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Keywords

Vector-borne disease; Xenomonitoring; Gravid Traps; Aedes polynesiensis; Culex quinquefasciatus; Lymphatic Filariasis

Abstract

Lymphatic filariasis (LF) is a mosquito-borne disease caused by Wuchereria bancrofti, which is endemic in American Samoa. The effort to eliminate LF has been highly successful, and is now in the monitoring phase to ensure continued progress. One of the monitoring methods is molecular xenomonitoring (MX) using PCR to detect W. bancrofti DNA in mosquitoes. Currently MX uses BG Sentinel traps to collect the LF vector Aedes polynesiensis. But the BG Sentinel traps catch relatively few Ae. polynesiensis, and most of those captured have not yet fed on blood. Gravid traps target mosquitoes that have already fed on blood, and have been used to collect large numbers of Culex quinquefasciatus for MX where that species is a vector. Though Cx. quinquefasciatus is not an LF vector in American Samoa, parasite DNA can be detected in non-vectors as well as vectors. We hypothesize that gravid traps targeting Cx. quinquefasciatus is more efficient for MX than the BG Sentinel trap targeting Ae. polynesiensis.

For our study, we compared two alternative gravid traps to the BG Sentinel trap. Two of each trap type were set in each of two villages and rotated daily in a Latin square design. The daily average catch rate for Ae. polynesiensis and Cx. quinquefasciatus were compared to assess the relative efficacy of the traps. If one or both gravid traps prove to be effective in capturing large numbers of Cx. quinquefasciatus, then they may provide a more efficient alternative to the BG Sentinel for LF MX in American Samoa.