Insecticidal efficacy of fluralaner (Bravecto®) against Triatoma brasiliensis, a major vector of Trypanosoma cruzi in Brazil

ABSTRACT

Background: Triatomines are responsible for the vector transmission of the protozoan parasite Trypanosoma cruzi, which causes Chagas disease. Triatoma brasiliensis is the main vector of the parasite in Brazil, and dogs are an important reservoir of the parasite. The aim of this study was to evaluate the insecticidal effect of fluralaner (Bravecto) on T. brasiliensis after a blood meal in treated dogs. Methods: Healthy mongrel dogs (n = 8) were recruited from the Zoonoses Control Center (ZCC) in the city of Natal, Rio Grande do Norte, Brazil, and randomized into two groups, a fluralaner (Bravecto)-treated group (n = 4) and a control group (n = 4). Colony-reared third-, fourth- and fifth-instar nymphs of T. brasiliensis nymphs (n = 10) were allowed to feed on dogs from both groups for 30-40 min, once monthly, for up to 12 months. Bug mortality was observed up to 5 days after each blood meal. Results: Mortality in triatomines which had a blood meal on fluralaner (Bravecto)-treated dogs was 100 per cent for up to 7 months after treatment, with mortality decreasing to 66.4 per cent after 8 months, 57 per cent after 9 months, 35 per cent after 10 months, 10 per cent after 11 months and 0 per cent after 12 months. The mortality of triatomines that fed on non-treated control dogs was always less than or equal 2.5 per cent. Conclusions: Our results suggest that fluralaner (Bravecto) treatment of dogs induces long-term mortality of T. brasiliensis after the blood meal. This is a potential approach to be used to control vector transmission of T. cruzi, the etiological agent of Chagas disease, especially in endemic areas.