Seroprevalence of West Nile virus in feral horses on Sheldon National Wildlife Refuge, Nevada, United States.
Abstract: We screened 1,397 feral horses (Equus caballus) on Sheldon National Wildlife Refuge, Nevada, United States, for IgM and IgG against flavivirus during 2004-2006, 2008, and 2009. Positive serum samples were tested for neutralizing antibodies to West Nile virus (WNV) and St. Louis encephalitis virus (SLEV). One animal was positive for antibody against WNV in 2004, but all others tested in 2004-2006 were negative. In 2008 and 2009, we found evidence of increasing seropositive horses with age, whereas seroprevalence of WNV decreased from 19% in 2008 to 7.2% in 2009. No horses were positive for antibody against SLEV. Being unvaccinated, feral horses can be useful for WNV surveillance.
Publication Date: 2011-04-05 PubMed ID: 21460023PubMed Central: PMC3062462DOI: 10.4269/ajtmh.2011.10-0467Google Scholar: Lookup
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- Journal Article
Summary
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The researchers carried out a study testing the presence of West Nile virus in horses living on Sheldon National Wildlife Refuge in Nevada. A pattern of increasing presence of the virus with the age of the horses was noticed, however the overall presence decreased from the year 2008 to 2009.
Study Arrangements and Participant Selection
- The experiment was carried out on 1,397 feral horses, also known as Equus caballus, that resided on Sheldon National Wildlife Refuge in Nevada, United States.
- The testing was conducted over the course of multiple years: 2004 to 2006, and later in 2008 and 2009.
Testing Methodology
- Researchers looked for the presence of IgM and IgG, two classes of immunoglobulins or antibodies, against flavivirus. Flavivirus is a genus of viruses that includes the West Nile virus (WNV).
- Positive samples, where these antibodies were detected, underwent further tests to identify neutralizing antibodies specific to WNV, as well as St. Louis encephalitis virus (SLEV).
Study Findings
- In the preliminary testing phase between 2004 and 2006, only one animal tested positive for WNV. However, all the other horses tested during this period were free of the virus.
- In the following testing phase of 2008 and 2009, a trend of increasing seropositive horses with age was noticed. Seropositive refers to the presence of antibodies in the blood serum against a particular antigen, in this case, WNV.
- Between the years of 2008 and 2009, there was a notable decrease in the seroprevalence of WNV in the tested horses. The rate of prevalence dropped from 19% in 2008 to 7.2% in 2009.
- No horses were found to be carrying antibodies against the SLEV during the entire period of testing.
Conclusion and Implications
- Since the horses were feral and therefore unvaccinated, they serve as a good reference point for observing the circulation of WNV in the natural environment. Their presence or absence of the disease can potentially be used for surveillance of the virus’ prevalence in the wildlife area.
Cite This Article
APA
Franson JC, Hofmeister EK, Collins GH, Dusek RJ.
(2011).
Seroprevalence of West Nile virus in feral horses on Sheldon National Wildlife Refuge, Nevada, United States.
Am J Trop Med Hyg, 84(4), 637-640.
https://doi.org/10.4269/ajtmh.2011.10-0467 Publication
Researcher Affiliations
- U.S. Geological Survey, National Wildlife Health Center, 6006 Schroeder Road, Madison, WI 53711, USA. jfranson@usgs.gov
MeSH Terms
- Aging
- Animals
- Antibodies, Viral / blood
- Horse Diseases / epidemiology
- Horse Diseases / immunology
- Horses
- Immunoglobulin G / blood
- Immunoglobulin M / blood
- Nevada / epidemiology
- Seroepidemiologic Studies
- Time Factors
- West Nile Fever / epidemiology
- West Nile Fever / immunology
- West Nile Fever / veterinary
- West Nile virus / immunology
References
This article includes 12 references
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Citations
This article has been cited 2 times.- Barba M, Fairbanks EL, Daly JM. Equine viral encephalitis: prevalence, impact, and management strategies.. Vet Med (Auckl) 2019;10:99-110.
- Garnier R, Graham AL. Insights from parasite-specific serological tools in eco-immunology.. Integr Comp Biol 2014 Sep;54(3):363-76.
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