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

Abstract

Abstract. Chemotherapy-based eradication programs are aimed at stopping transmission of Wuchereria bancrofti by its obligatory mosquito vector. This study compares one year post-treatment W. bancrofti infection rates of Anopheles punctulatus, the main vector of lymphatic filariasis in Papua New Guinea, using traditional dissection techniques and a polymerase chain reaction (PCR)-based ELISA of a parasite-specific Ssp I repeat. A total of 633 mosquitoes in 35 batches were dissected. Six batches contained W. bancrofti-infected mosquitoes, giving a minimum infection rate of 0.9%. This value was not different than the actual infection rate, which was 9 (1.4%) of 633 mosquitoes (P ϭ 0.48). The DNA was extracted from 47 pools containing a mean of 13.2 mosquitoes 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%). The minimum infection rates for pools of light-trap mosquitoes found dead and alive were 2.7% (2 of 74) and 4.9% (3 of 61), respectively. These values did not differ from each other (P ϭ 0.84), but the overall infection rate of lighttrap mosquitoes was greater than that of mosquitoes captured by human bait (3.7% versus 1.4%; P ϭ 0.09). These data indicate that the PCR-ELISA of a W. bancrofti Ssp I repeat using pools of mosquitoes is comparable to traditional dissection techniques for monitoring transmission intensity following introduction of mass chemotherapy. This approach may also be useful for rapid and cost-effective assessment of transmission in endemic areas where the frequency of overt lymphatic pathology is low.

Comparison of Methods for Xenomonitoring in Vectors of Lymphatic Filariasis in Northeastern Tanzania

“…In a comparison of infection rates between Anopheles punctulatus collected using light traps and human landing catches in Papua New Guinea, it was proposed that infection rates were higher in light trap catches because of the increased proportion of bloodfed mosquitoes in light trap catches. 6 This presents an important question for xenomonitoring in general: how representative is a PCR-positive mosquito of W. bancrofti prevalence in a FIGURE 3. Wuchereria bancrofti infection levels using quantitative polymerase chain reaction (qPCR) in pooled Culex quinquefasciatus DNA extracts collected from light (blue) and gravid (red) traps in Vyeru, Tanga Region of northeastern Tanzania.…”

“…4 Second, mosquitoes can be collected and tested (xenomonitoring), either through dissection to find the filarial larvae, or through the use of molecular methods to detect the DNA of the filarial worms. 5 Light traps are commonly used for the collection of mosquitoes for LF xenomonitoring, [6][7][8] and are usually placed indoors near a sleeping person who is protected with an untreated mosquito net. Other methods such as human landing catches have been used, 9 but this method is used less often due to ethical concerns.…”

Survey of Bancroftian filariasis infection in humans and Culex mosquitoes in the western Brazilian Amazon region: implications for transmission and control

“…The PCR has proven to be a powerful tool to evaluate the contamination intensity of the mosquitoes in endemic areas and, because of these advantages, has replaced the conventional dissection methods for the diagnosis of W. bancrofti in mosquitoes 15 . This method, in addition to being more sensitive than dissection, enables a large number of samples to be processed in a short period.…”

Mass Treatment to Eliminate Filariasis in Papua New Guinea

“…The mosquito species was determined, and insects were examined for infective (third-stage) larvae. 18,19 The biting rate (the number of mosquitoes attempting to take a blood meal per person), the infective biting rate (the number of Anopheles punctulatus that had at least one infective larva), and the transmission potential were determined. 20,21 …”