Canine visceral leishmaniasis in urban and rural areas of Northeast Brazil.

The purpose of this study was to determine the clinical and laboratory profiles of canine leishmaniasis in two distinct areas. Dogs from urban and rural areas were examined. The population studied in the metropolitan area included 54 dogs. Of these, 20 (37%) animals did not present with any signs suggestive of visceral leishmaniasis (VL). Among these, only eight were confirmed negative by ELISA (rK39 and CE) and 12 dogs, clinically negative for leishmaniasis, were seropositive by ELISA (rK39 and CE). Thinness, conjunctivitis and onychogryphosis were the most frequent clinical signs in the urban areas, followed by crusty lesions, alopecia, ulcerated lesions, hyperkeratosis and exfoliation. In the metropolitan area human VL cases occurred mainly in 1991, 1992, 1999 and 2000. In the rural areas the ELISA rK39 test detected a seroprevalence of 11.3% and ELISA CE (Leishmania crude extract) of 20.6%. Thirty-nine dogs were examined 6 months after the first visit. Serological exams using rK39 antigen showed seroconversion of only one dog, whereas Leishmania CE showed seroconversion of 13 (33.4%) dogs. In this rural environment 83.3% of the positive dogs were asymptomatic. Lutzomyia intermedia and Lu. longipalpis were the most predominant sandfly vector species. Amastigotes were identified in spleen and liver fragments of symptomatic necropsied animals. PCR amplification of DNA isolated from promastigote culture indicated that the species was Leishmania chagasi. This finding suggests that delayed diagnosis and euthanasia of potentially infectious animals may occur with an increased transmission risk to sandflies and subsequently to humans.

An emerging peri-urban pattern of infection with Leishmania chagasi, the protozoan causing visceral leishmaniasis in northeast Brazil.

Peri-urban visceral leishmaniasis (VL) caused by Leishmania chagasi is emerging in a new epidemiologic pattern in Brazilian cities. We studied peri-urban VL in endemic neighborhoods surrounding Natal, Brazil, identified through hospitalized individuals with VL. Clinical and environmental information obtained for 1106 members of 216 families living in endemic neighborhoods enabled us to identify 4 groups: VL: individuals with current or prior symptomatic visceral leishmaniasis (n = 135); DTH+: individuals with positive delayed-type hypersensitivity response with no history of VL (n = 390); Ab +: individuals with negative DTH response and seropositive (n = 21); DTH -: individuals with negative DTH and seronegative (n = 560). The mean +/-SD age of VL was 9.3+/-12.3 y. The gender distribution was nearly equal below age 5, but skewed toward males at higher ages. Acutely infected VL subjects had significantly lower hematocrits, neutrophils, and eosinophils than other categories. AB+ subjects also had lower eosinophil counts than others, a possible immune marker of early infection. VL was not associated with ownership of dogs or other animals, raising the question whether the reservoir differs in peri-urban settings. This new pattern of L. chagasi infection enables us to identify epidemiological and host factors underlying this emerging infectious disease.

Changing epidemiology of American cutaneous leishmaniasis (ACL) in Brazil: a disease of the urban-rural interface.

American cutaneous leishmaniasis (ACL) was first reported from the south-western region of the state of Rio Grande do Norte in 1987. São Miguel municipality and adjacent areas have accounted for 90% of the American cutaneous leishmaniasis cases in the region since then. A population survey conducted in São Miguel and adjacent areas was undertaken to identify individuals with a history of ACL. The incidence of ACL, distribution by age and gender, clinical characteristics, family clustering, relationship to animals, association with skin test responses, and development of mucosal lesions were determined. Males and females were equally likely to be infected by Leishmania. Thirty-eight percent of the individuals tested were found to be Montenegro skin test positive. No difference in the Montenegro skin test was observed with gender, but the response increased with age. Among the 140 ACL cases treated in a 4-year period in São Miguel, five (3.6%) developed mucosal involvement. Sandflies capable of transmitting Leishmania were captured inside households and in the areas surrounding them. The high density of sandfly species potentially able to transmit Leishmania species and the age distribution of cases of cutaneous leishmaniasis suggest that transmission of the parasite occurred inside or in close proximity to houses.