West Nile Virus prevention gearing up

By MONETTE TAYLOR | South Central Texas Edition

While many horse owners are concentrating on foaling season, it's also time to be thinking about vacciations against West Nile Virus and other equine encephalities, according to Dr. James Tiemann. Wet conditions are setting up a prime mosquito season. -Staff photo by

March 6, 2003 -- After sliding on ice just a week or so ago, it's hard to imagine that we are rapidly slipping into mosquito season.

With the winter moisture and expected spring rains, South Central Texas residents, and horse owners, can look forward to a large crop of mosquitoes, and with mosquitoes comes the threat of the West Nile virus.

"I would suspect that it (West Nile) may be worse this year considering the fact that we're set up for a mosquito crop ... I mean, if you've got a wet summer and a wet spring and you have a tremendous crop of mosquitoes, you're going to have an awful big flare up, I would think," explained Dr. James Tiemann, DVM, in Fayette County.

According to an article in the February edition of the Texas Veterinarian, the "West Nile virus has been confirmed in every county in Texas or in an adjacent county." Also, the U.S. Department of Agriculture has declared the virus an epidemic throughout the entire United States.

Dr. James Tiemann

"There were two positive cases (of West Nile) that were confirmed (in Fayette County), but there were probably more cases than that that weren't really confirmed," said Tiemann.

For the entire state in 2002, West Nile Virus was detected in over 175 of Texas' 254 counties and over 1,300 equines were infected with the virus, according to Texas Animal Health Commission statistics. As it swept through Texas last year, a total of 2,137 cases of West Nile were reported in not only equines, but humans, and even dogs and cattle.

West Nile was a big topic of consideration at a veterinary medicine conference Tiemann attended in Florida. One presenter, a leading authority, reported on 40 or 50 cases of West Nile that were treated. "They got some of them (infected horses) to survive, some were permanently damaged and some reversed to back the way they were. They discussed what you should vaccinate, and when you shouldn't vaccinate," the veterinarian recalled.

He came away from the seminar with the recommendation for horse owners that "in areas where you have a lot of mosquitoes ... originally, you give two doses of vaccine. The first one, followed by another three weeks later. But, they are recommending that you do biannual vaccinations in mosquito endemic areas, and we're in a mosquito endemic (restricted to a particular) area."

After the second vaccination is given, it is now recommended that equine owners give booster shots every six months, "at least, for the foreseeable future.

"It's not going to go away. Even the vaccine is not 100 percent effective," said Tiemann. "You're playing Russian roulette if you don't (vaccinate), because it may be worse this year, and it may not be as bad. It's hard to say."

The veterinarian pointed out horse owners should vaccinate against West Nile, but also for Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis (WEE).

"Eastern and Western encephalitis mirrors the mosquito population," he added.

Producers should watch their animals for disposition changes, unusual behavior and trouble standing or getting up to a standing position. Tiemann said there are a number of things that cause similar behavior, but a veterinarian should be contacted for a proper diagnosis.

Concerning other animal health diseases, Tiemann, briefly, discussed Foot and Mouth Disease (FMD).

"I think you kind of have to watch out for (FMD). I think the biggest problem is ... if it's going to come into this country ... it's probably going to be carried in by some tourist, not by the livestock importation business. If not tourists, terrorists," he said.

If the United States should have a FMD outbreak, such as Great Britain experienced, it could cause the same havoc, he explained. Just another reason for producers to keep a watchful eye on their livestock, he concluded.