Sumario: |
Background: Insecticide thermal fogging (ITF) is a tool to control vector borne diseases. Insecticide application
success for vector control has been associated with housing materials and architecture. Vector abundance is
correlated with weather changes. Nevertheless, housing quality and weather impacts on vector abundance have
been unaccounted for in most New World insecticide control trials for leishmaniasis vectors.
Methods: We conducted a 15 month insecticide control trial that included two deltamethrin [6 mg a.i.m-2] based
ITF interventions in 12 of 24 monitored houses at Trinidad de Las Minas, a hyperendemic cutaneous leishmaniasis
transmission village in western Panamá. During the study we followed sand fly (SF) abundance, keeping track of
rainfall and quantified housing quality using an index based on architecture and construction materials.
Results: We found a 50 to 80% reduction in SF density in the fogged houses when compared with control houses,
while controlling for seasonal changes in SF abundance associated with rainfall. We found heterogeneities in the
reductions, as abundance changed according to SF species: Lutzomyia gomezi, Lu. panamensis, Lu. dysponeta and
Lu. triramula reduced in density between 40% and 90% after ITF. In contrast, Lu. trapidoi density increased 5% after
ITF. Differences in the impact of ITF were associated with housing quality, the most destitute houses, i.e., those with
features that ease insect entrance, had a disproportionally larger SF abundance, in some cases with increased
domiciliary SF density following the ITF.
Conclusion: Our results suggest the potential of insecticide application to control SF density and leishmaniasis
transmission could depend on housing quality beyond insecticide efficiency
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