Filariasis elimination in Egypt: impact of low microfilaraemics as sources of infection for mosquitoes

The elimination strategy for lymphatic filariasis aims at reducing blood microfilaraemia to levels at which vector transmission cannot be sustained. We aimed to determine whether patients with pre-treatment low or ultra-low microfilaria [MF] counts could be a reservoir of infection after mass drug administration [MDA] with a combined regimen. Laboratory-reared mosquitoes were fed on 30 volunteers after 2 rounds of MDA. Microfilaria uptake, infectivity rates and number of Wuchereria bancrofti L3 per mosquito were assessed. One year after MDA-1, 6 subjects transmitted MF, but up to 9 months after MDA-2 transmission failed. Six months after MDA-2 > 90% had clear MF smears and either failed to transmit MF or transmitted MF that did not develop to L3. We conclude that the transmission cycle is seriously weakened after MDA-2

Field evaluation of a rapid-format kit for the diagnosis of bancroftian filariasis in Egypt

The AMRAD-ICT Filariasis Test [ICT-Fil] is a new, rapid-format card test for the detection of bancroftian antigenaemia in human blood. We evaluated the performance of the test under field conditions in Egypt by comparing 1813 endemic and 102 nonendemic participants. Endemic participants were tested for microfilaraemia [thick smear and membrane filtration] and serum antigenaemia [ELISA]. The infection rates detected were 2.8% by thick smear, 3.5% by membrane filtration, 8.8% by ELISA and 9.0% by ICT-Fil. The card test detected antigenaemia in 98.0% and 95.3% of microfilaraemia carriers testing positive by thick smear and blood filtration respectively. Nonendemic participants were ICT-Fil negative. Identical results were obtained for 173 out of 184 [94%] endemic participants tested by the serum and whole blood ICT-Fil versions