Analysis of mosquito bloodmeals by DNA profiling

Human specific genetic markers have been used to profile the human DNA found within a mosquito bloodmeal. In this technique, variable numbers of tandem repeat (VNTR) sequences are employed to prime amplification of human DNA in the polymerase chain reaction (PCR) and the radiolabelled products are analysed by high resolution denaturing gel electrophoresis. Matching of DNA profiles allows identification of the individual human host. Bloodmeals of 125 female Anopheles gambiae Giles mosquitoes, caught dead or alive in verandah-trap huts wherein two people had slept overnight protected by intact insecticide-impregnated bednets, were analysed: thirty-five out of thirty-nine profiles generated were identical to those of the sleepers under the nets. Thus the blood-fed mosquitoes found after impregnated nets have been used cannot, in most cases, be explained away by entry of already fed mosquitoes into the huts.