Aedes aegypti surveillance and correlation with the occurrence of dengue fever in Bahia, Brazil

RESUMO

Due to the high frequency of dengue fever cases and the presumed association of such an epidemic with an increase in the population of the mosquito vector, Aedes aegypti, we examined the records of the Ministry of Health in the state of Bahia, Brazil, regarding the monitoring of domestic mosquito larvae in municipalities throughout the state. The "House Index" number for larvae in domestic water reservoirs was determined for each municipality based on annual surveys from 1990 to 1994, and in 1996. In 1996, 69 percent of the municipalities surveyed in Bahia were positive, and 30 percent had indices above 5 percent. During 1990 and 1991, the level of larvae identified was low and stable; however, during November and December, 1992, a dramatic increase was recorded. The increase continued until 1996, when over 100-fold increases in house indices were recorded in Feira de Santana and Ilhéus, and 60-fold in Salvador. The dengue fever epidemic was documented in the region beginning in 1994. A strong correlation has been demonstrated between an increase in the mosquito larvae population and the emergence of dengue fever.