FROM THE PRESIDENT

For many Texas Gulf Coast residents, mosquitoes are an annoyance, having ruined many a summer outdoor activity. From time to time, however, mosquitoes are more than mere pests, and instead pose a significant public health threat. Take now, for example, when daily news reports confirm West Nile virus infections in mosquitoes, birds, and other animals in our area.

Mosquito season in Houston runs from May to October, and during this peak time, it’s imperative that we take measures to protect against West Nile virus, which can cause a form of encephalitis (brain inflammation) similar to St. Louis encephalitis, which is more commonly known and also carried by mosquitoes.

Most people who are infected with West Nile virus show no or only mild symptoms such as low-grade fever and headache, body aches, and occasionally skin rash and swollen lymph glands. More severe signs and symptoms can include high fever, stiff neck, muscle weakness, disorientation, encephalitis, coma and rarely, death. People over age 50 have the highest risk of developing a severe illness, because as bodies age, they have a harder time fighting off disease. People with compromised immune systems are also at increased risk, however, anyone can get the virus.

While West Nile virus can infect a host of animals, including humans, it always is traced back to birds. Mosquitoes take the rap, because after feeding on infected birds, they transmit the virus on to people and other animals when feeding again. But remember, the virus originated in birds – mosquitoes are just the carriers, or "vectors."

Although much attention has focused on blue jays as the virus’s main target, the American crow actually is more susceptible, and therefore provides a barometer to detect viral activity.

West Nile virus is not spread from person to person, nor can people get the virus by handling infected animals. People can only become infected with the virus after being bitten by an infected mosquito. Symptoms usually appear three to 15 days after a mosquito bite. No specific treatment is available, however, several groups are working on developing a vaccine.

City, county and state agencies have joined forces to fight the West Nile virus. Activities are aimed at minimizing human illness through public education; early diagnosis and vector control; tracking the virus as its geographic range expands; identifying locations where disease poses the greatest threat; and identifying key vector species that contribute to the disease’s transmission.

Active surveillance, trapping, ground and aerial spraying are under way, and will continue until the threat subsides. To date, West Nile virus has been confirmed in Culex mosquitoes collected at six sites in Houston.

To help prevent mosquito-borne diseases, the Houston Department of Health and Human Services recommends keeping screens on windows and doors in good condition, and using mosquito repellant containing 35 percent DEET for adults and less than 10 percent for children. Concentrations higher than 35 percent provide no additional protection.

While West Nile virus has been commonly documented in Africa, Eastern Europe, Western Asia, and the Middle East, it was not identified in the Western Hemisphere until 1999, when it was found in New York. The continued expansion of the virus indicates its permanent establishment in the Western Hemisphere, making precautionary measures all the more crucial.

E-Mail: tmcinfo@texmedctr.tmc.edu
URL: http://www.tmc.edu/tmcnews/07_15_02/page_14.html