Mosquito-Borne Illness Risk in Southeast Texas

West Nile virus is the mosquito-borne disease most consistently reported in Harris and Montgomery County. It is transmitted primarily by Culex mosquitoes, which breed in standing water and tend to feed at dusk and dawn. Most people infected with West Nile never have noticeable symptoms. About 20 percent develop a fever, headache, body aches, joint pain, or a rash. Less than one percent develop serious neurological illness.

The risk is not zero, but it is also not evenly distributed. Older adults and people with compromised immune systems are at higher risk for severe disease. The peak transmission window in this area is July through September, when Culex populations peak and migrating birds (the primary wildlife reservoir) are still concentrated.

The yellow fever mosquito (Aedes aegypti) and the Asian tiger mosquito (Aedes albopictus) are both present in the Kingwood area. Both are capable of transmitting dengue fever, Zika, and chikungunya. These diseases are not native to Texas, but local transmission does occur in some years, particularly in areas close to the Mexican border. In the Houston area, the risk is primarily from travelers returning from endemic regions who are then bitten by local Aedes mosquitoes.

Aedes mosquitoes behave differently from Culex. They bite during the day, are aggressive biters, and breed in very small amounts of water, including the inside of a bottle cap, a clogged gutter, a bird bath that has not been changed, or a bucket in the yard. That makes them harder to avoid and easier to breed inadvertently.

Heartworm is a serious, potentially fatal disease in dogs and cats transmitted by mosquitoes. The parasite uses mosquitoes as an intermediate host and is common throughout the Houston area. Unlike human mosquito-borne illnesses, heartworm risk is present essentially year-round in Southeast Texas because the climate does not get cold enough to reliably kill off the mosquito populations that transmit it.

The American Heartworm Society recommends year-round heartworm prevention for all dogs and cats in the Gulf Coast region. This is one area where the warm climate keeps baseline risk higher than most of the country.

The most effective thing you can do on your own is eliminate standing water. Mosquitoes need only about half an inch of water and a week to complete their larval stage. Common sources include: flower pot saucers, clogged gutters, low spots in the lawn, unused tires, children's toys, bird baths, and tarps with pooled water.

Drill holes in the bottom of garbage cans and recycling bins stored outside. Change bird bath water at least twice a week. Treat ornamental ponds with Bacillus thuringiensis israelensis (Bti) dunks, a naturally occurring bacterium safe for fish and wildlife that kills mosquito larvae.

Barrier treatments to the vegetation on your property are the next layer. Mosquitoes rest in shaded, humid foliage during the day. Treating those resting areas keeps the population knocked down between breeding cycles.

EPA-registered repellents containing DEET, picaridin, IR3535, or oil of lemon eucalyptus are the most effective personal protection options. The CDC recommends DEET concentrations of 20 percent or higher for protection lasting several hours. Wearing long sleeves and pants during peak biting times (dusk and dawn for Culex, all day for Aedes) reduces exposure considerably.