Chagas disease control: deltamethrin-treated collars reduce Triatoma infestans feeding success on dogs

Dogs are domestic reservoir hosts of Trypanosoma cruzi, the aetiological agent of Chagas disease. Using an experimental set-up mimicking rural mud-and-thatch houses, we evaluated the effect of deltamethrin-treated dog collars on the feeding success and survival of Triatoma infestans, the main T. cruzi vector in Latin America. Seven collared and three uncollared control dogs were exposed to colonized T. infestans at day 0 (i.e. before attachment of collars), at 15 days, and then monthly for 3 months post collar attachment. Following overnight exposure to uncollared dogs, 96% (1473/1538) of bugs fed, of which 51% (746/1473) fully engorged. Feeding rates were significantly reduced on collared dogs for up to 1 month post collar attachment with the lowest rates of 91% (551/604) observed at day 30 (P < 0.05). Amongst those bugs that fed, engorgement rates were significantly reduced on collared dogs throughout the trial, during which average rates were 31% (543/1768) (P < 0.001). No collar effect on individual bug survival was observed. Although observed effects on feeding and engorgement were limited, the strong association between blood-feeding, blood meal size and T. cruzi transmission suggests that deltamethrin-treated dog collars could help to control canine (and possibly human) T. cruzi infection.