Dogs as Reservoirs for Leishmania braziliensis

To the Editor: I have read the review by Sousa and Pearson (1), 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 Ceara, 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 Ceara 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.

based on the consideration that R. aeschlimannii is usually found in ticks of the genus Hyalomma, primarily in H. marginatum (1). Therefore, 1 of the PCRs amplifi ed a fragment of the Hyalomma tick mitochondrial cytochrome oxidase I gene and the other a fragment of the internal transcribed spacer 2 (7).
The Earlier, R. aeschlimannii had been detected in sub-Saharan and North Africa, southern Europe, and southwestern Russia (8). Therefore, the area of Zerbst, the middle of Germany, marks the northernmost point of R. aeschlimannii detection.
Hyalomma spp. ticks are distributed in Africa, the Mediterranean climatic zone of southern Europe, and in Asia. The only documented Hyalomma spp. tick in Germany was found on a human in the southern part of the country (Lake Constance area) in May 2006, but the possibility of tick transportation from Spain was not ruled out (9).
Acrocephalus scirpaceus birds are migratory birds and live in central Europe from April to October and winter in sub-Saharan Africa in the region inhabited by Hyalomma spp. ticks. Therefore, it is reasonable to suggest that the Hyalomma spp. ticks that we examined had been transported by the birds from Africa. The fact that a randomly caught bird was infested with R. aeshlimannii -infected ticks is suggestive of the intensive stream of new pathogens transported through Europe by migrating birds. The fi rst possible implication of a bird as a vector of infected ticks was proposed for Hyalomma spp. ticks infected by R. sibirica mongolitimonae (10). Until now, the role of migrating birds in distribution of tick-borne pathogens has been poorly understood (9). The changing climate and environment in central Europe may facilitate the establishment of pathogen-carrying tick species transported by birds. These new pathogens can be directly transmitted from infected birds to the species of the local fauna.

Dogs as Reservoirs for Leishmania braziliensis
To the Editor: I have read the review by Sousa and Pearson (1), 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 identifi ed in Ceará" and that "a sylvatic reservoir has not been identifi ed 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 (2) and that, so far, no strong evidence indicates that dogs could act as reservoirs for this parasite (3,4). The fi nding 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 sandfl ies. However, this fi nding does not imply that dogs are important reservoirs. Indeed, they represent a poor source of L. (V.) braziliensis (3). For these reasons, dogs cannot be incriminated as the most important reservoirs in the domestic and peridomestic transmission cycles of L. (V.) braziliensis.