Effectiveness of Systemic Insecticide Dog Treatment for the Control of Chagas Disease in the Tropics.

Simple Summary: Chagas disease, a vector-borne disease caused by the parasite Trypanosoma cruzi, is a significant threat to human and canine health in the tropics. To control the transmission of T. cruzi, systemic insecticide treatment of dogs with fluralaner has been proposed as an intervention for canine and potentially human Chagas disease. In this study, we evaluated the efficacy of canine treatment regimens with fluralaner to reduce Chagas disease infections (once every three months and once every twelve months) in high and low endemic regions using a data-driven mathematical model. Our study shows that Fluralaner treatment can effectively reduce T. cruzi transmission in humans, but may increase infections in dogs if canine consumption of triatomine increases. The effectiveness of the treatment regimen was shown to vary substantially with the underlying intensity of T. cruzi transmission and the increased rate of canine consumption of dead triatomines. Our study provides new evidence to support further empirical studies on the potential impact of mass treatment of dogs with systemic insecticides as a novel and additional intervention for the control and elimination of Chagas disease in the tropics. Chagas disease, caused by Trypanosoma cruzi and transmitted by triatomines, can lead to severe cardiac issues and mortality in many mammals. Recent studies have shown that systemic insecticide treatment of dogs is highly effective in killing triatomines. Here, we assessed the impact of dog treatment on T. cruzi transmission. We developed a mathematical model of T. cruzi transmission among triatomines, dogs, humans, and rodents. We used the model to evaluate the impact of dog treatment regimens on T. cruzi transmission dynamics to determine their effectiveness in reducing T. cruzi infection among hosts. We show that a 3-month treatment regimen may reduce T. cruzi incidence among humans by 59–80% in a high transmission setting, and 26–82% in a low transmission setting. An annual treatment may reduce incidence among humans by 49–74% in a high transmission setting, and by 11–76% in a low transmission setting. However, dog treatment may substantially increase T. cruzi prevalence among dogs if dog consumption of dead triatomines increases. Our model indicates that dog treatment may reduce T. cruzi infections among humans, but it may increase infections in dogs. Therefore, a holistic approach targeting different hosts is necessary for Chagas elimination. [ABSTRACT FROM AUTHOR]