A POLYMERASE CHAIN REACTION-BASED ASSAY FOR DETECTION OF WUCHERERIA-BANCROFTI IN HUMAN BLOOD AND CULEX-PIPIENS

Human blood samples and indoor-resting Cullex pipiens were collected i n 33 randomly selected houses from different sectors of a village in t he Nile Delta of Egypt which was endemic for Wuchereria bancrofti. Blo od was also collected from subjects with no history of living in filar ial endemic areas. Human blood samples were divided and assessed by bo th membrane filtration and polymerase chain reaction (PCR). Similarly, mosquito samples were assessed by both dissection and PCR. Blood pool s representing each household were tested by PCR. If a pool gave a pos itive result, then individual blood specimens were also rested by PCR. Of the 33 houses tested, both membrane filtration and blood pools ass ayed by PCR identified 14 (42.4%) 'infected houses'. PCR detected para site deoxyribonucleic acid (DNA) in blood pools from an additional 3 h ouseholds that gave negative results by membrane filtration. Of 178 en demic blood samples tested by membrane filtration, 22 (12.3%) had micr ofilariae and all were individually positive by PCR. Although microfil aria counts were lower in blood collected during the day than in night -collected blood, the PCR results were consistent, regardless of time of collection. All non-endemic blood samples were negative by PCR. Amo ng the 33 houses tested, mosquito pools assayed by PCR identified 17 ( 51.5%) as 'infected households'. Of these, 8 houses (47%) contained at least one microfilaraemic resident. One 'infected household' was iden tified by mosquito dissection. We concluded that PCR is a powerful epi demiological tool for screening villages for the prevalence of W. banc rofti. PCR detection of W. bancrofti DNA in blood-fed mosquitoes could be used initially to locate endemic areas with transmission of bancro ftian filariasis. PCR detection of W. bancrofti DNA in blood collected during the day could then be used to assess W. bancrofti infection ra tes.