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| Vol. 22, No. 15 |
| August 15, 2000 |
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Texas Department Of Health Adds West Nile Virus to Monitoring Efforts Add a new name to the list of diseases mosquitoes potentially can carry to humans - West Nile infection. The West Nile virus, closely related to both St. Louis Encephalitis (SLE) and dengue viruses, was first seen in the United States last year. Although the outbreak affected people in the New York City area, the virus could spread to other areas of the country. The Texas Department of Health (TDH) is expanding its mosquito monitoring system to detect if West Nile virus is introduced to the state, says Julie Rawlings of TDH's Infectious Disease Epidemiology and Surveillance Division. To most people, mosquitoes are just an annoying pest with an irritating bite. But these insects can carry serious, sometimes deadly organisms that cause diseases such as SLE and West Nile infections along with both Western and Eastern Equine Encephalitis and dengue fever. A large dengue outbreak occurred last year in Texas, with 62 cases reported, including one death. Wild birds are the principal reservoirs of mosquito-borne encephalitis viruses. Mosquitoes feed on infected birds, then transmit the virus to humans and animals. To detect West Nile virus, TDH will concentrate on monitoring mosquito species likely to feed on birds migrating from the northeastern United States through the Gulf Coast. Areas involved in the expanded monitoring system include Chambers, Galveston, Brazoria, Nueces, Kleberg, Kenedy, Cameron and Hidalgo counties. Harris County will have its own monitoring system. In addition, testing for West Nile virus will be included in the long-established programs in Brazos, Dallas, El Paso, Jefferson, Orange, Lubbock and Wichita counties. Also, city and county health departments, public health regions, military installations, universities and other local mosquito control programs send specimens to the TDH Lab for identification, Rawlings says. Mild infections of mosquito-borne encephalitis may occur with only a headache. More severe infections may include headache, high fever, neck stiffness, disorientation, coma and tremors. With West Nile infections, flu-like symptoms include fever, headache, sore throat, body aches, fatigue often with skin rash and swollen lymph glands. Dengue fever is characterized by fever, headache, joint pain, muscle aches and rash. About 82 varieties of the ever-present mosquito are found in Texas. However, only about a dozen transmit serious diseases, says Paul Fournier, supervisor of the TDH Bureau of Laboratories Parasitology-Entomology Branch. The common house mosquito (Culex quinquefasciatus), Asian tiger mosquito (Aedes albopictus) and Aedes aegypti are the most common around Texas that carry disease. These backyard biters are drawn to areas with a ready water supply to reproduce. "It only takes a thimble of water for these insects to breed," Fournier says. "It takes about one week for a mosquito to go from egg to adult. Longevity of an adult female is about 30 days." The primary way people can cut down on the multiplying families of mosquitoes, according to Fournier, is to eliminate breeding sites. People are encouraged to:
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