Evaluation of the Impact of DEC Treatment on Vector Infection in the Program of Lymphatic Filariasis Control in Recife, Brazil

摘要

Bancroftian filariasis is focally endemic in Recife, a city located on the Northeastern coast of Brazil. Culex quinquefasciatus is the vector responsible for transmission. Although most of the bancroftian filariasis endemic areas in Brazil in the last century are currently considered extinct, Recife still remains as a transmission area, with more than 40.000 infected people. The World Health Organization (WHO) has launched a global program for the elimination of lymphatic filariasis (LF) until 2020 and many country-level elimination strategies are being achieved worldwide. On November 2003, a single course DEC mass treatment was administered to 17.000 individuals from Agua Fria, a district of Recife, where microfilarial (mf) prevalence reached 6,21%. Adult Cx. quinquefasciatus females from houses in that area were collected before and during treatment, in order to monitor vector infection rate and to detect the expected decreasing of microfilaraemia due to the mass drug administration (MDA). A total of 6,409 females mosquitoes were examined. Using PCR we observed a reduction in the vector infection rate from 0.96 % (before treatment) to 0.20 % after the first MDA and 0.0% five months after the second MDA treatment. Thenceforward all the samples collected showed to be negative. These results point out that the control program of filariasis is being effective.