ABSTRACT
El municipio Sifontes del estado Bolívar es la principal área endémica a malaria de Venezuela. Durante los cinco años anteriores al estudio se reportaron allí un promedio anual de 14 mil casos, alcanzándose en 2009 la cifra de 19.408, constituyendo una situación de epidemia. En la búsqueda de estrategias alternativas al uso de insecticidas, se evaluó la eficiencia para el control de malaria de una formulación comercial de Bacillus sphaericus Neide (VectoLex® CG 7,5%). Entre mayo 2010 y mayo de 2011 se aplicó biolarvicida con motomochila (Solo®) a dosis de 20-30 kg/ha a frecuencia mensual en todos los criaderos de Anopheles darlingi, An. marajoara y An. nuneztovari ubicados alrededor de las viviendas de cuatro comunidades de la parroquia San Isidro de este municipio, acompañadas de colectas de anofelinos adultos con atrayente humano y trampa de luz CDC y ultravioleta. Después de 48 semanas de aplicación, la reducción de 80% de la malaria en el área, más la reducción de la densidad de larvas en los criaderos, muestran que el biolarvicida es eficiente para controlar malaria. Los resultados también sugieren que la prevalencia de larvas es un buen indicador en un programa de control de vectores basado en la aplicación de biolarvicida, no así la de adultos, cuya abundancia no se corresponde con la de larvas. Es la primera vez que se evalúa la eficiencia de B. sphaericus para controlar malaria en Venezuela, considerándose estos resultados prometedores, si el tratamiento de criaderos con biolarvicida es selectivo y se hace a la cobertura, frecuencia y dosis correctas, e integrado a otras estrategias de control de vectores.
The Sifontes municipality in Bolivar state is the principal malaria-endemic region in Venezuela. During the five years prior to the study an annual average of 14,000 cases was reported reaching an epidemic level of 19,408 cases in 2009. As part of the search for vector control measures that could be used as alternatives to insecticides, a commercial formulation of Bacillus sphaericus Neide (VectoLex® CG 7.5%) was evaluated. Between May 2010 and May 2011 monthly dosages of 20-30 kg/ha of Vectolex were sprayed using a motorized backpack (Solo®) in larval Anopheles darlingi, An. marajoara and An. nuneztovari habitats close to houses in four communities in the parish of San Isidro, Sifontes municipality. In parallel, adult anophelines were captured using human baits, CDC light traps and ultraviolet light traps. After 48 weeks of application there was an 80% reduction in malaria as well as a decrease in larval density demonstrating the effectiveness of B. sphaericus for the control of this disease. Moreover, the results suggest that larval prevalence is good indicator for biolarvicide based malaria control programs whereas the abundance of adults, which does not correlate with larval abundance, is not. This is the first time that the effectiveness of B. sphaericus for malaria control has been evaluated in Venezuela. These results show that spraying larval habitats for malaria control can be effective when integrated with other vector control strategies if the treatment is selective and carried out at the correct frequency and dosage in order to ensure adequate coverage of the larval habitat.
ABSTRACT
Anopheles darlingi Root is the major vector of human malaria in the Neotropics and has been considered to be the sole malaria vector in French Guiana. The presence of other potential vectors suggests that malaria may be transmitted by other species under certain conditions. From 2006-2011, all anopheline specimens collected from 11 localities were assayed to determine if the Plasmodium circumsporozoite protein was present. In addition to An. darlingi, we found Anopheles oswaldoi, Anopheles intermedius and Anopheles nuneztovari specimens that were infected with Plasmodium sp. Further investigations on the behaviour and ecology of An. oswaldoi, An. intermedius and An. nuneztovari are necessary to determine their role in malaria transmission in French Guiana.