More than 70 Texas horses have tested positive for West Nile virus (WNV) in 2012, according to statistics from the Texas Department of State Health Services.
On Oct. 15 the department reported through its website that 72 horses residing in 49 Texas counties had been confirmed positive since the beginning of the year. The majority of those counties are located in the eastern half of the state, with just a handful being confirmed in West Texas.
According to USDA Animal and Plant Health Inspection Service (APHIS) Animal Health Monitoring and Surveillance, Texas first reported equine WNV in 2002, when 1,699 horses contracted the disease. Case counts dropped drastically in 2003 and 2004, with 717 and 122 cases reported, respectively.
In 2005 just 27 Texas horses tested positive for the disease; however, the total rose to 111 in 2006 before dropping to 94 in 2007. From 2008 to 2010, less than 30 cases of WNV were confirmed annually, and the total plummeted to six in 2011.
Meanwhile, Texas' neighbor to the east, Louisiana, has also confirmed a high number of equine WNV cases this year; on Oct. 1, Laura Pursnell-Lindsay, public information director for the Louisiana Department of Agriculture and Forestry, told TheHorse.com that 60 WNV cases had been confirmed in that state so far this year.
Last week TheHorse.com also caught up with Maureen Long, DVM, MS, PhD, Dipl. ACVIM, professor in the University of Florida College of Veterinary Medicine Department of Infectious Diseases and Pathology. She explained that endemic mosquito-borne diseases tend to go through cycles, which is likely occurring this year.
"Endemic mosquito-borne diseases undergo cycles of 10-30 years, and I think this is an indication of normal cycle for WNV since it is now a resident disease," she relayed. "Many factors account for these cycles: the reservoir host becomes more susceptible again as adult resistant birds age and die, the virus changes or mutates and causes more disease, and cyclical weather patterns. One or all of these factors may be at play here. One prediction can be made, and it's that WNV is here to stay and we will see these cyclical outbreaks."
To combat this spike in cases, veterinarians nationwide are recommending horse owners take preventive measures to protect their animals from disease by:
- Vaccinating horses against WNV annually, and sometimes more frequently if the animals reside in a mosquito-dense area;
- Minimizing the mosquito population around horses by eliminating standing water sources, removing muck from areas near the animals, keeping horses stalled during peak mosquito hours (i.e., dawn and dusk), using equine-approved mosquito repellents and/or protective fly gear, and placing fans inside barns or stalls to maintain air movement;
- Discouraging wild birds from roosting near or in barns or stables.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.