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 number s of tandem repeat (VNTR) sequences are employed to prime amplificatio n of human DNA in the polymerase chain reaction (PCR) and the radiolab elled products are analysed by high resolution denaturing gel electrop horesis. Matching of DNA profiles allows identification of the individ ual human host. Bloodmeals of 1-5 female Anopheles gambiae Giles mosqu itoes, caught dead or alive in verandah-trap huts wherein two people h ad slept overnight protected by intact insecticide-impregnated bednets , were analysed: thirty-five out of thirty-nine profiles generated wer e identical to those of the sleepers under the nets. Thus the blood-fe d mosquitoes found after impregnated nets have been used cannot, in mo st cases, be explained away by entry of already fed mosquitoes into th e huts.