Peer-reviewed veterinary case report
West Nile virus outbreak in Texas horses in 2002 and survival rates
By Ward, Michael P et al.·Published in Veterinary microbiology·2006·Department of Veterinary Integrative Biosciences, United States·View original on PubMed →
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Original publication title: Characteristics of an outbreak of West Nile virus encephalomyelitis in a previously uninfected population of horses.
- Species:
- horse
Plain-English summary
A large outbreak of West Nile virus (WNV) encephalomyelitis affected horses in Texas, with symptoms like unsteady walking, muscle twitching, and severe depression. Between June and December 2002, nearly 1,700 cases were reported, and many of the affected horses had not been vaccinated in the past year. Sadly, about one-third of the horses did not survive, with those showing severe symptoms like falling down having the worst chances. Vaccination can significantly lower the risk of death, even if given shortly before exposure to the virus.
People also search for: West Nile virus in horses · horse vaccination for West Nile virus · symptoms of West Nile virus in horses
Abstract
Equine West Nile virus (WNV) encephalomyelitis cases - based on clinical signs and ELISA serology test results - reported to Texas disease control authorities during 2002 were analyzed to provide insights into the epidemiology of the disease within a previously disease-free population. The epidemic occurred between June 27 and December 17 (peaking in early October) and 1,698 cases were reported. Three distinct epidemic phases were identified, occurring mostly in southeast, northwest and then central Texas. Significant (P<0.05) disease clusters were identified in northwest and northern Texas. Most (91.1%) cases had no recent travel history, and most (68.9%) cases had not been vaccinated within the previous 12 months. One-third of cases did not survive, 71.2% of which were euthanatized. The most commonly reported presenting signs included ataxia (69%), abnormal gait (52%), muscle fasciculations (49%), depression (32%) and recumbency (28%). Vaccination status, ataxia, falling down, recumbency and lip droop best explained the risk of not surviving WNV disease. Results suggest that the peak risk period for encephalomyelitis caused by WNV may vary substantially among regions within Texas. Recumbent horses have a poor prognosis for survival. Vaccines, even if not administered sufficiently in advance of WNV infection within a district, may reduce the risk of death by at least 44%.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/16971067/