Control trial of Lutzomyia longipalpis s.l. in the Island of Margarita, Venezuela

Abstract

The incidence of the American visceral leishmaniasis (AVL) in the Island of Margarita, a major tourist centre in Venezuela, has been increasing between 1998 and 2001. Lutzomyia longipalpis s.l. is the recognized vector, which was found naturally infected with Leishmania spp, indistinguishable from the parasites recovered from dogs and children. In 1999-2000, we conducted a control trial in Santa Ana del Valle and Las Cabreras, which have similar epidemiological and ecological conditions. The trial was based on intradomestic residual spraying of lambda-cyhalothrin, E.C., 25 mg/m2 and spatial fogging of fenitrothion around the houses at 30 g/ha. Sandfly abundance was recorded using Centers for Disease Control (CDC) traps indoors and outdoors. We found significantly reduced sandfly populations in the target locality. Wall bioassays showed that the residual effect of the insecticide lasts for about 3 months. We believe that indoor spraying with lambda-cyhalothrin three times a year, at a dose slightly greater than 25 mg/m2, might reduce the L. longipalpis s.l. population to a level low enough for achieving a significant reduction of the indoor transmission, thus protecting small children from the disease.

Control of Visceral Leishmaniasis in Latin America—A Systematic Review

“…A significant decrease of sandfly abundance was observed, with a residual effect of indoor spraying of 3 months. Main limitation of this study was the specific construction style of the houses: completely cemented, plastered and oil-painted walls and zinc roofs, which lowers its external validity [106].…”

Ecology of the Leishmania Species in the Guianan Ecoregion Complex

“…Vector-culling programs have already been tried in some Amazonian foci but results have been heterogeneous. 187,[217][218][219][220] As reported by Lainson and others, 173 the variety of leishmanial parasites observed in the Amazonian mammalian fauna compels us to believe that the predominantly sylvatic ecology of different Leishmania species was present in the GEC before European colonization and the relentless impact it had on the virgin rain forests. However, the primitive source of the parasite is still likely to be present in the degraded forests.…”

Lutzomyia longipalpis behavior and control at an urban visceral leishmaniasis focus in Argentina

“…Therefore, the recommendation about focus interventions by insecticides need further validation in this southern focus, with risk focused outside the house during the first half of the night, with improved active principles, formulations, ways of applications, and strategies that take into account also the environmental and reservoir risk factors 1,3,17 . In this context, FELICIANGELI et al 14 after a controlled trial, proposed lambda-cyalothrin indoor spraying three times per year, with a dose higher than usual. However, even if the outdoor associated risk is not taken into account, this strategy could only be applied at microfocal level and not in city-wide programs, further when the indiscriminate use of insecticides could induce resistance both in target and not targeted species 1 , and pyrethroids have been used broadly in Aedes control.…”

“…Although some studies reported deltamethrin residual effects up to 9-12 months inside houses 13,19 , strong anti-feeding effects when applied to dogs as collars or topically, and repellent effects in impregnated bednets 7,8,9 , and pyrethroids as lambdacyalothrin reducing impact on Lu. longipalpis sand fly captures after focal or indoor applications 14,18 , there are many reports about the short or transient effects of fenitrothion 14 , cypermethrin 12 and deltamethrin as peridomestic sprayed insecticide 1,13,22,36 . Unfortunately the effects of insecticides for longer periods than 14 days could not be assessed in this study due to an abrupt change in the weather conditions that reduced the population; both in the intervention and the control group, but the results obtained were consistent with the literature.…”