A new methodology for sampling blackflies for the entomological surveillance of onchocerciasis in Brazil

Abstract

The effectiveness of the MosqTent® trap was evaluated in endemic area to onchocerciasis in Brazil. This study seeks to provide subsidies for the monitoring of the onchocerciasis transmission in the country. The study was carried out at the Homoxi and Thirei villages, located in the Yanomami Indigenous Land, in the state of Roraima. This area presents hyperendemicity, high blackflies densities, large population migrations and mining activities. The Homoxi and Thirei villages are assisted by the Brazilian Ministry of Health. To conduct the present study, the village leader, health leaders and the Brazilian Ethics Committee were consulted. Blackflies captures were carried out simultaneously at the Homoxi and Thirei, using systematized methods to allow for comparisons between the traditional Human Landing Catch (HLC) and HLC protected by the MosqTent®. The female blackflies were captured at two equidistant capture stations per locality, by two collectors per station, for five consecutive days. Individuals captured by interval/station/day were counted, identified and maintained at -20°C. The underlying probability distributions and the differences between the methods for the independent sample data were verified in a comparative statistical analysis between the use of the MosqTent® and the HLC. A total of 10,855 antropophilic blackflies were captured by both methodologies. A total of 7,367 (67.87%) blackflies belonging to seven species were captured by MosqTent® —Simulium incrustatum s.l (99.06%); S. guianense s.l (0.74%), S. oyapockense s.l (0.01%), S. exiguum (0.10%), S. metallicum (0.05%), S. ochraceum (0.03%) and S. minusculum s.l (0.01%). Moreover, 3,488 (32.14%) blackflies belonging to four species were captured by HLC—S. incrustatum s.l (98.33%); S. guianense s.l (1.38%), S. oyapockense s.l (0.26%) and S. metallicum (0.03%). The MosqTent® was more effective and efficient when compared to HLC. When comparing total blackflies captured/day, the MosqTent® was more efficient than HLC (p = 0.031) with a means of 799.4 blackflies/day versus 217.6 blackflies/day by HLC. The results demonstrated improved performance and high reliability of the MosqTent® compared to the traditional HLC method.

An entomological study of onchocerciasis vectors, Simulium damnosum s.l., in Kinshasa, Democratic Republic of Congo

“…This difference may have resulted from an increased y activity when people were concentrated around the breeding sites, namely in the morning and at sunset, as in our case. Our results corroborate with those of Nascimento-Carvalho in Brazil or Homoxi, where the biting activity of female Simuliidae showed a bimodal pattern, with peaks in activities early morning (between 7 and 8.50 a.m.) and afternoon (between 4 and 5.50 p.m.) [39]. In Thirei, the biting activity was evenly distributed throughout the day [40].…”

“…In Thirei, the biting activity was evenly distributed throughout the day [40]. Black ies were captured simultaneously in Homoxi and Thirei using systematic methods to compare the traditional capture method using human bait (Human Landing Catch, HLC) with HLC protected by MosqTent® [39]. Comparing the anthropophilic pro les of black ies captured using MosqTent® and HLC, the percentage of species caught uctuated seasonally in both Homoxi and Thirei, except between 11 h-11 h 50 min in Homoxi and between 4 and 4.50 p.m. in Thirei, where the difference was based on the method of capture [39].…”

The Search for an Efficient Black Fly Trap for Xenomonitoring of Onchocerciasis

“…In the face of global elimination efforts and targets, there is an urgent need to develop vector traps which can effectively replace HLCs in disease monitoring and surveillance. Several traps have been tested for their potential to capture host seeking black fly species for disease monitoring [ 10 – 14 , 19 – 21 , 23 , 24 ]; however the most promising of such traps in recent times is the EWTs. These traps have clearly demonstrated promise in their ability to replace HLCs and may provide an added advantage as a means to control black fly populations if they are deployed in large numbers in endemic communities.…”

“…The first challenge encountered is that some authors report difficulties in the availability of the insect adhesives [ 21 ] used to trap the black flies in EWTs. Also the challenge with the cost of these adhesives even when they are available and the difficulties with application have been discussed [ 24 ]. A solution to this challenge may be to develop local alternatives using locally available materials so that the problem with cost and availability of the commercially manufactured adhesives can be eliminated.…”

Frequência E Perfil De Sensibilidade Antimicrobiana De Bacilos Entéricos Isolados Da Cavidade Bucal De Pacientes Hiv Soropositivos

“…Quando dobrada, suas dimensões se tornam compactas, medindo 0,50m x 0,50m [ LIMA et al, 2017). No caso da operação da armadilha por dois técnicos-coletores, o segundo deverá ficar na câmara externa, obedecendo a mesma opção de captura do técnico-coletor localizado na câmara interna (NASCIMENTO-CARVALHO et al, 2017). Os simulídeos também entram na armadilha através de espaços na parte inferior da câmara externa, que fica levantada a aproximadamente 30cm do chão (Fig.…”