Domestic dogs and cats as sources ofTrypanosoma cruziinfection in rural northwestern Argentina

Abstract

The reservoir capacity of domestic cats and dogs forTrypanosoma cruziinfection and the host-feeding patterns of domesticTriatoma infestanswere assessed longitudinally in 2 infested rural villages in north-western Argentina. A total of 86 dogs and 38 cats was repeatedly examined forT. cruziinfection by serology and/or xenodiagnosis. The composite prevalence of infection in dogs (60%), but not in cats, increased significantly with age and with the domiciliary density of infectedT. infestans. Dogs and cats had similarly high forces of infection, prevalence of infectious hosts (41–42%), and infectiousness to bugs at a wide range of infected bug densities. The infectiousness to bugs of seropositive dogs declined significantly with increasing dog age and was highly aggregated. Individual dog infectiousness to bugs was significantly autocorrelated over time. DomesticT. infestansfed on dogs showed higher infection prevalence (49%) than those fed on cats (39%), humans (38%) or chickens (29%) among 1085 bugs examined. The basic reproduction number ofT. cruziin dogs was at least 8·2. Both cats and dogs are epidemiologically important sources of infection for bugs and householders, dogs nearly 3 times more than cats.