Application of a polymerase chain reaction-ELISA to detect Wuchereria bancrofti in pools of wild-caught Anopheles punctulatus in a filariasis controlarea in Papua New Guinea

Chemotherapy-based eradication programs are aimed at stopping transmission of Wuchereria bancrofti by its obligatory mosquito vector. This study compa res one year post-treatment W. bancrofti infection rates of Anopheles punct ulatus, the main vector of lymphatic filariasis in Papua New Guinea, using traditional dissection techniques and a polymerase chain reaction (PCR)-bas ed ELISA of a parasite-specific Ssp I repeat. A total of 633 mosquitoes in 35 batches were dissected. Six batches contained W. bancrofti-infected mosq uitoes, giving a minimum infection rate of 0.9%. This value was not differe nt than the actual infection rate, which was 9 (1.4%) of 633 mosquitoes (P = 0.48). The DNA was extracted from 47 pools containing a mean of 13.2 mosq uitoes per pool. A total of 621 mosquitoes were processed for the PCR-ELISA , including 486 caught by human bait and 135 by light trap, which included both dead and live mosquitoes. Of 23 pools of alcohol-preserved human-bait mosquitoes, seven were positive by the PCR-ELISA, giving an infection rate identical to that obtained by dissection of individual mosquitoes (1.4%). T he minimum infection rates for pools of Light-trap mosquitoes found dead an d alive were 2.7% (2 of 74) and 4.9% (3 of 61), respectively. These values did not differ from each other (P = 0.84), but the overall infection rate o f light-trap mosquitoes was greater than that of mosquitoes captured by hum an bait (3.7% versus 1.4%; P = 0.09). These data indicate that the PCR-ELIS A of a W. bancrofti Ssp I repeat using pools of mosquitoes is comparable to traditional dissection techniques for monitoring transmission intensity fo llowing introduction of mass chemotherapy. This approach may also be useful for rapid and cost-effective assessment of transmission in endemic areas w here the frequency of overt lymphatic pathology is low.