Household risk factors associated with canine leishmaniasis in Fortaleza, northeastern Brazil: Environmental, social, dog characteristics, and exposure to canine Ehrlichia spp

Canine leishmaniasis (CanL) and canine monocytic ehrlichiosis (CME) are enzootic in Brazil. Although studies have identified risk factors associated with <i>Leishmania</i> seropositivity, very few have combined environmental, social, and dog characteristics, including exposure to other vector-borne pathogens such as <i>Ehrlichia canis</i>, the primary agent of CME in Brazil. In this cross-sectional study, we assessed risk factors associated with <i>Leishmania</i> seropositivity in Fortaleza, Brazil, including dog characteristics, exposure to <i>E. canis</i>, family socioeconomic status, and environmental factors, using univariate chi-squared tests for independence and multivariable random forest models. Antibodies to <i>Leishmania</i> and <i>Ehrlichia</i> were assessed using a chromatographic immunoassay and a rapid ELISA, respectively. In total, 656 dogs were included, with 21.6 % of them being positive for <i>Leishmania</i>. Large dogs and dogs from families in social stratum 7 were more likely to be exposed to <i>Leishmania</i>. Random forest classification models with acceptable discrimination (∼0.65) consistently showed that sleeping outside and household social class had the highest variable importance, regardless of the methods used to impute missing explanatory data. <i>Ehrlichia</i> exposure status, along with environmental (backyard type and presence of cats) and dog variables (fur length, deworming frequency, and tick infestation), ranked among the top ten variables in all models. In conclusion, sleeping outdoors and lower social strata were the most relevant risk factors for <i>Leishmania</i> seropositivity in dogs from Fortaleza. Large-scale studies are needed to evaluate whether these variables are risk factors for L. <i>infantum</i> exposure in other areas where CanL is endemic, possibly also incorporating more human and vector data.