Fluralaner systemic treatment of chickens results in mortality in Triatoma gerstaeckeri, vector of the agent of Chagas disease

Background: Chagas disease remains a persistent vector-borne neglected tropical disease throughout the Americas and threatens both human and animal health. Diverse control methods have been used to target triatomine vector populations, with household insecticides being the most common. As an alternative to environmental sprays, host-targeted systemic insecticides (or endectocides) allow for application of chemicals to vertebrate host resulting in toxic bloodmeals for arthropods (xenointoxification). Methods In this study, three systemic insecticide products were evaluated for their ability to kill triatomines by treating chickens orally and allowing triatomines to feed on treated birds. The products included: Safe-Guard® Aquasol (fenbendazole), Ivomec® Pour-On (ivermectin), and Bravecto® (fluralaner). Triatoma gerstaeckeri nymphs were allowed to feed on live birds at 0, 3, 7, 14, 28, and 56 days post-treatment. Triatoma gerstaeckeri survival and feeding status were recorded and analyzed using Kaplan-Meier curve and logistic regression. Results Fluralaner caused up to 100% mortality in T. gerstaeckeri through 14 days post treatment but not after; in contrast, all insects which fed on fenbendazole and ivermectin-treated birds survived. Liquid chromatography tandem mass spectrometry (LC-QQQ) analysis was used to detect the concentration of fluralaner and fenbendazole in chicken plasma. Fluralaner was detected at 3-, 7- and 14-days post treatment but not later, while fenbendazole concentration was below the limit of detection at all time points. Conclusions Xenointoxification using fluralaner in poultry is a potential new tool for integrated vector control to reduce risk of Chagas disease.