Colorado enhances surveillance of equine vector-borne diseases
Continued partnership between the Colorado State University Veterinary Diagnostic Laboratories with the Colorado Department of Agriculture and the Colorado Department of Public Health and Environment aims to enhance surveillance for all three diseases and understand their prevalence in Colorado.
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The Colorado State University Veterinary Diagnostic Laboratories are continuing their partnership with the Colorado Department of Agriculture (CDA) and the Colorado Department of Public Health and Environment (CDPHE) for enhanced vector-borne disease surveillance for equids and camelids in 2026, focusing on western equine encephalitis Virus (WEEV), eastern equine encephalitis virus (EEEV), and West Nile virus (WNV).
The partnership aims to enhance surveillance for all three diseases and understand their prevalence in Colorado. Western equine encephalitis virus is present in the U.S. but has not yet been detected in Colorado, while eastern equine encephalitis virus has not been detected in the U.S. since the late 1990s. West Nile Virus has been widespread in the U.S. since 1999.
In 2025, CDA, CDPHE, and CSU partnered to perform surveillance and tested samples from 15 horses, two alpacas, and one donkey across seven different Colorado counties. All tested specimens were negative for WEEV and EEEV.
Testing for all three diseases is available to Colorado equine and camelid owners through the CSU Veterinary Diagnostic Laboratories. Owners should submit samples to the Fort Collins location. Free testing is available for a limited number of submissions and pathogens. To maximize the program’s effectiveness, the lab encourages submission of samples from unvaccinated animals (for WEEV/EEEV/WNV).
How to submit a sample to test for WEEV, EEEV, or WNV
Submission instructions:
- Fill out the equine neuro reportable disease form (for equines) or the reportable disease case report form (for camelids).
- Contact Christina Weller with the CSU Fort Collins Veterinary Diagnostic Laboratory for any questions on testing criteria at [email protected]. Submit a CSU VDL general submission form and write: “EEE/WEE/WNV PCR testing for CDPHE surveillance program” in the history section at the bottom of the front page of the form. Mail or drop off samples to the CSU Fort Collins Veterinary Diagnostic Laboratory.
- If rabies is a concern, please use a rabies testing request form.
Specimens requested:
- Antemortem
- Cerebrospinal fluid (CSF) preferred;
- Whole blood (EDTA-PTT) accepted;
- If possible please also submit serum to be banked for possible future antibody screening (if you are submitting serum for WNV IgM ELISA, these specimens may be banked for future EEE/WEE surveillance testing)
- Postmortem
- Brain and/or CSF
As a reminder, neurological disease is a reportable condition in equids in Colorado. The CDA requests veterinarians submit an equine neuro reportable disease form for all cases which meet this criterion or are suspect for WNV, WEEV, or EEEV. For neurologic camelids suspicious for WNV or other reportable conditions, veterinarians can complete the generic reportable disease case report form.
CDA and CDPHE will coordinate with the reporting veterinarian for any positive results. Positive findings through this initiative will not trigger regulatory action or herd-level interventions beyond potential recommendations for management in consultation with the submitting veterinarian.