consent for the use of larvicide, which kills soon-to-be mosquitos.

That places Terrazas in a dilemma. What good does it do to treat only half the water?

"It's a waste of taxpayer money," he said.

Lucy moves on to the Escalante State Wildlife Area along the Gunnison River, where officials would like to flood the banks to help two endangered species of fish spawn. That raises the possibility of more standing water - prime breeding ground for mosquitoes.

Not only that, wildlife area manager Mike Zeman won't allow adulticide - a pesticide designed to kill adult mosquitoes that is often spread as clouds of machine-generated fog - on the 7,500-acre refuge.

"Fogging is non-selective," he said. "You're hitting all kinds of insects and we have all kinds of birds who feed on those insects."

Lucy looks a little stunned. "The thing here is their primary focus is on wildlife habitat, but mosquitoes breed here and they don't stay here," he said.

Killing adult mosquitoes also can mean spraying with Malathion, a toxic chemical known to cause illness and genetic mutations.

Last year, residents of nearby Paonia protested a plan to spray the chemical and someone bombed a warehouse where Malathion was stored. No one was injured.

"It was a not so subtle message that this is not the way you want to control mosquitos here," Lucy said. "That's the dilemma we're in."

Lucy and his colleagues also are constrained by a budget of just $25,000.

"You get as much public health as you want to buy," said Bonnie Koehler, the deputy director of the Delta County health department. "If you want to give me a hundred thousand dollars, I can give you the George Lucas mosquito control plan the likes of which you have never seen."

Fifty miles away in Grand Junction, crews will soon begin dropping cork-shaped larvicide "briquettes" through more than 3,000 city storm grates. They'll have to revisit the drains every month through October. Larvicide also will be spread in city ponds, practice fields and parks where watering creates pools of water, golf course ponds, and pastures and farmland.

Steve DeFeyter, the Mesa County environmental health director, will trap mosquitoes and sample catch basins in Grand Junction for larvae to determine how well the war is going.

He also has laid the groundwork for an adulticide campaign, if necessary.

"Nobody wants to get into that because it raises such controversy," DeFeyter said. "But if it gets to a public health emergency, then it's the only option you have left to protect the public health."

CDC: http://www.cdc.gov/ncidod/dvbid/westnile/index.htm
 
 
 ___________________________________________________-----
 3-13-04

West Nile Virus Vaccination in Llamas and Alpacas

Robert J. Callan, DVM, MS, PhD, DACVIM

Department of Clinical Sciences

Colorado State University

 

            We have received numerous inquiries regarding how to prepare for West Nile Virus (WNV) in 2004 and specifically, how to approach vaccination from the standpoint of safety, efficacy, and economics.  These are difficult questions to answer as there is limited information that specifically addresses disease risk and vaccination in llamas and alpacas.  Based on the many reports from private practitioners and our experience at the CSU Veterinary Teaching Hospital, we know that both llamas and alpacas are susceptible to WNV infection and disease.  While there is no specific data available, the reported frequency of confirmed and suspected cases in alpacas seems to be higher than llamas.  Thus, it could be inferred that alpacas are more susceptible than llamas to clinical disease.  The first Colorado case (human) of WNV in 2003 was in early June.  The first alpaca case of WNV seen at CSU in 2003 was in mid August and the last confirmed case at CSU was near the end of September.  In the near future, we will be sending out a questionnaire to llama and alpaca owners to try to ascertain more detailed information relative to WNV disease in Colorado during 2003.

            As with other vector borne infections, WNV disease is best prevented by control of the vector, in this case mosquitoes, and stimulating immunity in susceptible animals.  With most contagious diseases, establishing 70% to 80% herd immunity will successfully limit clinical disease from spreading among susceptible animals.  However, in the case of WNV, individual immunity is much more important than population immunity because the reservoir hosts are birds and mosquitoes.   Because of this, a susceptible non-immune animal is just as likely to become infected whether 0% or 99% of your herd is immune.   Therefore, when we are looking at WNV vaccination programs we want to do our best to ensure that EVERY animal has sufficient immunity during the critical period of seasonal exposure.

            There are currently two commercial vaccines licensed for use in horses.  One is a killed virus vaccine (Innovator, Fort Dodge Animal Health) and the other is a recombinant canarypox DNA vaccine (Recombitek, Merial).  The Fort Dodge Animal Health (Innovator) vaccine has been administered to llamas and alpacas but use of this vaccine must still be considered with appropriate caution.  Studies by Dr. David Anderson at Ohio State University and Dr. Michelle Kutzler at Oregon State University suggest that this vaccine is safe in llamas and alpacas and will stimulate a humoral antibody response following three intramuscular injections given 30 days apart.  The Merial canarypox DNA vaccine incorporates WNV membrane and envelope proteins into the canarypox DNA and expresses these proteins following administration.  The method of antigen expression with the canarypox vaccine would suggest stimulation of both humoral (antibody) responses and cytotoxic T-cell responses believed to be important in both the prevention and clearance of WNV infection.  No safety or efficacy studies of the Merial canarypox DNA vaccine have been performed in llamas or alpacas.  We are working with Merial and the Colorado llama and alpaca industry to perform a safety and seroconversion study with the canarypox DNA vaccine prior to Spring 2004.  Efficacy studies in horses show that both vaccines provide effective prevention of viremia following experimental challenge.  While challenge studies have not been performed in llamas or alpacas, it is believed that the immunity induced by these vaccines will help reduce the incidence and severity of disease in these species. 

            Last year, anaphylactic-like reactions were described in two alpacas from Colorado that were vaccinated with the Fort Dodge Inovator vaccine.  While both animals survived, this observation highlights the potential for adverse reactions when administering any vaccine to any animal.  Because of the importance of monitoring adverse vaccine reactions, owners and veterinarians are strongly encouraged to report any adverse vaccine reactions to Fort Dodge Animal Health and the USDA Center for Veterinary Biologics by visiting the Adverse Event Reporting web site at http://www.aphis.usda.gov/vs/cvb/ic/adverseeventreport.htm or by calling 800-752-6255 .  You may also send reports of WNV vaccine reactions to me by email (rcallan@colostate.edu) so that we can keep all Colorado camelid producers informed as further information is reported.

While there is significant latitude in how you administer any vaccination program, the following guidelines should help those of you planning to vaccinate your animals for WNV this year.

 

       Non-Vaccinated Adult Animals

o      Administer 3 intramuscular doses at 3-5 week intervals.

o      Begin vaccination in March or April so that the animals will have antibody titers by the start of WNV season.

o      As with any vaccine, inflammatory responses induced by vaccination can adversely affect pregnancy.  If possible, avoid vaccinating breeding females within 60 days of breeding or within 30 days of parturition.

       Previously Vaccinated Adults or Adults With Confirmed WNV Titers

o      Administer a single booster vaccination in May or June.

o      As with any vaccine, inflammatory responses induced by vaccination can adversely affect pregnancy.  If possible, avoid vaccinating breeding females within 60 days of breeding or within 30 days of parturition.

o      At this time, there is no indication that animals will need an additional booster in the middle of the WNV season.  However, some owners and veterinarians may want to consider an additional booster in August to provide higher immunity during the peak WNV months of September and October.

       Neonates

o      Administer 3 intramuscular doses at 3-5 week intervals.

o      Strategically vaccinate prior to the onset of WNV season when possible.

o      If the dam was vaccinated or has a confirmed WNV titer, start vaccination after 3 months of age or later depending on the season.

o      If the dam was not vaccinated and/or has a negative WNV titer, start vaccination at 1 month of age or later depending on the season.

 

Due to the expense of the WNV vaccine, some veterinarians and producers have suggested screening the herd for antibody titers prior to vaccinating and only giving the three dose vaccination regimen to animals with negative titers.  WNV titers can be determined by collecting a blood sample from the animal and sending it for a WNV Microtiter Serum Neutralization Test (Cornell Veterinary Diagnostic Laboratory) or a Plaque Reduction Neutralization Test (National Veterinary Services Laboratory).  This is a reasonable strategy but it must be emphasized that even if a large proportion of a herd has antibody titers, the seronegative animals still need to receive a full three dose series in order to be protected.  Otherwise, you will still have individual animals that are susceptible to infection and disease.

The most complete screening and vaccination recommendation is to test a portion of your herd (i.e. 10 animals or 10%) to determine an estimate of the prevalence of seronegative animals.  From that information, you can evaluate the economics of whether you should just vaccinate all animals with three doses, or test all animals and vaccinate the seronegative ones with three doses and the seropositive ones with just a single dose.  We have received several inquires as to how to apply this process and at what seropositive prevalence does one decide whether or not to vaccinate all animals with three doses or test the remaining herd and vaccinate based on titer.  Basically, this is an economic decision where you need to decide which is less expensive, to test and differentially vaccinate or to simply vaccinate all animals with three doses.  The basic economic model indicates that one should simply vaccinate all animals with 3 doses of vaccine if the prevalence of seropositive animals is less than the cost of testing divided by the cost of a single vaccination dose.

 

Vaccinate All Animals with 3 Vaccine Doses IF:

P< T/2V where:

P = Estimated prevalence of seropositive animals based on your herd screening

T = Test Cost per animal including supplies, veterinary charges, labor, and postage

V = Vaccine Cost per dose including vaccine, supplies, veterinary charges, and labor

 

You should work with your veterinarian to determine the specific costs of testing and vaccination in your herd but in general, it is less expensive to simply vaccinate all animals unless the prevalence of seropositive animals in the herd is expected to be greater than 75%.  Because of the need to test at least 10 animals to get an accurate estimate of the prevalence of seropositive animals, the break even prevalence becomes higher for herds with less than 100 animals.  Even after last year, it is unlikely that many herds have a seroprevalence higher than 75% unless they were in a high endemic area.  Thus, it seems that simply vaccinating all animals with three doses is the most economical protocol to adopt for the average herd.

The last consideration is the point where potential economic loss from disease becomes less than the cost to vaccinate.  Based on very limited information, our best estimate at this time is that approximately 10% of infected non-vaccinated alpacas become ill with a case mortality rate approaching 50%.  In an endemic area, the infection rate may approach 50% and you might expect 1 in 20 animals to become sick and perhaps 1 in 40 animals to die from WNV.  Very few areas of Colorado saw this level of infection last year.  Assuming a 50% infection rate in an endemic area, the estimated cost of WNV is 2.5% (0.5 infected x 0.1 cases per infection x 0.5 case mortality) the average value of the animals plus veterinary expenses.  Some producers may take the approach that aggressive vaccination of the entire herd is not warranted and will accept some losses from this disease.  In general, vaccination of animals is economically warranted if the cost of vaccination is less than the potential savings from preventing the disease through vaccination.  For example, if we make the assumption that the vaccine will prevent disease in 100% of infected animals, then the average return on vaccination is the average cost of disease per susceptible animal.  It is estimated that in an endemic area the average cost of disease per susceptible animal in a herd is $275 based on conservative figures relative to the value of individual animals and the cost of treatment.  In this case, you can see that three doses of vaccine and/or annual boosters are economically prudent.  The vaccination break even point occurs when the economic value of the animal is $1400 in an endemic area.  This break even point decreases if the cost of vaccination, the value of an individual animal, the cost of treating a sick animal, or the incidence of WNV infection is lower.  Thus vaccination may not be economically warranted under many circumstances.

Hopefully this discussion will give you some useful information to help decide how to approach WNV vaccination.  You should work closely with your veterinarian to determine if WNV vaccination is appropriate for your herd.  If you have further questions, please consult with your local veterinarian or feel free to contact the veterinarians at CSU.

 


____________________________________

September 19, 2003
This West Nile information is being released as part of the Emergency Medical
Alert and Notification system primarily for North American camelid owners.

As many of you know, the high desert, western and mountain areas of the United
States are currently associated with a growing West Nile virus outbreak. In
addition, there are other spotty outbreaks. Hundreds of human cases have occurred
with many hospitalizations and some deaths. Network television recently
reported "significant alpaca deaths due to West Nile virus" in Colorado. This
has fueled misinformation both regarding susceptibility of alpacas to the disease
and has unnecessarily caused concern that alpacas may be "spreading the disease."
Both are incorrect.

However, veterinarians in the heavily afflicted areas are frantic with calls from
concerned camelid owners and are incredibly busy treating actual cases and
potential infections. Due to the workload, they have not had the time to
research the Internet or to call other colleagues to discuss promising clinical
treatments, recent developments and other relevant information.

To this end, we are posting website, telephone, fax, and e-mail for contacting
academic veterinarians who have significant experience with this disease. We are
not listing the many superb non-academic veterinarians with West Nile experience
as we recognize that many of these field clinicians are so busy treating actual
cases. The contact information may be passed on to your local veterinarian.

We will soon be posting a web-site URL so that veterinarians and other interested
individuals can access the latest information through the International Camelid
Institute (ICI). The URL for the ICI site is  http://www.icinfo.org  (double click
on the blue text to automatically go there). It will soon have links to the
camelid emergency medical alert and notification system.

In addition, the Alpaca Research Foundation (ARF) has updates
http://www.alpacaresearchfoundation.org  as well as the Rocky Mountain Llama & Alpaca 
Association (RMLA)  http://www.rmla.com/west_nile_virus.htm   which has very
recent communications on outbreaks.

Here is a list of contact information for you and your veterinarian.

Ohio State University:
Dr. Miesner, DVM and International Camelid Institute
Emergency Cell Number: (614) 403-1016
Fax (614) 292-3530
Dr. David Anderson Emergency Contact Number: (614) 403-1017
e-mail for Dr. Anderson anderson.670@osu.edu
Veterinary Hospital (24 hour): (614) 292-6661, ext 10 (large animal)

Colorado State University
Dr. Van Metre, DVM
Dr. Callan, DVM
Telephone: 970-221-4535
Fax: (970) 491-4100

Oregon State University
Telephone: (541) 737-2858
Dr. Chris Cebra
Telephone: (541) 737-2858
E-mail: christopher.cebra@oregonstate.edu

Dr. Michelle Kutzler, DVM
Telephone: (541) 737-6952
E-mail: michelle.kutzler@oregonstate.edu

(Information from Alpaca Owners & Breeders Assn.)

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9-12-03

I recently had a 2 year old female alpaca who had given birth the month before present to me in lateral recumbency exhibiting convulsions and the inability to rise of less than 2 hour duration.  Aggressive anti-inflammatory treatments failed to reverse the signs and the animal died less that 24 hours from the time the owner noticed the problem.  Blood work was consistent with a viral infection.  Brain tissue was submitted and confirmed positive for WNV by PCR.  Histopathology on the tissue showed a nonsuppurative encephalitis consistent with viral infection.  Another female alpaca had died 2 weeks earlier with similar signs but was not tested.  This animal had been in labor for 2 days and died soon after delivering her cria.  We treated the cria for the last 3-4 weeks but it too progressed to convulsions and inability to rise.  Despite treatment, it too expired.  We did submit brain from the cria for testing and histopath results have confirmed a nonsuppurative encephalitis consistent with a viral infection.  We are awaiting PCR test results.  My clients requested I send this information to you for your distribution.  I feel early detection is key with aggressive anti-inflammatory therapy.  Stay in touch with your veterinarian and notify them of any abnormalities.  One farm in our area has vaccinated their 15 animals against WNV with the equine vaccine with no adverse reactions.  I feel the decision to use this vaccine is an individual one and you should consult your veterinarian to discuss the options.  I hope this information will increase the knowledge of this emerging disease in camelids.  
 
Sincerely,
Eric E. Chapman, DVM

Montezuma Veterinary Clinic in Cortez, CO.

chapmaneric@hotmail.com

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9-10-03

A breeder in Durango, CO lost a Stud/Pack llama to West Nile.  Blood tests done by Cornell University confirmed this yesterday, 9-9-03.  The breeder has another suspicious WNV case, now being tested.

WNV now appears to be on the West Slope of Colorado.

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9-1-03

One of the two in Elbert was euthanized tonight (Sep. 1)- we don't have
confirmation by PCR yet - but he showed similar clinical signs as the other
animals - the 5th animal is hanging in there but has developed more tremors
and have difficulty eating.

Kimberly Gardner-Graff, DVM  (Dr. Kim)

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8-29-03

As many of you have heard rumored West Nile has come to our Southern Colorado Alpaca herds.
On Tuesday, August 19th I had 3 alpacas present with varied degrees of head / tremors.
The ages were for 1 year to 6 years of age - all in good health prior to developing the tremors - all from different areas.
 
Alpaca 1 was from the Kiowa area.  She started 4 days earlier with just mild tremors (Kathryn Hepburn type) and a fever of 103 degrees - by Monday evening she was stumbling with her front legs and full body tremors, Tuesday morning she was down, unable to use her front legs but continued to eat.  Wednesday afternoon she stopped eating and by that evening she was unable to lift or move her head.  Despite aggressive treatment with steroids, fluids, DMSO, nonsteroidal drugs and pain meds as well as anti-ulcer meds and force feeding she died Thursday morning.
Serology testing and PCR tests on brain tissue confirmed a West Nile infection.

Alpaca 2 - was from the area of Palmer Divide Road and Black Forest Road in El Paso  County.  She presented for wt loss over 4 days and abnormal spasms of her lips and eyes.  She was unable to control her lip movements and therefore unable to eat properly.  She was extremely agitated and the minimal stimulation would make her scream, and urinate. She was treated with the same medications as Alpaca 1 - by Friday she was weak but still able to stand but appeared unable or very reluctant to raise her head she also stopped eating on her own.  Saturday she was reluctant to stand, appeared very weak and would layin kush but unable to raise her head - her tremors decreased but would reappear with stimulation.  Sunday she began to improve- Monday she was spitting and standing with her head up but still would not eat on her own.  She died Tuesday morning.  Serology and PCR Tests are still pending but highly likely to confirm West Nile infection.
       One extra note on her - she did have a two month old cria that has shown no sign of disease as of this date.

       Alpaca 3 was from the Falcon area - She gave birth to a cria the Friday before.  Over the weekend she developed mild tremors that responded somewhat to Banamine. Tuesday morning she was stumbling with her front legs and not eating.  Tuesday night she was down on her side - unable to roll up or lift her head - she had full body tremors that made her appear to be seizing but she never lost consciousness.  Again - intensive IV fluid and anti-inflammatory therapy was started - she continued to progress and died Thursday morning.  PCR testing has confirmed West Nile infection.
       Added note; her cria was born blind with facial nerve paralysis on the left side it died 4 days after birth - PCR testing on the cria was negative for West Nile Virus.
 
       In the past week I have had two more alpacas with suspect West Nile infections- Both of these are from the area around Elbert.  Unlike the three animals listed above these three started with temps greater that 105 degrees - that could be controlled with Banamine - but within 72 hours have developed mild to severe facial tremors and twitches.  They are being treated as I write.  One is still eating the other has stopped - Serology on them is pending.

      The key to having any chance of a successful outcome is catching these animals early in the disease.  The treatment is very intensive and most likely will need to be continued for 7-10 days. Prognosis for animals early on the disease with mild facial tremors is poor - animals that are recumbent (down) is grave.    
       Monitor your animals closely - any animal that has a decrease in appetite or a new twitch or funny little vibration of the head, or any trouble walking or stumbling  should be examined immediately! Be vigilant about decreasing mosquito exposure.  Although, none of these farms have had a mosquito problem,
       I will keep you updated on their status and the development of new suspected cases in our area.
Sincerely - Dr. Kim Gardner-Graff

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8-22-03        Research Update:
Results of Three-Dose West Nile Virus Vaccine Testing  in Camelids at Oregon  State University

Dr. Michelle Kutzler, DVM, PhD, DACT; Mr. Rocky Baker, MS and Dr. Donald
Mattson, DVM, PhD, DACVD
College of Veterinary Medicine, Oregon State University, Corvallis, Oregon


Objective: To determine if immunization with a West Nile virus (WNV) vaccine
licensed for use in horses (West Nile-Innovator, Fort Dodge) induces a humoral immune response in camelids.

Methods: Eighty-four mature camelids were immunized with a
formalin-inactivated, commercial WNV vaccine. All animals received three
intramuscular (1-ml) vaccinations three weeks apart and 28 llamas
received a 4th vaccination three weeks after the 3rd. Blood samples were collected
prior to and three weeks after each vaccination and end-point virus
neutralizing antibody titers were determined from the sera.

Results: No local or systemic reactions to vaccination developed. No animals
developed virus- neutralizing titers following the first vaccination.
Seventy-nine and 100% of alpacas developed virus neutralizing titers three
weeks following the 2nd and 3rd vaccination, while 61, 93 and 96% of llamas
developed virus neutralizing titers three weeks following the 2nd, 3rd and
4th vaccination. The log-transformed mean titer for antibodies against WNV
significantly increased following the 3rd vaccination.

Conclusions: Vaccination with the WNV vaccine is safe in camelids and
virus-neutralizing antibodies develop after three vaccinations in all
alpacas and most llamas. Studies are in progress to determine how long virus
neutralizing titers persist in camelids. Insufficient information is
available at this time to determine how susceptible camelids are to WNV or
if vaccination will be effective at preventing clinical signs of WNV infection.

Acknowledgments: We thank Alpaca Research Foundation, Willamette Valley
Llama Foundation, Southwest Washington Llama Foundation for funding this
research. We also thank Fort Dodge for the donation of 240 doses of West
Nile-Innovator vaccine.

For information on additional research projects sponsored by the Alpaca
Research Foundation, please visit our web site at
www.alpacaresearchfoundation.org.
Research Update: Results of Three-Dose WNV Vaccine Testing  in Camelids
at Oregon  State University

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8-21-03  Mosquito Barrier     

www.mosquitobarrier.com or contact@mosquitobarrier.com

This is a very strong liquid garlic. Garlic has a natural sulfur which repels
insects. This product is being used by city governments for parks, golf
courses and schools

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8-19-03    Confirmation from Dr Rankin:

We have had our 3rd conformation by PCR on brain tissue  of Alpaca West Nile
out of the 4 that died in my area. The 4th was not tested. The treated
alpaca continues to get stronger 10 days after clinical signs.  Watch for
head tremors, shaking of neck and chest or head bent sideways in the middle.


Dr. Jeanne Rankin
Ponderosa Animal Hospital
Ft. Collins, CO

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Opinion from Dr. Leon Anderson, Elizabeth, CO:

8-19-03

My thoughts on West Nile (WN), Leon Anderson, D.V.M

Recent Developments as I know them from conversations with other
veterinarians in practice and at CSU:

One llama (Elizabeth area) and 5 - 6 alpacas (Larimer County) have
shown signs consistent with WN disease in the last 3 weeks.  The llama and
all but one of the alpacas have died or were euthanized.  Two were confirmed
to be WN positive and the rest have tests pending.

How do we test camelids for WN?
       Dead camelids:  PCR testing on brain tissue
       Live camelids:  Clinical signs, blood cell counts and cerebrospinal
       fluid analysis can help point toward, but not definitively diagnose
       WN disease

The Vaccine (My Opinion):
       Currently I would only consider vaccinating camelids in and around
       that area of Larimer County.

Although I believe the vaccine will help protect our camelids, I
still feel the risks outweigh the benefits in most cases.  We're talking
about a small number of animals in a small area and a vaccine that may or
may not protect and may or may not cause serious reactions in our camelids.
We're also talking about vaccinating pregnant females unless you're going to
leave them open for the 9 weeks it takes to do three initial vaccines needed
to boost and hold titers.  In addition there will be a considerable expense.

One Rule:

Be flexible.  As time goes by our plan will be adjusted and our confidence
we are doing the best we can for our camelids will grow.
-------------------------------------------------------

Sent from AOBA to all members    8-19-03

WEST NILE VIRUS IN ALPACAS: DO WE HAVE ANYTHING TO FEAR?

With the recent outbreak and spread of West Nile Virus (WNV) throughout the USA, there has been an increased interest in the dangers associated with this disease. There have been multiple confirmed cases of infections of birds and humans. There have been approximately 10 llamas and alpacas diagnosed as having the WNV in the U. S. All llamas and alpacas confirmed to be infected with the virus have died. Some alpacas suspected of having WNV have survived with supportive treatments, but these diagnoses can not be confirmed at this time - only suspected based on positive serum antibody titers to the disease.

Clinical signs: Depression, lethargy, decreased appetite, may or may not have fever, staggering, recumbency, seizures, coma, death.

Early treatment: Supportive care. Initially, non-steroidal anti-inflammatory drugs are used (e.g. banamine) but then steroids are initiated once bacterial infection has been ruled out (dexamethasone should not be used as this can cause damage tot eh camelid liver; rather, prednisolone should be used). Ulcer prophylaxis (e.g. gastrogard, carafate, etc). IV fluids as needed.

Diagnosis: serum antibody titers, CSF antibody titers, if dead - IHC on brain and spinal cord tissues.

Since there is a poor prognosis for treatment, the best hope for prevention is vaccination. Fort Dodge Animal Health has marketed a vaccine for WNV in horses, which is not labeled for use in llamas or alpacas. As with all vaccines utilized in the llama and alpaca industry, this would be considered extra label use. We hypothesized that the equine WNV vaccine would stimulate antibody production in llamas and alpacas. Two studies have been done using this vaccine. Dr. Kutzler at Oregon State University lead a research project funded by ARF and these results have been posted on the ARF web site (www.alpacaresearchfoundation.org). At Ohio State, we are in the second year of a two year study designed to determine the reaction to subcutaneous administration and to determine the antibody responses by this vaccine. To conduct this study, we used 12 llamas and 16 alpacas and each was given the vaccine per the dosing instructions on the label for the equine species (1 cc given 2 or 3 times, each dose given 3 weeks apart). Blood was drawn on Day 0, 7, 14, 21, 28, 35, 42, and 70. These were sent to National Veterinary Service Diagnostic Laboratory for virus neutralization (VN) assay. No VN titer was detected at any time point in 26 out of 28 llamas and alpacas. However, two camelids had a VN titer of 1:10 at a single time point a week after the initial dose. VN titers rose markedly only after the booster dose of WNV in the other 26 llama and alpaca. However, some VN titers had decreased to less than 1:10 by 10 weeks after the initial vaccination (7 weeks after booster). It would appear that the vaccine would need to be administered every 2 to 3 months during the high-risk period for contracting WNV (e. g. when mosquitoes are active). Additional testing is required to examine the prolongation of serum antibody titers.

Preliminary epidemiology study:

West Nile Virus antibody titers from alpaca herds that suffered a WNV death last year (confirmed by immunohistochemistry tests to be WNV) showed that 10% of the alpacas had antibodies (titers exceeding 1:100) to WNV! These preliminary results suggest that we only saw clinical signs in 10% of the infected alpacas. Thus, alpacas are relatively resistant to becoming infected (e.g. 1 in 10), and are relatively unlikely to develop clinical signs from the infection (e.g. 1 in 10). Additional testing is required to gain a better understanding of this disease!

These results are preliminary and need 1) more numbers and 2) more analysis.

At this time, we can conclude that WNV infection is uncommon if not rare in alpacas, that when they get infected they are relatively unlikely to develop fatal illness from the disease, but that when they do succomb to infection (presumably because their immune systems are compromised for some reason) the disease is often fatal. These statements are similar to what we see of WNV in humans.

YOU MUST DECIDE HOW MUCH RISK YOU ARE WILLING TO ACCEPT. YES, THE VACCINE CAN BE USED. YES IT SEEMS SAFE AND YES IT DOES STIMULATE ANTIBODY TITERS. HOWEVER, WE KNOW THAT IT TAKES A MINIMUM OF 21 DAYS (E.G. AT LEAST 2 DOSES OF VACCINE) AND PROBABLY 42 DAYS (E.G. AFTER 3 DOSES OF VACCINE) TO STIMULATE ANTIBODY CONCENTRATIONS SUFFICIENT TO BE PROTECTIVE.

This research needs more support. Donations to support Dr. Kutzler's study can be made through the Alpaca Research Foundation by visiting their website  www.alpacaresearchfoundation.org

Donations to the Ohio State study can be made directly to:

Susan Kelly
VCS Accounts Manager
601 Vernon L Tharp Street
Columbus, Ohio 43210

Make checks etc payable to the "OSU CAMELID WNV RESEARCH FUND"

We will keep you updated on the progression of the disease and research being done.

David E Anderson, DVM, MS, DACVS
Head and Associate Professor of Farm Animal Surgery
Director, International Camelid Initiative
Ohio State University
E-mail: Anderson.670@osu.edu

 

-------------------------------------------------------

8-18-03

Due to the publicity on Denver TV News about West Mile Virus
infecting Alpacas in the Loveland area it is time that we put
out a warning to our members.    RMLA Webmaster

---

I am passing on information from Cleon Kimberling (Extension Veterinarian).
He just talked with Wayne Cunningham (State Veterinarian) and there have
now been West Nile Virus deaths in Alpacas.  There were four that died out
of a group west of Loveland and one died in Elizabeth.

Ruth Willson               
Technology Unit Manager           
Cooperative Extension Service     
Colorado State University          

Check these websites for info:

http://www.fightthebitecolorado.com/

http://www.cdphe.state.co.us/dc/zoonosis/wnv/WNVREPORT.pdf

http://www.cdc.gov/ncidod/dvbid/westnile/surv&controlCaseCount03.htm

--------------------

8-18-03

The Elizabeth case was a 13-year old pack llama and when the owner took him to CSU
they said it was the 4th lama (no species differentiation and I don't know who the other people are) they've seen this year.  Prognosis not good when it hits as his was less than 12 hours from when he was fine until he had to be put down.

I'll be glad to keep up with Wayne Cunningham.  

Scary stuff.  

Keep the standing water away and report any neighbors who refuse.

Teri Baird



-------------------------------------------------------

7-1-03

 

Research Update:
Results of Three-Dose West Nile Virus Vaccine Testing  in
Camelids at Oregon  State University

Dr. Michelle Kutzler, DVM, PhD, DACT; Mr. Rocky Baker, MS and Dr. Donald
Mattson, DVM, PhD, DACVD
College of Veterinary Medicine, Oregon State University, Corvallis, Oregon


Objective: To determine if immunization with a West Nile virus (WNV) vaccine
licensed for use in horses (West Nile-Innovator, Fort Dodge) induces a
humoral immune response in camelids.

Methods: Eighty-four mature camelids were immunized with a
formalin-inactivated, commercial WNV vaccine. All animals received three
intramuscular (1-ml) vaccinations three weeks apart and 28 llamas received a
4th vaccination three weeks after the 3rd. Blood samples were collected
prior to and three weeks after each vaccination and end-point virus
neutralizing antibody titers were determined from the sera.

Results: No local or systemic reactions to vaccination developed. No animals
developed virus- neutralizing titers following the first vaccination.
Seventy-nine and 100% of alpacas developed virus neutralizing titers three
weeks following the 2nd and 3rd vaccination, while 61, 93 and 96% of llamas
developed virus neutralizing titers three weeks following the 2nd, 3rd and
4th vaccination. The log-transformed mean titer for antibodies against WNV
significantly increased following the 3rd vaccination.

Conclusions: Vaccination with the WNV vaccine is safe in camelids and
virus-neutralizing antibodies develop after three vaccinations in all
alpacas and most llamas. Studies are in progress to determine how long virus
neutralizing titers persist in camelids. Insufficient information is
available at this time to determine how susceptible camelids are to WNV or
if vaccination will be effective at preventing clinical signs of WNV
infection.

Acknowledgments: We thank Alpaca Research Foundation, Willamette Valley
Llama Foundation, Southwest Washington Llama Foundation for funding this
research. We also thank Fort Dodge for the donation of 240 doses of West
Nile-Innovator vaccine.

For information on additional research projects sponsored by the Alpaca
Research Foundation, please visit our web site at
www.alpacaresearchfoundation.org.
Research Update: Results of Three-Dose WNV Vaccine Testing  in Camelids at
Oregon  State University

------------------------------------------------------------------

6-30-03

The following information was provided by
Teri Nilson Baird Governmental Relations Committee.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The nice folks from Fort Dodge Animal Health (manufacturers of the only
current WNV vaccine) are putting on seminars throughout the country in
WNV moderate danger areas in order to educate the public (and
particularly the horse owners) about WNV vaccination, prevention, and
the virus itself.

I went down to Calhan in March for this seminar.

The sales rep from Fort Dodge had no idea how many other kinds of
animals had tested positive through some of the work done cross country,
particularly in Nebraska where the outbreak was so devastating to so
many different kinds of animals.  I showed him the Washington Post
article which listed so many varying species and he was pretty shocked.

He mentioned Ft. Dodge will still sell the vaccine only to
veterinarians, rather than through catalog stores, even though it no
longer must be administered by a veterinarian.  This was in response to
reports of parents in Louisiana vaccinating their children (!) with the
serum.

Regarding prevention, the best thing we can do now:  There is a fish
(minnow variety) called the gambusia which feast on mosquito larvae
which have proven to cut down on breeding mosquito populations.  You may
want to throw some of these into your ponds.  That failing, there is a
product called Mosquito Dunk which is an herbicide in a donut shape.  No
harm to any critters drinking out of the pond or trough you use it in,
although apparently horses do like to nibble on it.  No ill effects.
They also recommend spraying permethrin on horses in early evening and
keeping fans on in stalls at night to keep the air moving.  Horses
should be brought in as they seem to be so very susceptible.

On the county level, I was pleased that El Paso County is taking a very
proactive stance on water collection.
Ponds in the county rights of way or state ROW will be subject to the
mosquito dunk product (they'll just throw it in on their way by)
and make sure each pond is treated. 
The county will also be strictly enforcing their
trash and garbage ordinance.  A real threat is old tires.  They will be
making people dispose of them or drill drainage holes in each one.  They
would like all citizens to aggressively report violations.  It isn't
just an eyesore any more: it's a public health hazard.

They will also be testing all fallen birds this year as opposed to last
year.  The county's environmental public health rep said they're
planning on using a throat swab test which has shown good results as
opposed to lining up the cadavers at the CDC facility in Fort Collins
and waiting months for the results.  They admit now that it wasn't only
the crow relatives which were positive.  A researcher at Nebraska whom I
met at USAHA said that everything but fish there had tested positive.

I had a separate conversation with the hosting veterinarian, who does
treat some llamas and alpacas in his practice.  I suggested symptoms he
may want to watch for in these animals (the convulsions we've heard
described in each case).  He will be in touch with me should he see
anything suspicious.

Lastly, I have to tell you that despite the susceptibility of horses,
the ownership is woefully uneducated as to this disease.  They have
their heads in the proverbial sand and just say, well, I've never seen a
mosquito here so I am not going to vaccinate.  The llama and alpaca
community should be aware that although the probability of a camelid
contracting the disease is very small, the possibility of human
contraction is not.

El Paso County is suggesting an infection rate up to 1:150.  This is a
scary number and we all need to pay attention.  We don't have fiber to
keep the mosquitoes away.


The following is reprinted (courtesy of the Llama Letter from Willamette
Valley) from the mosquito.org website:

Mosquito Larval Control from,
www.mosquito.org/mosquito.html

More Information at:
http://www.fightthebitecolorado.com/


The most effective way to control mosquitoes is to find and eliminate
their breeding sites. Eliminating large breeding areas such as swamps or
sluggishly moving streams or ditches is a task for organized mosquito
control programs. Homeowners, however, can take steps to prevent
mosquito breeding on their property:

1. Destroy or dispose of tin cans, old tires, buckets, unused plastic
swimming pools or other containers that collect and hold water. Do not
allow water to accumulate in the saucers of flowerpots, cemetery urns or
in pet dishes for more than 2 days.
2. Clean debris from rain gutters and remove any standing water under or
around structures, or on flat roofs. Check around faucets and air
conditioner units and repair leaks or eliminate puddles that remain for
several days. Change water in birdbaths and wading pools at least once a
week and stock ornamental pools with top feeding predacious minnows.
Known as mosquito fish, these minnows are about I - 1-1/2 inches in
length and can be purchased or native fish can be seined from streams
and creeks locally. Ornamental pools may be treated with biorational
larvicides Bacillus thuringiensis subsp. israelensis (Bti) or methoprene
(IGR) containing products) under certain circumstances. Commercial
products "Mosquito Dunks" and "Mosquito Bits" containing Bti can be
purchased at hardware/garden stores for homeowner use. Recently, Zodiac
developed "Preventative Mosquito Control" (PMC) that kills developing
mosquitoes using insect growth regulator (IGR) technology. Like
"Mosquito Dunks", Zodiac's "Preventative Mosquito Control" can be found
at many home/garden stores.
4. Fill or drain puddles, ditches and swampy areas, and either remove,
drain or fill tree holes and stumps with mortar. These areas may be
treated with the above Bti or methoprene products also.
5. Eliminate seepage from cisterns, cesspools, and septic tanks.
6. Eliminate standing water around animal watering troughs. Flush
livestock water troughs twice a week.
7. Check for trapped water in tarps used to cover boats, pools, (hay)
etc. Arrange the tarp to drain water.
8. Check around construction sites or do-it-yourself improvements to
ensure that proper backfilling and grading prevent drainage problems.
 9. Irrigate lawns and gardens carefully to prevent  water from standing
for several days.
10. Ditches that contain stagnant water for a week or  longer can
produce large numbers of mosquitoes.  Report such conditions to a
Mosquito Control or  Public Health Office. Do not attempt to clear
ditches as they may be protected wetland.



Questions?
Please e-mail Teri at:
 teri@brokenwindmill.com



 

-----------------------------------------------------------

 

6-23-03

Dear Llama and Alpaca Enthusiasts,

As many of you know, we have been conducting an extensive study
regarding West Nile Virus (WNV)  in camelids. To date, we have completed
Phase I of the vaccine study and are in the midst of Phase II of the
vaccine study. Also, we are in the midst of the Epidemiology study.

To date, individuals and associations from around the USA and Canada
have given generously to support this research. We have raised
approximately $15,000 for this research of which I have allocated
$10,000 to the study of the vaccine and $5000 to the epidemiology study.
We still need financial support - $2,250.00 for the vaccine study and
$4,578.00 for the epidemiology study.

What are these donations buying you? Our preliminary finds include:

Phase I vaccine study:

With the recent outbreak and spread of West Nile Virus (WNV) throughout
Ohio, there has been an increased interest in the dangers associated
with this disease.  There have been multiple confirmed cases of
infections of birds and humans.   There have been 6 to 9 llamas and
alpacas suspected of having the WNV in the U. S.  All llamas and alpacas
known to be infected with the virus have died.  Since there is a poor
prognosis for treatment, the best hope for prevention is vaccination.
Fort Dodge Animal Health has marketed a vaccine for WNV in horses, which
is not labeled for use in llamas or alpacas.  As with all vaccines
utilized in the llama and alpaca industry, this would be considered
extra label use.  We hypothesized that the equine WNV vaccine would
stimulate antibody production in llamas and alpacas.  Therefore, we
designed this study to determine the reaction to subcutaneous
administration and to determine the antibody responses by this vaccine.
To conduct this study, we used 6 llamas and 8 alpacas and each was given
the vaccine per the dosing instructions on the label for the equine
species.  Then, half of these animals received a booster dose of the
vaccine 3 weeks following the first injection.  Blood was drawn on Day
0, 7, 14, 21, 28, 35, 42, and 70.  These were sent to National
Veterinary Service Diagnostic Laboratory for virus neutralization (VN)
assay.  No VN titer was detected at any time point in 13 out of 14
llamas and alpacas.  However, one llama had a VN titer of 1:10 at a
single time point a week after the initial dose. VN titers rose markedly
only after the booster dose of WNV in the ? llama and alpaca.  However,
some VN titers had decreased to less than 1:10 by 10 weeks after the
initial vaccination (7 weeks after booster). It would appear that the
vaccine would need to be administered every 2 to 3 months during the
high-risk period for contracting WNV (e. g. when mosquitoes are active).
Additional testing is required to examine the effectiveness of 3 dose
vaccination and prolongation of serum antibody concentration by
follow-up booster vaccination. This will be PHASE II.


Preliminary epidemiology study:

West Nile Virus antibody titers from an alpaca herd of 140 alpacas(one
of the two herds in Ohio that suffered a loss last year confirmed by
immunohistochemistry tests to be WNV) showed that 10% of the alpacas had
antibodies (titers exceeding 1:100)  to WNV! These preliminary results
suggest that we only saw clinical signs in 10% of the infected alpacas.
Thus, alpacas are relatively resistant to becoming infected (e.g. 1 in
10), and are relatively unlikely to develop clinical signs from the
infection (e.g. 1 in 10). Additional testing is required to gain a
better understanding of this disease! We are testing more alpacas and
will be testing llamas.

These results are preliminary and need 1) more numbers and 2) more
analysis.

We thank you for any assistance you can provide.



Sincerely,
David E Anderson, DVM, MS


--------------------------------------------------

2-20-03

 

PHASE I STUDY COMPLETE !!

EXTRALABEL USE OF AN EQUINE WEST NILE VACCINE IN LLAMAS AND ALPACAS

  P.Ramsey, D. Linden, and David E. Anderson.  Dept. of Veterinary Clinical
Sciences
College of Veterinary Medicine
The Ohio State University
  Introduction:    There have been 6 to 9 llamas and alpacas suspected of
having the WNV in the U. S., all of which have died.  Since there is a poor
prognosis for treatment, the best hope for prevention is vaccination.  Fort
Dodge Animal Health has marketed a vaccine for WNV in horses, which is not
labeled for use in llamas or alpacas.  We hypothesized that the equine WNV
vaccine would stimulate antibody production in llamas and
alpacas.  Therefore, we designed this study to determine the reaction to
subcutaneous administration and to determine the antibody responses to this
vaccine.

Materials and Methods: We used 6 llamas (1 pregnant) and 8 alpacas and each
was given the vaccine per the dosing instructions on the label for the
equine species.  Half of these animals received a booster dose of the
vaccine 3 weeks following the first injection.  Blood was drawn on Day 0,
7, 14, 21, 28, 35, 42, and 70.  These were sent to National Veterinary
Service Diagnostic Laboratory for virus neutralization (VN) assay.

Results: No VN titer was detected at any time point in 13 out of 14 llamas
and alpacas after the initial vaccination dose.  However, one llama had a
VN titer of 1:100 2 weeks after the initial dose. VN titers rose markedly
only after the booster dose of WNV (given 3 weeks after initial
dose).  However, VN titers had decreased to  1:10 by 10 weeks after the
initial vaccination (7 weeks after booster). The pregnant llama in the
study maintained her pregnancy (due in March 2003!).

Conclusions: The results of this study indicate that the WNV vaccine can
elicit an antibody response after 2 doses. However, It would appear that
this vaccine would need to be administered every 2 to 3 months during the
high-risk period for contracting WNV (e. g. when mosquitoes are active).

Summary statement: Although WNV appears to be an extremely low risk disease
for llamas and alpacas, some farms may wish to initiate a vaccination
strategy to attempt to prevent the disease. When specific farms choose to
vaccinate for WNV, this study indicates that vaccination should be timed
such that the initial dose and a booster dose have been done before the
vector season starts. Also, another booster dose given 10 weeks after the
first dose will likely be required to provide protection throughout the
vector season. Phase II of this study is underway (epidemiological study to
estimate "true risk") is underway but funding is still needed.
Tax-deductible donations can be sent to: David E Anderson, DVM, MS, 601
Vernon L Tharp Street, College of Veterinary Medicine, The Ohio State
University, Columbus, Ohio 43210. Make checks payable to: OSU Camelid
Research Fund.

David E Anderson, DVM, MS
Diplomate, American College of Veterinary Surgeons
Associate Professor of Surgery, Food Animal
601 Vernon L Tharp Street
College of Veterinary Medicine
The Ohio State University

VISIT OUR WEB-SITES:
         http://www.vet.ohio-state.edu/docs/ClinSci/camelid/index.html
         http://www.internationalcamelidinstitute.org

 

 

 

----------------------------------------------------------------------------------


WEST NILE VIRUS, MAMMALIAN HOST RANGE - USA
*****************************************
A ProMED-mail post
http://www.promedmail.org>
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>

Date: Wed 9 Oct 2002
From: Bill Johnston <wjohnston@adph.state.al.us>


Recent media reports have prompted many questions regarding West Nile virus
(WNV) infection in species other than birds, horses, and humans. As an "emerging disease" in the United States, WNV has clinical and health effects on various animal species and populations that have yet to be described or fully reported. The following information is offered on the current knowledge of WNV infection in other species.

It is currently believed that any type of bird or mammal may be susceptible to WNV infection, but very few species appear to develop clinical illness due to infection. Since entering North America in 1999, WNV has been reported in thousands of birds, horses, and humans (over
2768 people and 146 deaths, as of Wed 9 Oct 2002). Before this year, WNV infection had been reported in several bat species, chipmunks, gray squirrels, striped skunks, a rabbit, and 3 cats. Laboratory trials had indicated that cats would become viremic and ill, but that dogs were
relatively resistant to infection with WNV.

Serosurveys in New York following the 1999 outbreak revealed that 8-11 percent of dogs had antibody titers to WNV, but had not become ill. As WNV has moved across the country this summer, infection and illness have now been reported in a domestic sheep, a mountain goat, a dog, a 7-month-old wolf pup, a llama, and an alpaca. Serologically positive black bears and white-tailed deer have also been detected, but these animals did not develop clinical illness.

Some of the animals that became ill had another underlying health condition and/or a compromised immune system predisposing them to development of clinical disease. For instance, the one 8-year-old dog in Illinois was immune-compromised. From what is currently known, WNV does not appear to pose a significant health risk for species other than birds, horses, and humans. The extremely small number of cases in other species, the active surveillance conducted for the last 4 years, and reports from 42 states that have detected WNV suggest that most of these species are extremely resistant to developing clinical illness from
infection. There is also no current evidence that any of these species are capable of serving as a reservoir for the virus.

It is likely more cases in other hosts will be found as WNV enters and becomes established in new areas. As additional information becomes available, the relative health significance of WNV infection in these populations will become more clearly established.

--
Bill Johnston, DVM, DACVPM
State Public Health Veterinarian
Alabama Department of Public Health
wjohnston@adph.state.al.us>
Forwarded by:
David E Anderson, DVM, MS
The Ohio State University
         http://www.vet.ohio-state.edu/docs/ClinSci/bovine/index.htm
         http://www.vet.ohio-state.edu/docs/ClinSci/camelid/index.html
         http://www.internationalcamelidinstitute.org

 

------------------------------------------------------------------------------

 

1-21-03  Oregon State and Ohio State

Working Together to Investigate West Nile
Virus in Llamas and Alpacas

Michelle Kutzler DVM, PhD
College of Veterinary Medicine
Oregon State University
Corvallis, Oregon 97331
Phone: 541-737-2858
Facsimile: 541-737-8651
E-mail: michelle.kutzler@oregonstate.edu

David E Anderson, DVM, MS
College of Veterinary Medicine
The Ohio State University
Columbus, Ohio 43210
Phone: 614-292-6661
Facsimile: 614-292-3530
E-mail: Anderson.670@osu.edu


In recent years, West Nile Virus infection has been spreading westward from
the eastern USA. The WNV was introduced into the USA in the late 1990's and
has become a vital concern to the avian and equine industries. Although
rare, WNV may infected humans and can cause fatal encephalomyelitis. The
case fatality rate in humans infected with WNV is less than 5%. Many
species of mammals have been infected with WNV including cattle, sheep,
goats, llamas, alpacas, and camels but clinical disease is rare. In endemic
WNV countries, seropositive rates vary widely among ruminant species (e.g.
cattle, sheep, goats, camels, and water buffalo). Although seropositive
rates may approach 75 %, clinical WNV infection in ruminating species
appears infrequent. Llamas and alpacas are considered to be a low-risk
species. This assertion was based on preliminary data from the USA in which
approximately 1 clinically infected llama or alpaca has been documented for
each 1500 horses documented. However, several cases of fatal WNV have been
diagnosed in llamas and alpacas.

What is WNV?
West Nile Virus is a type of virus termed "Flavivirus".

Where does it come from?
West Nile Virus is endemic to North Africa. The virus is
ubiquitous in the Nile River Valley and epidemiological studies have shown
seroconversion in a large range of native species.

How is it spread?
Birds serve as the natural reservoir for WNV. Mosquitoes are the
most importrant vector for transmission of the virus. Horses are viremic
for a relatively short period of time but may remain viremic for a long
enough period to allow infection of the insect vectors. This does not seem
to occur in the ruminant species. The physiology of South American Camelids
(SAC's: llama, alpaca, vicuna, guanacoe) most closely resembles that of
ruminants. Thus, we anticipate that llamas and alpacas will not serve as a
reservoir for infection of herdmates and the insect vectors.

What species can become infected?
WNV is most pathogenic in avian species and horses. Humans and
other mammals can become infected but usually remain assymptomatic.
Serological surveys of sheep, goats, cattle, and camels indicate that up to
75 % of the population may have circulating antibodies to WNV and these
antibodies may remain detectable for at least 12 months after exposure.
However, clinical disease in these species is rare.

What are the clinical signs of the disease?
Clinical signs are variable in horses, but neurological signs are
most common. These signs include ataxia, recumbency, tachycardia,
tachypnea, seizures and death. At Ohio State University's Veterinary
Teaching Hospital, two cases of WNV infection in alpacas were diagnosed in
the fall of 2002. The infection progressed from head tilt and ataxia to
recumbency and seizures over a period of 72 hours. Death occurred within 96
hours despite intensive medical therapy.

How is WNV infection diagnosed?
A number of diagnostic tests have been developed. In living animals, the virus neutralization (VN) test is used to detect antibodies in the bloodstream and is not species specific. In horses, an ELISA test for the immunoglobulin type IgM specific to WNV has been developed. This test is specific to horses and can not be applied to ruminants or SAC's. In animals that have died, immunohistochemistry tests can be performed on frozen
tissues (e.g. brain, heart muscle, etc.).

What is the treatment for affected animals?
No specific anti-viral treatments are available for WNV. Clinical
management of infected animals is achieved through symptomatic treatment.
These may include anti-inflammatory drugs or steroids, IV fluids and
electrolyte therapy, physical therapy, and nutritional and environmental
management.

How can the disease be prevented?
The single most important tool in WNV prevention is elimination of
insect vectors. Since mosquitoes are the most prevalent vector, control
measures should include management practices to eliminate mosquitoes.
Mosquito control includes drainage of standing water sources, mowing
vegetation around ponds and lakes, and aerating water sources to decrease
mosquito larvae survival (e.g. mosquito larval survival is significantly
reduced if oxygen dissolved in water can be maintained above 400 ppm).

Is there a safe vaccine against WNV?
A killed virus vaccine has been developed for use in horses (Fort Dodge
Animal Health). The manufacturer's recommendation includes an initial
vaccination followed 3 to 6 weeks later by a booster vaccination. This
vaccine was recently tested for safety by Oregon State University where 70
male llamas and alpacas were inoculated and at The Ohio State University
where 14 female llamas and alpacas, including pregnant females, were
inoculated. These studies found no adverse reactions or abnormal health
events after the initial dose of the vaccine in adult llamas and alpacas.
The initial vaccine dose was not inflammatory and no adverse tissue
reactions could be found. In the Ohio State study, the booster dose 3 weeks
later stimulated a mild injection site swelling. The reaction was milder
and resolved faster than that typically seen after Clostridial vaccination.
No other adverse effects occurred.

Is there an effective vaccine against WNV?
The efficacy of the vaccine to stimulate antibody production is
variable. In studies at Ohio State University, no antibody response was
observed after a single dose of the WNV vaccine. After a booster dose,
given 3 weeks after the initial vaccination, serum titer rose dramatically
during the three weeks following the booster. However, serum titers had decreased
dramatically by week 10 (7 weeks after the booster). The results of this
study suggest that the WNV vaccine may stimulate immunity but that this
immunity may be short-lived. The efficacy of the vaccine against actual
infection with WNV has not been investigated and no data exists to
determine if these antibody concentrations will prevent or lessen the
severity of infection. However, the antibody response is appropriate for
this vaccine. Thus, the WNV vaccine likely can be administered safely to
llamas and alpacas, but no information is available regarding its efficacy
against natural infection or the frequency of vaccination required to maintain protective immunity. Oregon State University is currently studying a 3 dose protocol to attempt to gain greater and longer lived antibody concentration in the blood stream.

What about the Epidemiology of WNV?
The true risk factors for WNV in llamas and alpacas remain
unknown. Both Oregon State University and Ohio State Univerity are
gathering epidemiological data at this time. Oregon State University will
closely track the disease as it moves to the western USA. Ohio State
University will evaluate the effect of established WNV infection in the
environment on resident camelid populations. This data will reflect events
that occurred in 2002 as well as the progression of the disease throughout
2003.

Summary
West Nile Virus is a new disease in North America and can be
rapidly spread by mosquitoes. Although extremely unlikely, WNV may infect
llamas or alpacas. No information is currently available regarding efficacy
of vaccination against natural infection with WNV in llamas or alpacas.
Preliminary vaccination results warrant further investigation.
Prevention of WNV infection should center on elimination of risk factors
such as mosquitoes and environments conducive to mosquitoes. The issues
surrounding vaccination against WNV must be made on a farm-specific and
geographical basis. Discuss the risks and benefits of vaccination with your
veterinarian to determine if this is right for your herd.


10-2-02 

                  * * International Lama Relations Committee Animal Health Bulletin *
* West Nile Virus Update
We are now aware of several additional WNV suspicious llama and alpaca
cases that are being monitored and studied. While there is ongoing
investigation into the conditions of these animals, people are encouraged
to not assign definite labels until there is a definite diagnoses supported
by laboratory results. Until then, while we might have strong evidence to
believe that there will be a WNV diagnosis, it should be considered
presumptive, not definitive.
There is currently some ground work for WNV vaccine antigenic capability in
camelids being done which may require industry funding. We will continue
to report to you.
Symptoms possibly indicating WNV in camelids might be confused with those
exhibited in animals suffering from meningeal worm or lysteriosis, among
other diseases. Clinical symptoms of WNV may include "downer" lama
symptoms; contracture of the neck muscles; incoordination; lying down,
seizures; and vocalizing in pain. In the recent alpaca case, the animal
exhibited clinical signs for 3.5 days prior to death.
Should you see any of these signs in your lamas, immediately contact your
veterinarian for assistance and if appropriate, discuss the very specific
tests necessary to confirm WNV. It is also recommended your veterinarian
contact the National Veterinary Services Laboratory in Ames, Iowa regarding
WNV testing.
We would appreciate hearing from you should you experience any of these
problems at your farm as the ILRC is tracking WNV cases in camelids and
monitoring development of treatment regimes and vaccines to share with the
industry.

David E Anderson, DVM, MS

-------------------------------------------------------------------

9-19-2002  

               * *  ILRC Animal Health Bulletin * *   West Nile Virus

The Government Relations/Animal Health working group is now functioning
independently from ILR as the International Lama Relations Committee.   The
ILRC has been monitoring situations in which a llama is alleged to have
West Nile Virus in Mass and another involving an alpaca in the West and we
wanted to share with you this update.  Please pass on to your members and
mail lists.

The case of alleged WNV in a llama in Mass involved a llama that died in
June.  This is NOT a confirmed case of WNV as the case involved is one with
suspect serology, no post mortem conclusions and no confirmed clinical
diagnosis. A full investigation will take time and if done, may not ever be
scientifically conclusive.   Unfortunately, yesterday morning we received
confirmation from the Iowa State University Veterinary Lab that West Nile
Virus has been confirmed in an alpaca.  The clinical signs, lesions in the
brain and virus detection in the body tissues all support this was in fact
a case of WNV.  We also learned the lab has also recently confirmed WNV in
a sheep.  Both the alpaca and the sheep had been recently introduced to
their respective herds raising the question of whether stress was a
contributing factor to their development of clinical disease.

This is not a lama emergency situation and owners should not over react or
draw improper conclusions based upon news reports, chat lines, incomplete
or inaccurate science. There is insufficient information available at this
time to determine how susceptible camelids are to WNV or if this was an
exceptional case, though we obviously now know camelids are capable of
becoming infected with West Nile Virus.  It is recommended that extra
precaution and care be taken by camelid owners in high WNV risk areas to
reduce mosquitoes by draining sources of standing water and thereby
reducing places they lay their eggs and breed. The CDC further recommends:
                                                                            
       At least once or twice a week, empty water from flower pots, pet food
       and water dishes, birdbaths, swimming pool covers, buckets, barrels, 
       and cans                                                             
       Check for clogged rain gutters and clean them out                    
       Remove discarded tires, and other items that could collect water     
       Be sure to check for containers or trash in places that may be hard  
       to see, such as under bushes or under your home                      
                                                                         

We will continue to bring you any additional news on this and other
important animal health issues.   Please do not hesitate to contact us with
any questions.

Dan Goodyear:            Ph: 610-488-6666     email:   BALDAN@aol.com
Marsharee Wilcox:        Ph: 410-374-3783     email:
evllamas@bellatlantic.net
Teri Nilson Baird:       Ph: 303-646-4373     email:
teri@brokenwindmill.com
Karen Conyngham:   Ph: 512-328-8715     email:   72040.3361@compuserve.com
Susan Tellez:            Ph: 409-866-0247     email:   Sztellez@aol.com


August 10, 2002

-----------------------

WEST NILE VIRUS: ARE LLAMAS AND ALPACAS AT RISK?

We get a lot of questions regarding West Nile Virus and its potential danger
to llamas and alpacas.

Can animals become infected with West Nile Virus. The answer is yes. "Other
animals have also been found to be infected and have died from WNV. During
the year 2000, reports from the Eastern states found WNV infecting 58
horses, two bats, a domestic rabbit, a skunk, a cat, a gray squirrel, and a
chipmunk." Having said that, ruminant species, including llamas and
alpacas, have not been diagnosed with WNV. Llamas and alpacas fall into
that category and do not seem to be susceptible to WNV infection.

At this time, I do not see WNV as a threat to our llamas and alpacas. Thus,
I am not vaccinating for the disease. We have no way to know if the WNV
vaccine would have a damaging effect or protective effect in llamas and
alpacas because the vaccine was not developed for use in these two species.

Do you want to know more?

People and West Nile Virus. What should I know? See:
http://ohioline.osu.edu/wnv-fact/1003.html

I spend alot of time outdoors. What are my risks? See:
http://ohioline.osu.edu/wnv-fact/1002.html

Do birds carry or transmit WNV? See:
http://ohioline.osu.edu/wnv-fact/1000.html

What is the role of wildlife in WNV? See:
http://ohioline.osu.edu/wnv-fact/1006.html

I have horses. What should I do? See:
http://ohioline.osu.edu/wnv-fact/1007.html

For information about mosquitoes and control, please visit this web site:
http://ohioline.osu.edu/b641/index.html

I am a veterinarian. WHat should I know? See:
http://ohioline.osu.edu/wnv-fact/1005.html

I am an MD. What should I know about WNV? See:
http://ohioline.osu.edu/wnv-fact/1008.html

 From the Ohio Department of Agriculture:  WEST NILE VIRUS
FOR IMMEDIATE RELEASE
August 8, 2002
REYNOLDSBURG - Recent lab test results confirmed the first case of West
Nile Virus in an Ohio horse stabled in Holmes County, the Ohio Department
of Agriculture said today. This is the first horse found to be infected
with the virus in Ohio.
The owner of the horse first noticed the animal had rear leg lameness on
July 19, according to state Agriculture Director Fred L. Dailey. After the
horse's condition deteriorated, the owner sought veterinary intervention.
The attending veterinarian, Paul Masters, D.V.M., of Orville, collected
blood samples and submitted them to the Ohio Department of Agriculture's
Animal Disease Diagnostic Laboratory, which forwarded them on July 29 to
the National Veterinary Services Laboratory in Ames, Iowa, for testing. The
horse, which had not been vaccinated, has been euthanized.
Although this was a clinical case in which the owner observed sickness in
the animal prompting a diagnostic blood test, the state agriculture
department routinely assists in the testing of horses and birds as part of
the state's efforts to monitor and prevent the spread of West Nile Virus.
Last July, a blue jay was the first positive indicator that West Nile virus
had officially arrived in Ohio.
Horses are "sentinels" of the disease rather than carriers; that is,
mosquitoes do not pick up the virus from infected horses. Horse owners
should watch for signs of infection by the virus in their animals and
should consult a veterinarian if those signs are present. For example,
infected horses might experience loss of appetite, fever, weakness,
paralysis of hind limbs, impaired vision, loss of coordination, aimless
wandering, convulsions, inability to swallow, circling, hyper-excitability,
or coma. The disease can be fatal in horses. Owners should consult with
their veterinarians to consider vaccinating horses against the virus.
Public health authorities continue disease and vector surveillance
activities, and the public should adopt effective safeguards against the
virus, including eliminating conditions in which mosquitoes can breed.
Horse owners should take other preventive steps to protect their animals
from mosquitoes, including:
Eliminating standing water on their property, to prevent mosquito breeding.
Housing horses inside at dawn, dusk, and night, which are peak mosquito
times.
Avoiding leaving lights on inside horse stables in the evening or overnight.
Placing incandescent bulbs away from the perimeter of stables.
Using fans to create air movement over stabled horses.
Removing all birds, including chickens, that are in or close to stables.
Using mosquito repellant on horses.
Fogging stables with pesticide in the evening.
Checking the property for dead blue jays and crows, and reporting them to
the local health department.
Primarily a wild-bird disease, WNV is a mosquito-borne virus, which
generally causes mild symptoms that mimic the flu in humans. In rare
instances, however, WNV can cause encephalitis (inflammation of the brain)
or meningitis (inflammation of the lining of the brain and spinal cord) in
humans. This happens in less than 1 percent of people bitten by an infected
mosquito. Those over age 50 and those with compromised immune systems are
most susceptible to the serious complications related to the virus.
Ohio Department of Health Director J. Nick Baird, M.D., is urging all
Ohioans to protect themselves and their loved ones from mosquito bites and
to remove standing water from their property.
"Because WNV is entrenched in Ohio, we all need to follow some simple steps
to help protect ourselves from mosquito bites," Baird said. "By following
this advice, we can minimize West Nile's impact on Ohio's health."
Personal Prevention Measures
Avoid outdoor activities between dusk and dawn when mosquitoes are likely
to be biting
If you must be outdoors when mosquitoes are active, cover up by wearing
shoes, socks, long pants and long-sleeves. Light colors are less attractive
to mosquitoes
Use mosquito repellent containing DEET according to label directions.
Adults should use repellent with no more than 30 percent DEET; for
children, 10 percent or less.
Eliminate Mosquito Breeding Sites
Remove all discarded tires from your property or put them under cover so
they don't collect water.
Dispose of tin cans, plastic containers, ceramic pots or similar
water-holding containers.
Make sure roof gutters drain properly, clean clogged gutters in the
spring and fall.
Clean and chlorinate swimming pools, outdoor saunas and hot tubs. If not
in use, keep empty and covered.
Drain water from pool covers.
Change the water in bird baths at least once a week.
Turn over plastic wading pools, and wheelbarrows, etc. when not in use.
Eliminate any standing water that collects on your property.
Remind or help neighbors to eliminate breeding sites on their properties.
Keep windows and doors closed and make sure screens are in good repair.
The state operates two toll-free telephone information lines to handle
questions from the public about West Nile virus. The Ohio Department of
Agriculture has a toll-free line for animal health questions, 800-300-9755,
staffed 8 a.m. to 5 p.m. weekdays by the department's Division of Animal
Industry staff. Questions regarding human health should be directed to the
Ohio Department of Health's toll-free line, 866-634-2968, staffed 8 a.m. to
4:30 p.m weekdays by state health department personnel.
The Ohio Department of Agriculture and Ohio Department of Health are
members of the Ohio West Nile Virus Workgroup. Other members are the Ohio
Department of Natural Resources, The Ohio State University, the Ohio
Environmental Protection Agency, Association of Ohio Health Commissioners,
Ohio Mosquito Control Association, Ohio Environmental Health Association,
and the U.S. Department of Agriculture.
-30-
Media contact for animal health issues: Mark Anthony, Ohio Department of
Agriculture, (614) 752-9817
Media contact for human health issues: Office of Public Affairs, Ohio
Department of Health, (614) 644-8562

Websites for more information:
Ohio Department of Health: "http://www.odh.state.oh.us/" (search for West Nile)
Ohio Department of Agriculture: "http://www.state.oh.us/agr/"
Centers for Disease Control and Prevention: "http://www.cdc.gov/" (search
for West Nile)
United States Geological Survey: "http://www.nwhc.usgs.gov/"
The Ohio State University College of Veterinary Medicine:
"http://prevmed.ohio-state.edu/"


David E Anderson, DVM, MS
The Ohio State University
         http://www.vet.ohio-state.edu/docs/ClinSci/bovine/index.htm
         http://www.vet.ohio-state.edu/docs/ClinSci/camelid/index.html
         http://www.internationalcamelidinstitute.org