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close this bookEmergency Vector Control after Natural Disaster (PAHO)
close this folderPart II: Control measures for specific vectors
close this folderChapter 5: Aedes aegypti
View the document(introductory text...)
View the documentSurveillance
View the documentControl of Aedes aegypti
View the documentEvaluation of Control Measures

(introductory text...)

Aedes aegypti is the vector of dengue, dengue hemorrhagic fever and urban yellow fever. It is a domestic mosquito that breeds in artificial containers in and around human dwellings. As containers proliferate, the species achieves high levels of density. This mosquito has also been known to breed in artificial containers placed some distance from human dwellings, and in natural containers, such as tree holes, bamboo, coconut shells and large snail shells. Any given area has slightly unique breeding habits, due to differences in the habitats and lifestyles of humans. In areas where water is stored or collected, open containers furnish ideal habitats. Such breeding sites should be given extra attention after a natural disaster, especially if the normal water supply is disrupted. Cisterns, cans, bottles, cemetery urns, tires and almost any discarded container that holds fresh water may also become infested.

The adult female mosquito deposits its eggs singly on the side of the container at, or immediately above, the waterline. Rains associated with some disasters provide the needed water to allow hatching, because the eggs are able to withstand drying for several months. Excessively heavy rains quite often wash away much of the initial egg deposition. However, large numbers of Aedes aegypti are quickly produced in numerous new oviposition sites. When conditions are favorable, hatching can occur within two or three days after ovipositioning.

Larval development, under favorable conditions, can be completed in five to seven days. The fourth instar larva molts to a pupal stage, and transformation to an adult is completed during the two to three day pupal period. Consequently, the life cycle can be completed in about ten or more days.

The emerging adults usually do not disperse more than a hundred meters and the females will readily enter nearby houses or any other man-made dwelling. In order to develop eggs, females require a blood meal for which humans are the preferred host. Biting usually occurs during, but is not limited to, daylight hours. In many cases humans are not aware of being bitten. The adult may live for six to eight weeks and, once infected with the viruses of yellow fever or dengue, remains so for life.