Abstract
Leishmaniasis is a vector-borne disease withLeishmania chagasibeing the etiological agent of canine visceral leishmaniasis in South America. Canine venereal tumor is a transplantable round cell tumor of histiocytic origin which is mostly observed in sexually active male and female intact dogs. It has been shown thatLeishmaniaamastigotes have higher tropism for the canine male genital tract tissues and venereal leishmaniasis transmission has been documented in dogs but, to date, a canine venereal tumor-dependent transmission route has not been fully demonstrated. In this report, a 10-year-old, mixed breed, intact female dog presented a vaginal venereal transmissible tumor but no other clinical abnormalities otherwise. Unexpectedly, tumor tissue imprint smears examination revealedLeishmaniasp. amastigotes within infiltrating macrophages. In addition to the cytological direct identification, the protozoan was confirmed within the neoplastic tissue by means of immunohistochemistry and polymerase chain reaction. This report illustrates an asymptomaticLeishmaniasp. infection that may have started on or from the canine venereal tumor tissue, the latter option further supporting previous evidence of such an alternative vector-independent route of transmission for canine visceral leishmaniasis in areas where these diseases coexist.
Highlights
Leishmaniasis is an anthropozoonotic disease with wide geographic distribution, affecting humans, dogs, and several wildlife species, and is caused by the obligate intracellular protozoa belonging to the genus Leishmania
Leishmaniasis is a vector-borne disease with Leishmania chagasi being the etiological agent of canine visceral leishmaniasis in South America
It has been shown that Leishmania amastigotes have higher tropism for the canine male genital tract tissues and venereal leishmaniasis transmission has been documented in dogs but, to date, a canine venereal tumor-dependent transmission route has not been fully demonstrated
Summary
Leishmaniasis is an anthropozoonotic disease with wide geographic distribution, affecting humans, dogs, and several wildlife species, and is caused by the obligate intracellular protozoa belonging to the genus Leishmania. CanVL has been previously identified concurrently with canine transmissible venereal tumor as well as Leishmania sp. In regard to the synergistic nature of systemic parasitism and neoplasia, it has been proposed that concurrent diseases may occur secondary to the CanVL-driven immune impairment or, alternatively, neoplastic diseases could hamper the immune system, triggering the onset of clinical leishmaniasis in an already infected but asymptomatic dog [12, 13]. The coexistence in the same lesion of CTVT and Leishmania has been previously attributed to the systemic dissemination of the latter [10], where amastigote-laden macrophages get recruited into the CTVT tissue. It has been suggested that Leishmania amastigotes-laden neoplastic CTVT cells can represent an alternative mode of transmission of canine leishmaniasis in areas where these diseases coexist [11, 12, 15]
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