Chagas Disease at the Canine-Wildlife-Human-Vector Interface

摘要

The hemoflagellate protozoan Trypanosoma cruzi is the etiologic agent of Chagas disease, and infects humans, nonhuman primates, dogs, and other wild and domestic mammalian species. Active transmission of T. cruzi occurs throughout the Americas, including the southern USA, where infected hematophagous triatomine "kissing bug" vectors (Fig. 1) and wildlife reservoirs co-occur.1 Infection can occur through the introduction of infectious triatomine feces to skin lesions during or shortly after blood feeding. Oral transmission to animals may result from consumption of infected bugs or infected prey species.1 Congenital transmission has been documented in humans, canines, and other animals.1 T. cruzi genetic strain differences occur throughout the Americas,2 where parasite discrete typing units (DTUs) TcI-TcVI circulate and may be associated with different reservoir hosts, vector species, and variation in disease outcome. Infected individuals do not always develop clinical disease;1 and prognosis in initially asymptomatic individuals is largely unknown. In the USA, clinical T. cruzi infection in dogs is most commonly associated with cardiac disease.13 Dogs are important hosts throughout the Americas, and in some cases serve as sentinels of human diseaserisk across a landscape.4 Diagnosis of Chagas disease is most commonly based on clinical suspicion and antibody detection, but diagnostic tests are imperfect and confirmation of antibody status is best derived from the results of more than one independent assay, which is usually impracticable. Chagas disease is a notifiable infectious disease for humans in four states, including Texas, Tennessee, Massachusetts, and Arizona. Using a One Health approach, we have conducted epidemiological studies of T. cruzi in vectors, dogs, wildlife, and humans, with a focus on the high-risk state of Texas in order to characterize transmission cycles, identify risk factors, and identify points for management interventions to reduce disease risk; highlights are reviewed below.