Topical insecticide treatments to protect dogs from sand fly vectors of leishmaniasis.

Richard Reithinger,Ueslei Teodoro,Clive R Davies

doi:10.3201/eid0705.017516

Richard Reithinger, Ueslei Teodoro + Show 1 more

Open Access

https://doi.org/10.3201/eid0705.017516

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Abstract

We compared the susceptibility of sand fly vectors to four topical insecticide treatments applied to domestic dogs, a reservoir of human leishmaniasis. Dogs were exposed to sand flies pretreatment and at 1 week, 1 month, and 2 months posttreatment. Sand fly bloodfeeding and survival rate of both fed and unfed flies were significantly reduced by the permethrin, deltamethrin, and fenthion treatments, but diazinon had no effect. The survival rate of bloodfed sand flies was reduced by up to 86% with deltamethrin collars. The antifeeding effect suggests that deltamethrin collars may be recommended to dog owners to protect their pets from sandfly- borne diseases. The combined effects on sand fly feeding and survival indicate that epidemiologic, community-based trials are warranted to test whether deltamethrin collars could reduce the incidence of canine and, hence, human leishmaniasis.

Highlights

We compared the susceptibility of sand fly vectors to four topical insecticide treatments applied to domestic dogs, a reservoir of human leishmaniasis
The greatest antifeeding effect in all trials was detected on DM-treated dogs after 2 months, when bloodfeeding rates were reduced by 69% (95% confidence intervals [CI] 43,78)
The observed reduction in Lu. intermedia bloodfeeding and increase in sand fly deaths support the hypothesis that topical insecticides, including collars, could protect dogs against leishmaniasis

Summary

Introduction

We compared the susceptibility of sand fly vectors to four topical insecticide treatments applied to domestic dogs, a reservoir of human leishmaniasis. Sand fly bloodfeeding and survival rate of both fed and unfed flies were significantly reduced by the permethrin, deltamethrin, and fenthion treatments, but diazinon had no effect. The combined effects on sand fly feeding and survival indicate that epidemiologic, community-based trials are warranted to test whether deltamethrin collars could reduce the incidence of canine and, human leishmaniasis. In the past 20 years, the number of human leishmaniasis cases has dramatically increased, a trend that shows no signs of abating [3] Much of this increase may result from adaptation of Leishmania transmission cycles to the peridomestic environment as a response to deforestation and urbanization [4]. A high proportion of clinically cured dogs remain parasitologically positive and infectious to the sand fly vector [16]

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