West Nile Virus Update: Colorado State Veterinary Diagnostic Laboratory Witnessing a Large Increase of Wnv in Horses
The Colorado State University Veterinary Diagnostic Laboratory System, designated as the state of Colorado’s official diagnostic laboratory, reports a large increase in cases of West Nile virus in horses this year.
In total, as of Aug. 7, the lab’s serology technicians and virologist have tested 108 samples that were positive for WNV in equids. So far this year, one equine case tested positive in May, one case tested positive in June, 74 cases tested positive in July and 32 cases have tested positive so far in August. West Nile virus did not arrive in Colorado until August of last year and Colorado State’s Diagnostic Laboratory did not receive equine samples to test for the virus until September 2002.
"With the worst of mosquito season still to come, we are already seeing a large number of tests coming back positive for West Nile virus in horses," said Barbara Powers, director of Colorado State’s Veterinary Diagnostic Laboratory. "We are seeing many cases from central Colorado as well as a good amount from eastern Colorado. Horses in western Colorado, at this point, seem not to be infected with the virus."
Colorado State Veterinary Diagnostic Laboratory System offices in Fort Collins, Rocky Ford and Grand Junction test for WNV in horses. A breakdown of results from each lab follows.
– Main Colorado State University Veterinary Diagnostic Laboratory in Fort Collins:
– 148 samples received;
– 58 samples tested positive for WNV.
– Animal Disease Diagnostic Laboratory in Rocky Ford:
– 82 samples received;
– 50 samples tested positive for WNV.
– Western Slope Animal Diagnostic Laboratory in Grand Junction:
– 4 samples received;
– 0 samples tested positive for WNV.
The increased numbers in equine WNV cases coincide with increased numbers reported in humans and other animals by the Colorado Department of Public Health and Environment. According to the CDPHE, so far this year in Colorado:
– 154 humans have tested positive for WNV;
– 401 birds have tested positive for WNV;
– 78 chickens have tested positive for WNV;
– 154 equines have tested positive for WNV;
– 166 mosquitos have tested positive for WNV;
For more information, go on the Web to http://www.cdphe.state.co.us/dc/zoonosis/wnv.
To protect both horses and companion animals from WNV, Powers and other Colorado State veterinarians stress that owners should use methods of controlling mosquito populations on their property, such as eliminating standing pools of water where bugs can breed and keeping animals inside during the morning and evening when mosquitoes are most likely to be feeding.
A vaccine is available to help protect horses from contracting or dying from the disease. Colorado State University veterinarians are continuing to suggest to their clients that vaccinating equids according to the manufacturer’s recommendations is one important step toward preventing WNV disease in horses.
"We only know the vaccination history of about one-quarter of the samples we receive," said Hana Van Campen, section head of virology at the Diagnostic Laboratory. "However, only one horse that we know that had the full recommended dose of vaccine has contracted the disease. This horse has survived the infection."
A study previously released by Colorado State University summarized the background characterization of last year’s outbreak of West Nile virus in equids and suggested that vaccination is one very important step toward preventing the disease in horses. In the study, even horses that had not received both doses of vaccine several weeks prior to exposure to West Nile virus were more likely to survive than those that were non-vaccinated.
Horse owners should contact their veterinarian about vaccination recommendations. At this time, there are no WNV vaccinations for dogs, cats or other pets. Concerned owners should consult with their veterinarian if pets are exhibiting unusual symptoms.
Colorado State Veterinary Diagnostic Laboratory System offices in Fort Collins, Rocky Ford and Grand Junction can accept and test horse serum for WNV. The fee is $7 per serum sample or $5 each for two or more samples. Results generally are available within 48 hours, depending on volume.
Horse serology samples can be mailed or delivered in person during regular business hours to the closest Colorado State diagnostic laboratory listed below.
– Colorado State University Veterinary Diagnostic Laboratory
Veterinary Teaching Hospital
300 West Drake Road
Fort Collins, CO 80523
Phone: (970) 491-1281
Hours: 7:30 a.m.-5 p.m. Monday through Friday
– Western Slope Animal Diagnostic Laboratory
425 29 Road
Grand Junction, CO 81501
Phone: (970) 243-0673
Hours: 8 a.m.-noon and 1-5 p.m. Monday through Friday
– Animal Disease Diagnostic Laboratory
27847 Road 21
Rocky Ford, CO 81067
Phone: (719) 254-6382
Hours: 8 a.m.-noon and 1-5 p.m. Monday through Friday
For specific details about how to submit serology samples, go online to the Diagnostic Laboratory’s user guide at www.dlab.colostate.edu or call one of the labs directly at the phone numbers listed above.
Colorado State’s Veterinary Diagnostic Laboratory System, which offers a wide range of services in the areas of pathology, bacteriology, virology, immunology, toxicology, parasitology and endocrinology, provides timely, accurate and pertinent animal disease diagnostic services and educational outreach to veterinarians, animal industries and animal interests. These services include monitoring animal diseases such as WNV as they affect the domestic and wild animal populations.