Canine species are considered an important reservoir of T. cruzi in the domestic cycle carrying a risk for human population; because, these animals living in close proximity to humans are within the transmission and maintenance cycles of the parasite and serve as a source of food for insect vectors 2, 15. Reservoirs may be considered as a complex ecological system consisting of one or more species responsible for maintaining a given parasite species in nature. The infestation of houses and peridomestic areas is considered to be a major risk factor for Chagas disease transmission. Dog infection with T. cruzi is an important veterinary health concern in many countries of South America and more recently in the United States, in which the seroprevalence of specific anti-T. cruzi antibodies has also been reported 16, 17. Infected vectors have been reported in Texas military kennels, where some dogs showed clinical signs compatible with Chagas disease infection 18. From the veterinary point of view, it is also important to consider that dogs are susceptible to acquire American trypanosomiasis characterized by heart conditions, such as electrical conduction disturbances, and ventricular and supraventricular arrhythmias, as well as secondary signs such as ascites, respiratory distress, thoracic effusion, and cyanosis. Texas is a high-risk state for transmission of the parasite to dogs, considering the diversity of triatomine vectors, reservoir hosts, and previous documentation of canine disease 19. A high seroprevalence of canine infection with T. cruzi has been detected from southeastern USA States of Louisiana, Oklahoma, Georgia, and Texas; showing the epidemiological role of the domestic dog 20. In canines from countries in Latin American, various reports showed seroprevalences from 24% to 65% 21, 22. The presence of infected canine species increases the risk of transmission of parasites to vectors, and thus the probability of infection in humans. Generally, canine infections are more prevalent than human infections, a fact likely related to oral T. cruzi transmission, a more efficient route of infection and apparently common to many mammals 23, and also the fact that dogs often sleep near houses and may come in greater contact with peridomiciliary vectors.
It has been considered that separating domestic animals, mainly dogs, from people can significantly reduce transmission to humans 24. The fact that there is a high prevalence of canine infections represents a warning signal that should lead to the planning and execution of effective vector control strategies, i.e. it is essential to carry out fumigation strategies of areas infested with triatomines, to exterminate them and thus eliminate transmission 25.
In studies carried out by Meyer et al. (2017) 26 in along border Texas-México, the dogs showed an overall apparent seroprevalence of 7.4-18.9%. This values are similars to that described in dogs of endemic populations for Chagas in Peru (12.3%) 27, Argentina (45.6%) 11, Panama (11.1%) 28, Costa Rica (27.7%) 29, Yucatan State, Mexico (9.8%-14.4%) 30 and Mexico State, Mexico (10%-15.8%) 31.
The dogs are targeted in a Chagas’ disease control strategy, because they are considered natural sentinels 26. These animals generally inhabit a defined territory; are accessible, easy to enumerate and capture, and their population allows representative sampling 31.