From 1977 (index case) to 2006, 87 cases of visceral leishmaniasis were confirmed in the municipality of Rio de Janeiro, Brazil, in periurban areas on the continental and coastal slopes of the Pedra Branca massif and the continental slopes of the Gericinó massif. The majority (65.5%) of the patients were more than five years old, predominantly males (61.5%), but without any difference between the sexes below the age of 14 years. The overall fatality rate was 10.4%. Two cases of visceral leishmaniasis/human immunodeficiency virus coinfection were detected. Leishmania chagasi was isolated from human and canine cases. The associations between the presence of phlebotomines and human and canine migrations, disorderly occupation involving degradation of environmental preservation areas and poor socioeconomic conditions may have created a favorable setting for the establishment and propagation of the disease. Close epidemiological surveillance associated with traditional control measures and others (active case researches, land clearing and health education), reduced the incidence of human cases from 2.8 per 100,000 inhabitants in 1981 to less than 0.01 per 100,000 since 1997. The canine infection rates decreased from 4.6% in 1984 to 1.6% in 2008. Lutzomyia longipalpis was not detected in some locations where human and canine cases occurred. In the years 2007 and 2008, no new human cases were reported, but there is a persistent and worrisome residual canine seroprevalence.

Phylogenetic studies on trypanosomatid barcode using V7V8 SSU rRNA and gGAPDH gene sequences have provided support for redefining some trypanosomatid species and positioning new isolates. The genus Leishmania is a slow evolving monophyletic group and including important human pathogens. The phylogenetic relationships of this genus have been determined by the natural history of its vertebrate hosts, vector specificity, clinical manifestations, geographical distribution and molecular approaches using different markers. Thus, in an attempt to better understand the phylogenetic relationships of Leishmania species, we performed phylogenetic analysis on trypanosomatid barcode using V7V8 SSU rRNA and gGAPDH gene sequences among a large number of Leishmania species and also several Brazilian visceral Leishmania infantum chagasi isolates obtained from dogs and humans. Our phylogenetic analysis strongly suggested that Leishmania hertigi and Leishmania equatoriensis should be taxonomically revised so as to include them in the genus Endotrypanum; and supported ancient divergence of Leishmania enriettii. This, together with recent data in the literature, throws light on the discussion about the evolutionary southern supercontinent hypothesis for the origin of Leishmania ssp. and validates L. infantum chagasi from Brazil, thus clearly differentiating it from L. infantum, for the first time.

The objectives of this study were to evaluate the occurrence of Leishmania infantum in the male and female genital tract and female mammary glands of dogs and the parasite burden and to identify histological alterations associated with this protozoan. Twenty male and 20 female Leishmania-seropositive dogs with isolation of L. infantum were examined. Tissue samples of the prepuce, glans, epididymis, testes, prostate, vulva, vagina, uterus, uterine tubes, and mammary glands were analyzed by immunohistochemistry and histopathology. For parasitological culture and in situ hybridization, samples were collected from the testis, epididymis, and uterus. Additionally, seminal fluid was aspirated from the epididymis for parasitological culture. In the genital tract, 34 (85 %) dogs, including 18 males and 16 females, were positive for Leishmania. Of these, 27 (79 %) animals were symptomatic. Leishmania was detected in the mammary glands of 13 (65 %) females. L. infantum was isolated for the first time from the seminal fluid and uterus of naturally infected dogs. The parasite burden and intensity of the inflammatory reaction were greater in the prepuce and glans of males and in the vulva and mammary glands of females. In addition to inflammation, testicular degeneration, atrophy, absence of spermatogenesis, and necrosis were observed. Detection of amastigote forms in the mammary gland lumen indicates possible elimination of this parasite in milk. The frequent parasitism observed in the genital tract of infected males and females and the viability of L. infantum in seminal fluid and uterus suggest the possibility of bidirectional venereal and vertical transmission.