Is the domestic dog (Canis familiaris) a reservoir host of American cutaneous leishmaniasis? A critical review of the current evidence.

Abstract

Abstract. Originally associated with forested areas, the transmission cycle of American cutaneous leishmaniasis (ACL) has now adapted to the domestic environment in at least 9 Latin American countries. Several studies have suggested that the domestic dog (Canis familiaris), which is already incriminated as the primary reservoir host of zoonotic visceral leishmaniasis (ZVL), may have a reservoir role in the domestic transmission of human ACL caused by Leishmania braziliensis, L. panamensis, and L. peruviana. This article reviews more than 90 studies reporting ACL infections in dogs, and concludes that as yet there is only circumstantial evidence to support that claim. Almost no data are available on the infectiousness of dogs to sandfly vectors of ACL, and there are few indications that either dog ownership or dog abundance are risk factors for ACL. Nevertheless, it has been proposed that incidence of ACL in humans could be reduced by targeting infected dogs. While this control strategy has been used for many decades against ZVL in Latin America, Europe, and Asia, there is little evidence to demonstrate its effectiveness either in theory or in practice. Particular concerns over the sensitivity and specificity of diagnostic tools, low compliance rates among dog owners, and cost-effectiveness are likely to apply equally to ACL control.The leishmaniases are a group of zoonotic diseases transmitted to humans and animals by the bite of phlebotomine sand flies (Diptera: Psychodidae). Despite their multiple etiologies, the New World leishmaniases can be divided into two broad categories: zoonotic visceral leishmaniasis (ZVL) and American cutaneous leishmaniasis (ACL).1 The latter includes localized cutaneous, mucocutaneous, and diffuse cutaneous leishmaniasis. Whereas ZVL is almost exclusively caused by Leishmania chagasi (L. infantum), ACL is caused by several Leishmania species, of which L. braziliensis is the most widespread. Many sandfly species have been incriminated as vectors of ACL throughout its geographic range, but reservoir hosts have only been identified for L. amazonensis, L. mexicana, L. guyanensis, and L. panamensis, and are unknown or unproven for both L. braziliensis and L. peruviana. 1 Originally associated with forested areas, 2 the transmission cycle of ACL has now adapted to the domestic environment due to deforestation and urbanization. 3,4 The transition from sylvatic to domestic transmission cycle was further encouraged by the lack of a specific leishmaniasis control strategy, and the discontinuation of intervention campaigns designed for other infectious diseases, e.g., malaria. 5,6

Leishmania (Viannia) braziliensis em cães naturalmente infectados

“…Apesar de ser uma zoonose originalmente silvestre, a LTA causada pela Leishmania (Viannia) braziliensis tem sido descrita por diversos autores ocorrendo em ambientes domésticos, tendo sido aventada a possibilidade de que animais domésticos e peridomésticos, e em especial o cão, estariam funcionando como importantes fontes de infecção nesse locais 2 8 13 . Vários questionamentos ainda permanecem quanto ao verdadeiro papel do cão nessa nova adaptação do ciclo de transmissão 16 .Pouco também se conhece sobre os aspectos clínicos, parasitológicos e imunológicos do curso da infecção pela L. braziliensis em cães, sendo portanto, necessários mais estudos visando elucidar esses aspectos, que contribuirão não só para o diagnóstico precoce dos casos caninos bem como para o esclarecimento do papel dessa espécie animal na epidemiologia da LTA.O presente trabalho teve como objetivo estudar casos de cães com lesão sugestiva de LTA provenientes do Município de Maricá (Rio de Janeiro), descrevendose a apresentação das lesões e correlacionando-as com os resultados parasitológicos e sorológicos. …”

“…Apesar de ser uma zoonose originalmente silvestre, a LTA causada pela Leishmania (Viannia) braziliensis tem sido descrita por diversos autores ocorrendo em ambientes domésticos, tendo sido aventada a possibilidade de que animais domésticos e peridomésticos, e em especial o cão, estariam funcionando como importantes fontes de infecção nesse locais 2 8 13 . Vários questionamentos ainda permanecem quanto ao verdadeiro papel do cão nessa nova adaptação do ciclo de transmissão 16 .…”

“…Vários questionamentos ainda permanecem quanto ao verdadeiro papel do cão nessa nova adaptação do ciclo de transmissão 16 .…”

Photodynamic antimicrobial chemotherapy (PACT) for the treatment of malaria, leishmaniasis and trypanosomiasis

“…The parasite has different life forms in the human host and in sand fly vectors, i.e., amastigotes, which are small and oval and promastigotes, which are longer flagellated forms of the parasite. Domestic dogs are also infected by Leishmania parasites and these animals are a reservoir for human leishmaniasis (44).…”

Leishmania (Viannia) braziliensis infection in two Colombian dogs: a note on infectivity for sand flies and response to treatment

“…There is no doubt that dogs play an essential role in the peridomestic transmission of visceral leishmaniasis (10), yet only risk factor analyses and isolation of Leishmania from lesions have suggested that they could play a role in American cutaneous leishmaniasis (1,7,11), and consequently confirmatory studies are still pending. We report on two cases of canine leishmaniasis in adult male, mongrel dogs residing in different endemic areas of cutaneous leishmaniasis in the Colombian Pacific coast.…”