West Nile Virus found in Dallas County
Mosquito control and vaccinations urged by officials

By LYNN MONTGOMERY | East Texas Edition

Horses should be protected against West Nile Virus, which has made its way to North Central Texas. Vaccine for horses is available and should be dministered, but one Texas Cooperative Extension agent strongly urges horse owners to first eliminate, or treat, standing water where mosquitos breed.

July 18, 2002 -- The West Nile Virus (WNV) is getting closer to East Texas and officials say it's just as important to deter mosquitoes as it is to vaccinate horses.

Two birds found in southwest Richardson and North Dallas tested positive for the virus, state and county health officials confirmed July 11.

Because the disease is transmitted by mosquitoes, which have fed on WNV-infected birds, a key component to help combat the disease is to control the mosquito population.

"I am taking a lot of calls from horse owners. My suggestion is to control the mosquito population," said Denton County Extension Agent Rebecca Parker.

There are ways to eliminate the mosquito larvae from tanks, according to Parker, such as organic products.

These products, according to literature, will not harm the fish in ponds nor livestock. Products like "mosquito dunks" and "mosquito bits" have Bacillus thuringiensis (Bt) as the active component.

Bt is a bacteria that only attacks insects, according to James Swart, Extension entolomogist.

The mosquito dunks range in price from $9 to $12 for a package of six and will provide coverage for about 30 days. According to the package, use one dunk per 100-square-foot area of water.

The mosquito bits is priced around $16 for a 36 ounce container. Usage, according to the directions, would be one teaspoon per 25-square-foot, one tablespoon per 75-square-foot or one-half pound per 2,178-square-foot.

The first application should last one to two weeks with the second application lasting three to four weeks, according to Bob Kirkpatrick at East Texas Landscaping and Fencing.

The mosquito baits are available at farm supply, feed and organic stores.

Kirkpatrick referred to "The Organic Manual," written by Howard Garrett, which makes the following suggestions for combating mosquitoes: encourage frogs, birds and bats; sprinkle instant coffee into stagnant water; garlic oil; gambusia and goldfish; garlic/pepper tea; citronella products; or cedar flakes (would need to be broadcasted on the surface of the soil).

Another suggestion to help your horses is to spray them with an insecticide.

"It is better to spray later in the afternoon or at night (which is when mosquitoes are most active)," Shepherd explained.

A suggestion by Dr. Bruce Lawhon, a Texas A&M Extension veterinarian, is to cut all tall grass that is not needed. One area for tall grass could be a ditch or drainage area.

"If horses are eating the grass, then that's fine. But, if they are not, cut it done. Tall grass is another breeding ground," Lawhon said.

Tires, or tire swings, are also breeding grounds for mosquitoes.

"I have three tires in my backyard and I put an old towel in the tires to absorb the water," Lawhon said.

Lawhon added that the people used to build fires when there was a mosquito problem and "horses are smart enough to stand in the smoke."

Horse owners will not be able to eliminate mosquitoes, according to Shepherd, but they can control them.

Horse owners also need to remember that the mosquito that bites their horse can also bite them. State health officials say people should wear protective clothing and insecticides after dusk.

Veterinarians and health officials are asking horse owners to vaccinate for the disease and watch for signs of head tremors or muscle twitches.

The West Nile vaccine's status is still under FDA's conditional license status.

"This vaccine is safe to use," said Dr. Dick Shepherd, a Denton County veterinarian. "I have probably vaccinated 500 horses. The side affects are virtually nonexistent except for maybe a mild temperature in which you would get with any vaccine."

Ft. Dodge is the only manufacturer for the WNV vaccine.

"The conditional licensed WNV vaccine is expected in August to receive full license by USDA," said Dr. Buddy Faries, Extension program leader for veterinary medicine. "Ft. Dodge has completed clinical trial efficacy that meets requirements for approval."

Efficacy is high and side effects are minimal. Most side effects are local injection site swellings, according to Faries.

If horse owners have not vaccinated, Shepherd recommends doing so as soon as possible. Faries also recommends vaccinating.

"The best time for annual boosters is late winter to early spring to have high immunity prior to emergence of mosquitoes," Faries stressed.

Horse owners will need to get the vaccine from their veterinarian and cost varies from $15 to $25 per dose.