Evidence of Venereal and Transplacental Transmission of Canine Visceral Leishmaniasis in Southern Brazil

Background: Zoonotic visceral leishmaniasis is a vector-borne disease caused by obligate intracellular protozoan parasites of the genus Leishmania. In South America, dogs are the primary domestic reservoir host and control measures for this disease are focused on vector-control and euthanasia of seropositive dogs. The infection occurs usually between the invertebrate host and vertebrate host; however, transmission in the absence of the vector has been reported. Ticks as the vectors of the parasite L. infantum have been mentioned and investigated by researchers. Researchers have reported new mechanisms of transmission of canine visceral leishmaniasis, such as venereal and transplacental transmission. In october 2010, a veterinary clinic of Santa Maria received one canine, female, Doberman bred, two years old, L. chagasi positive. According to the authors, this would be the first case of autochthonous leishmaniasis in the State of Rio Grande do Sul (RS), Brazil. Therefore, through epidemiological surveys, this study had the aim to clarify how the dog was infected by the parasite. Case: During the epidemiological survey was discovered that this canine positive for L. chagasi had never left the city of Santa Maria, place where it was born. However the parents of this animal were born in Sao Borja, RS, where they lived for about two months. According to the owner, both animals (male and female Doberman) were brought to Santa Maria as puppies in 2006 and since then never returned to the city of origin. Both animals were bought from different dog breeders in Sao Borja. Once in Santa Maria, the animals mated and the female gave birth to eight puppies. The owners of the puppies kept only one and the other puppies were sold to neighbors and other buyers. The canine male Doberman, four years old, had skin lesions that did not healed (especially in the hip region), difficulty in gaining weight, and nodules on the face. In the cytology of the skin lesions was observed in forms which resembling to amastigotes of Leishmania sp. Then blood was collected from the animal, aiming to perform serological tests, which confirmed the leishmaniasis. Serologic test was also performed in the female Doberman and in the puppies which were asymptomatic, but in direct contact with a symptomatic male. Serologic tests showed three animals as positive for the parasite, and they were euthanized as recommended by the Ministry of Health. Discussion: Based on data obtained we suggest that the male Doberman has came from Sao Borja town already infected with the parasite Leishmania sp., as well as it might have occurred to the female Doberman. The female may was infected during copulation (venereal infection), and then the puppies were infected. The possibility of venereal transmission in dogs was reported by researchers, when the presence of Leishmania amastigotes in testicular of symptomatic and asymptomatic dogs was observed, and in semen associated with genital lesions caused by the parasite. Since in Santa Maria there was not recorded the presence of the vector L. longipalpis, we hypothesized that the two puppies were infected with the parasite transplacentally. Researchers recently showed that canine visceral leishmaniasis has vertical transmission, because a female pregnant dog and infected with L. infantum bore positive puppies to the disease. Based on the survey and the results of epidemiological literature we concluded that this is the first case of autochthonous canine leishmaniasis recorded in Santa Maria (RS), with evidences of transplacental and venereal transmission.