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Evaluation of parasite infectivity for Lutzomyia longipalpis by xenodiagnosis in dogs treated for natural visceral leishmaniasis

ABSTRACT:

The outcome of a multidrug chemotherapeutic protocol against canine visceral leishmaniasis (VL) has been evaluated for its effect on dogs’ capacity of transferring Leishmania infantum to sand flies by xenodiagnosis. Thirty-five naturally infected dogs were examined before and during treatment with a combination of metronidazole, ketoconazole, and allopurinol, at every three months up to one year. For each evaluation, treated dogs were individually submitted to xenodiagnosis and quantitative PCR to quantify parasite load in sand flies. The treatment was effective in blocking parasite transmission from host to sand flies (p=0.011) in the assessed dogs. There was a significant correlation between clinical improvement and sand fly infectivity: dogs that achieved better clinical conditions showed a lower chance of L. infantum transference to vector by xenodiagnosis (r=0.528, p=0.002). These results demonstrate that the treatment of dogs with the proposed protocol may represent an alternative to dog culling in Brazil for disease control, since these drugs are not used for treating human VL in endemic areas.

INDEX TERMS:
Parasite infectivity; Lutzomyia longipalpis; xenodiagnoses; dogs; visceral leishmaniasis; Leishmania infantum; multidrug chemotherapy; quantitative PCR

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