Dogs as reservoirs for Leishmania braziliensis.

To the Editor: I have read the review by Sousa and Pearson (), which provides a fascinating historical account of the Great Drought and the smallpox epidemic of the 1870s and their association with the emergence of cutaneous leishmaniasis in Ceará, Brazil. In their review, the authors went back to the 19th century, remembering the hard years experienced by those who faced the Great Drought, which prompted the immigration of thousands of persons from Ceará to the Amazon region, and a devastating smallpox epidemic, which resulted in the death of >100,000 persons. Later, they returned to the present situation of cutaneous leishmaniasis in Brazil.

I would like to address the role of dogs as reservoirs of Leishmania (Viannia) braziliensis. Sousa and Pearson stated that “no animal reservoir other than dogs has been identified in Ceará” and that “a sylvatic reservoir has not been identified for L. (V.) braziliensis in Ceará and other areas,” concluding that “dogs appear to be the most important reservoir in domestic and peridomestic transmission.”

Conversely, recent studies have indicated that rodents and other small mammals are the primary reservoirs for L. (V.) braziliensis () and that, so far, no strong evidence indicates that dogs could act as reservoirs for this parasite (,). The finding of dogs infected by L. (V.) braziliensis in leishmaniasis-endemic areas is expected because they are susceptible to this parasite and are often exposed to phlebotomine sandflies. However, this finding does not imply that dogs are important reservoirs. Indeed, they represent a poor source of L. (V.) braziliensis (). For these reasons, dogs cannot be incriminated as the most important reservoirs in the domestic and peridomestic transmission cycles of L. (V.) braziliensis.

In Response: We agree with most points raised by Dantas-Torres (). However, so far our statement related to the reservoir(s) of Leishmania (Viannia) braziliensis () is correct for Ceará. Oliviera-Lima () conducted a case–control study that definitively incriminated dogs as a reservoir host of L. (V.) braziliensis in Baturite, Ceará. He showed that infected dogs in households increased the risk for infection with L. (V.) braziliensis by 3.2-fold among resident children. The risk increased to 6-fold when infected dogs had leishmaniasis-like skin lesions. Additionally, his observations suggested that animals other than dogs might be involved. In another study, Santana () examined 272 small mammals (213 rodents and 59 marsupials) in the same area; tissue culture and hamster inoculation showed none to be infected with L. (V.) braziliensis, although some cultures were contaminated by fungi and bacteria. On the basis of these findings, a sylvatic reservoir for L. (V.) braziliensis has not been identified in Baturite, Ceará. However, Brandão-Filho et al. found that rodents in Pernambuco State, Brazil, were infected with L. (V.) braziliensis and stated that they were the primary reservoir (). We concur with Lainson and Shaw () and conclude that information about mammalian reservoirs of L. (V.) braziliensis is incomplete.