Early WNV vaccination urged

Cattle Market & Farm Reports, Editorials
Mar 28, 2005
by WLJ
— Early case confirmed in California.
Veterinarians and government animal health officials are recommending earlier vaccinations for horses in an effort to prevent West Nile Virus (WNV) from becoming a severe problem this year.
“Horse owners should begin vaccinating their animals in March and April this year, which is earlier than usual, as an added precaution," said Wayne Cunningham, state veterinarian at the Colorado Department of Agriculture. "Depending on the levels of infection in an area, a second booster shot might be needed later this year, which is why it's important for them to consult with their local veterinarians."
WNV has caused more deaths in equine than any other vector-driven disease. This means that a vector, such as a mosquito, is needed to spread the disease, and horses cannot infect each other.
In addition to vaccinations, horse owners also need to reduce the mosquito populations and possible breeding areas. Recommendations include removing water sources, keeping animals inside during the bugs' feeding times, which are typically early in the morning and evening, and using mosquito repellents.
2005 case
California’s announcement earlier this month of the earliest confirmation of WNV ever recorded in a horse raises the potential for a widespread outbreak of the disease this year.
Livestock health officials in the state attributed the very early March case to the flooding that hit southern California during the months before and the mosquitoes that came along with that problem. Mosquitoes are considered a primary carrier of the virus and the primary vector that moves the disease from animal to animal.
Last year, 540 horses in the state were known to have contracted the disease, with 229 deaths. Of the known cases, 356 of the horses were not vaccinated and 145 more were vaccinated incompletely.
“Outbreaks of West Nile this year may be even worse than last year,” said California State Veterinarian Dr. Richard Breitmeyer. “Horse owners should contact their veterinarians as soon as possible to ensure vaccination status is current. If people get the necessary shots for their horses now, horses will have the protection they need against the deadly disease.”
Last year a total of 1,341 horses were confirmed infected with WNV, nationwide. That figure was way down from 5,181 in 2003 and 15,257 in 2002. However, federal and state livestock officials said the drop in cases last year doesn’t mean that the threat of the disease is any less than it was several years ago.
The disease can cause an inflammation of the brain and is transmitted by mosquitoes that can infect people and animals. Although both humans and animals have died from the disease, most WNV infections do not cause any illness.
Clinical symptoms seen in infected horses include an elevated temperature, stumbling, lack of coordination, weakness of the limbs or partial paralysis. Of the horses that exhibit clinical signs of the infection, one of three will most likely die from the infection. The symptoms of WNV are similar to Western Equine Encephalitis, which owners typically vaccinate their horses against.
Producers concerned that their horses may be infected with the disease later in the year are urged to contact their individual state department of agriculture and find out what days testing for the disease occurs.