Epidemiology of Ehrlichia canis in healthy dogs from the Southeastern region of the state of Rio de Janeiro, Brazil

This cross-sectional, observational, and descriptive study aims to investigate the epidemiology of Ehrlichia canis in healthy owned dogs from the Southeastern region of Rio de Janeiro, Brazil. Blood samples were collected from 390 households dogs. During the visits, an epidemiological questionnaire was filled out concerning the dogs' characteristics as well as the environments in which they lived. The variables were analyzed using a bivariate test, while the correlation analysis between the variables was performed via a phi test. The variables that had p-values lower than 0.2 in the bivariate analysis and had a low or moderate correlation were selected for the multivariate analysis. The model that had the lowest Akaike information criterion (AIC) value was retained. Among the 390 blood samples tested, 24.8% were considered positive for E. canis. The parsimonious logistic regression model presented an AIC value of 408.75 and showed three variables that favored the presence of E. canis DNA in the tested dogs: the animal's access to urban streets and neighborhoods (odds ratio [OR] = 1.91; p-value = 0.02; confidence interval [CI]: 1.14 - 3.18), tick infestation (OR = 2.01; p-value = 0.006; CI: 1.22 - 3.32), and poor hygienic conditions (OR = 2.19; p-value = 0.002; CI: 1.31 - 3.67). The model was considered well-calibrated based on the Hosmer-Lemeshow test (p = 0.39). According to the present study, dogs that have access to the street and neighborhood, are infested with ticks, and live under poor hygienic conditions are more likely to be infected with E. canis in the state of Rio de Janeiro, Brazil.