Is There an Association Between Exposure to Cats and Occurrence of Visceral Leishmaniasis in Humans and Dogs?

The domestic dog is considered the main reservoir of visceral leishmaniasis (VL) in urban areas, but the identification of cats infected by Leishmania suggests the possibility of these animals also acting as reservoirs. The incrimination of a species as reservoir requires the accumulation of epidemiological evidence on the co-occurrence between such species and the infection in question. This is a systematic review of epidemiological studies evaluating the association between exposure to cats and occurrence of VL in humans (HVL) or dogs (CVL). Among the six studies addressing CVL, one showed a higher chance of CVL in the presence of cats, one showed an inverse relationship between the presence of cats and CVL, and four were inconclusive. Among the four studies evaluating HVL, three were inconclusive, and one showed an association between the presence of cats and HVL among patients with renal transplantation. The inconsistency of the results, associated to the methodological weaknesses of the studies analyzed, does not allow a firm conclusion that there is co-occurrence between exposure to cats and VL. Methodologically robust studies should be performed to elucidate the role of cats in VL transmission.