The esperanza window trap reduces the human biting rate of Simulium ochraceum s.l. in formerly onchocerciasis endemic foci in Southern Mexico.

Mario A Rodríguez-Pérez,Eddie W Cupp,Javier A Garza-Hernández,Thomas R Unnasch,Mario C Salinas-Carmona,Olga Real-Najarro,Ildefonso Fernández-Salas,Filiberto Reyes-Villanueva,Brian L Weiss

doi:10.1371/journal.pntd.0005686

Abstract

BackgroundThe Esperanza Window Trap (EWT) baited with CO2 and human sweat compounds is attractive to Simulium ochraceum s.l., the primary vector of Onchocerca volvulus in the historically largest endemic foci in México and Guatemala.Methodology/Principal findingsThe ability of the EWT to locally reduce numbers of questing S. ochraceum s.l. was evaluated in two formerly onchocerciasis endemic communities in Southern México. At each community, two EWTs were placed in or near a school or household and flies were collected sequentially for a total of 10 days. Black fly collections were then carried out for an additional 10 days in the absence of the EWTs. Flies were also collected outside the dwellings to control for variations in the local fly populations. When the EWTs were present, there was a significant reduction in the human biting rate at both the household and school locations at collection sites, with a greater effect observed in the schools.Conclusions/SignificanceThese results indicate that the EWTs not only have potential as a black fly monitoring tool but may be used for reducing personal exposure to fly bites in Mesoamerica.

Highlights

The species belonging to the genus Simulium, commonly known as black flies, (Diptera: Simuliidae), serve as vectors of several pathogens including nematode parasites, protozoans and viruses [1]
We evaluated the ability of the Esperanza Window Trap (EWT) to reduce the personal biting rate by questing S. ochraceum s.l. in two formerly onchocerciasis endemic communities in Southern Mexico
When the EWTs were present, there was a significant reduction in the human biting rate at each of the four collection sites, varying from 14% to 51%

Summary

Introduction

The species belonging to the genus Simulium, commonly known as black flies, (Diptera: Simuliidae), serve as vectors of several pathogens including nematode parasites, protozoans and viruses [1]. Simulium ochraceum s.l. was the principal vector of the filarial parasite Onchocerca volvulus (the causative agent of river blindness or onchocerciasis) in Latin America and accounted for approximately 70% of the transmission in this region [2]. The Onchocerciasis Elimination Program for the Americas (OEPA), has eliminated onchocerciasis throughout in four of the six endemic countries of Latin America, employing a strategy primarily based upon twice per year community wide mass treatments with Mectizan (ivermectin) [6]. African national and international programs are attempting to replicate this success in Africa, again relying primarily on community-wide treatment of the endemic populations with Mectizan [7]. The Esperanza Window Trap (EWT) baited with CO2 and human sweat compounds is attractive to Simulium ochraceum s.l., the primary vector of Onchocerca volvulus in the historically largest endemic foci in Mexico and Guatemala

Methods

Results

Discussion

Conclusion