East Texas

By COSHANDRA DILLARD
Staff Writer

Although cases of the West Nile virus in Texas have consistently dropped over the past several years, local health officials say East Texans should not be complacent about taking steps to prevent contracting the disease. Mosquitoes that carry the virus are most prevalent July through September, and as dry weather conditions blanket the region, there are greater chances for infecting mosquitoes to breed.

However, Dr. James Wright, regional zoonosis veterinarian at the Department of State Health Services, said he could not accurately predict if the impending dry heat will result in a surge of West Nile cases. But, he added, it won't hurt to take the necessary precautions.

"There is no way to anticipate it, but why take a chance when it's so easy to prevent it?" he said.

Dry, warm weather is a safe haven for mosquitoes because they need shallow, stagnant water to survive, health officials said. Rain and the wave action in large pools of water kill larvae because breeding grounds are disturbed.

Mosquitoes can breed in small cups, rock holes, buckets and bird baths. Officials recommend replacing water in a bird bath at least once a week and emptying containers that are not in use. For large containers that cannot be conveniently drained or washed out, there are mosquito dunks -- donut-shaped pesticides that kill mosquito larvae -- available at retail stores, Wright said.

Each year, local health authorities spray a larvaecide throughout Tyler to keep mosquitoes at bay. Tyler's mosquito control program has been under way since late March and could continue until late October, or when the temperature drops below 60 degrees, said Shawn Markmann, director of Tyler Mosquito Control.

Although the spraying ensures there are no swarms of mosquitoes in public areas and near natural water sources, it is not the most effective thing to do, Markmann said.

"The most effective thing that can be done is source reduction; showing people where mosquitoes are breeding," he said. "For years, we've been killing mosquitoes. We treat those as best as we can, but it's the container breeding that we can't always see."

The health district typically receives the most complaints about mosquito swarms in July and August, particularly during dry conditions.

Last year, they received 198 complaints of mosquito nuisances, and 97 percent of the complaints were the result of a man-made breeding site, or standing water in the yard or container. However, Markmann said, there has been a 50 percent decline in complaints since 2004, the height of the West Nile disease surge.

West Nile disease can be very mild, but in rare cases, it can lead to serious complications including encephalitis, an infection of the brain.

In the U.S., there were 1,356 human cases of West Nile disease and 44 deaths in 2008. So far this year, there have been six human cases, one of which was in Texas. There have been no reported deaths.

West Nile disease cannot be spread by human-to human-contact, and not everyone that gets bitten by a mosquito contracts the virus, as there are many different species of the insect.

In addition, about 80 percent of people who contract the virus never show any symptoms, Markmann said.

Wright also noted that West Nile cases may have taken a dive in recent years because the introduction into the community may have given residents "herd" immunity -- meaning a high percentage of the population is immune to the virus, which virtually stops the spread of the disease because there are no new hosts to infect.

There is no vaccine for humans, but one is available for horses, Wright said. He said withmild cases, the virus just runs its course, but in severe cases, a patient may be hospitalized and given "supportive treatment."

Residents concerned about mosquitoes at their homes can call Tyler Mosquito Control, at 903-535-0045.