First detection of dengue and chikungunya viruses in natural populations of Aedes aegypti in Martinique during the 2013 - 2015 concomitant outbreak / Primera detección del virus del dengue y del chikungunya en poblaciones naturales de aedes aegypti en martinica durante el brote concomitante del 2013 al 2015

ABSTRACT Dengue and chikungunya viruses are transmitted by Aedes mosquitoes. In Martinique, an island of the French West Indies, Aedes aegypti is the suspected vector of both arboviruses; there is no Aedes albopictus on the island. During the concomitant outbreak of 2013 - 2015, the authors collected wild A. aegypti populations, and for the first time, detected dengue and chikungunya viruses in field-collected females. This paper demonstrates the mosquito's role in transmission of both dengue and chikungunya on the island, and also highlights a tool that public health authorities can use for preventing outbreaks.(AU)

RESUMEN Los virus del dengue y del chikungunya se transmiten a través de los mosquitos del género Aedes. Se da por supuesto que en Martinica, en las Antillas francesas, Aedes aegypti es el vector de ambos arbovirus, puesto que en la isla no hay Aedes albopictus. Durante el brote concomitante del 2013 al 2015, los autores recogieron muestras de poblaciones salvajes de A. aegypti y, por primera vez, detectaron virus del dengue y del chikungunya en las hembras obtenidas en el terreno. En el presente artículo se demuestra que el mosquito actúa en la isla como transmisor tanto del dengue como del chikungunya y se describe, además, una herramienta que las autoridades de salud pública pueden utilizar para prevenir los brotes.(AU)

Efficacy of bifenthrin-impregnated bednets against Anopheles funestus and pyrethroid-resistant Anopheles gambiae in North Cameroon

Background: Recent field studies indicated that insecticide-treated bednets (ITNs) maintain their efficacy despite a high frequency of the knock-down resistance (kdr) gene in Anopheles gambiae populations. It was essential to evaluate ITNs efficacy in areas with metabolic-based resistance. Methods: Bifenthrin was used in this experiment because it is considered a promising candidate for bednets impregnation. Nets were treated at 50 mg/m2; a dose that has high insecticidal activity on kdr mosquitoes and at 5 mg/m2; a dose that kills 95of susceptible mosquitoes under laboratory conditions with 3 minutes exposure. Bednets were holed to mimic physical damage. The trial was conducted in three experimental huts from Pitoa; North-Cameroon where Anopheles gambiae displays metabolic resistance and cohabits with An. funestus. Results: Bifenthrin at 50 mg/m2 significantly reduced anophelines' entry rate (80). This was not observed at 5 mg/m2. Both treatments increased exophily in An. gambiae; and to a lesser extent in An. funestus. With bifenthrin at high dosage; over 60reduction in blood feeding and 75-90mortality rates were observed in both vectors. Despite presence of holes; only a single An. gambiae and two An. funestus females were collected inside the treated net; and all were found dead. The same trends were observed with low dosage bifenthrin though in most cases; no significant difference was found with the untreated control net. Conclusion: Bifenthrin-impregnated bednets at 50 mg/m2 were efficient in the reduction of human-vector contact in Pitoa. Considerable personal protection was gained against An. funestus and metabolic pyrethroid resistant An. gambiae populations