Aedes Aegypti - Spread of Disease and Prevention

Spread of Disease and Prevention

Aedes aegypti is a vector for transmitting several tropical fevers. Only the female bites for blood which she needs to mature her eggs. Understanding how the mosquito detects its host is a crucial step in the spread of the disease. Aedes aegypti are attracted to chemical compounds that are emitted by mammals. These compounds include ammonia, carbon dioxide, lactic acid, and octenol. Scientists at the Agricultural Research Service have studied the specific chemical structure of octenol in order to better understand why this chemical attracts the mosquito to its host. They found that the mosquito has a preference for "right-handed" (dextrorotatory) octenol molecules.

The CDC traveler's page on preventing dengue fever suggests using mosquito repellents that contain DEET (N, N-diethylmetatoluamide, 20% to 30% concentration, but not more). It also suggests the following:

1. Mosquitoes in general usually bite at dusk and dawn but may bite at any time during the day – especially indoors, in shady areas, or when the weather is cloudy. In particular, Aedes aegypti bites essentially during daytime.
2. The mosquito's preferred breeding areas are in areas of stagnant water, such as flower vases, uncovered barrels, buckets, and discarded tires, but the most dangerous areas are wet shower floors and toilet tanks, as they allow the mosquitos to breed in the residence. Research has shown that certain chemicals emanating from bacteria in water containers stimulate the female mosquitoes to lay their eggs. They are particularly motivated to lay eggs in water containers that have the correct amounts of specific fatty acids associated with bacteria involved in the degradation of leaves and other organic matter in water. The chemicals associated with the microbial stew are far more stimulating to discerning female mosquitoes than plain or filtered water in which the bacteria once lived.
3. Wear long-sleeved clothing and long trousers when outdoors during the day and evening.
4. Spray permethrin or DEET repellents on clothing, as mosquitos may bite through thin clothing.
5. Use mosquito netting over the bed if the bedroom is not air conditioned or screened. For additional protection, treat the mosquito netting with the insecticide permethrin.
6. Spray permethrin or a similar insecticide in the bedroom before retiring.

Although the lifespan of an adult Aedes aegypti is two to four weeks depending on conditions, Aedes aegypti's eggs can be viable for over a year in a dry state, which allows the mosquito to re-emerge after a cold winter or dry spell.