A Scoping Review of Mathematical Models Used to Investigate the Role of Dogs in Chagas Disease Transmission

SIMPLE SUMMARY: Chagas disease- caused by the parasite Trypanosoma cruzi and vectored by triatomine insects (‘kissing bugs’)- poses a serious threat to human and dog health. Mathematical modeling is an important tool to assess control interventions and determine how different factors affect disease transmission. In the Chagas disease transmission cycle, the application of mathematical modeling techniques to study the role of dogs in disease epidemiology and control has not been fully understood. The purpose of this study was to review mathematical models that investigated the role of dogs in Chagas disease transmission. We examine the modeling approaches used, assess their contribution to understanding dogs’ role in Chagas disease transmission and control, and discuss their strengths and limitations. We identified ten peer-reviewed articles. Five of the ten reviewed articles focused on evaluating the effectiveness of intervention measures to control disease transmission and three focused on estimating disease transmission risk. The reviewed studies show that dogs are not only at high risk of infection but also amplify the spread of infections in endemic areas. Moreover, these studies have demonstrated that eliminating infected dogs from households or frequent use of insecticide could be sufficient to nearly interrupt disease transmission. ABSTRACT: Chagas disease is a zoonotic vector-borne disease caused by the parasite Trypanosoma cruzi, which affects a variety of mammalian species across the Americas, including humans and dogs. Mathematical modeling has been widely used to investigate the transmission dynamics and control of vector-borne diseases. We performed a scoping review of mathematical models that investigated the role of dogs in T. cruzi transmission. We identified ten peer-reviewed papers that have explicitly modeled the role of dogs in Chagas transmission dynamics. We discuss the different methods employed in these studies, the different transmission metrics, disease transmission routes, and disease control strategies that have been considered and evaluated. In general, mathematical modeling studies have shown that dogs are not only at high risk of T. cruzi infection but are also major contributors to T. cruzi transmission to humans. Moreover, eliminating infected dogs from households or frequent use of insecticide was shown to be effective for curtailing T. cruzi transmission in both humans and dogs. However, when insecticide spraying is discontinued, T. cruzi infections in dogs were shown to return to their pre-spraying levels. We discuss the challenges and opportunities for future modeling studies to improve our understanding of Chagas disease transmission dynamics and control.