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A five-year prospective study of cutaneous leishmaniasis in an endemic area of Brazil revealed an annual incidence of disease of 8.1 per 1000 inhabitants and a prevalence of 14.9%. The disease fluctuated as a series of mini-epidemics. Most disease occurred in individuals who were 10-30 years of age. Mucosal disease occurred in 2.7% of patients with primary lesions and occurred a median of six years after this lesion. Disease was more common in males, in those with either large or multiple antecedent skin lesions, and in those with incomplete antimony therapy for the primary lesions. An ELISA was positive in 85% of those tested during the first two years after the primary lesion and remained positive for five to 40 years in 27% of patients. Skin testing was positive in 96% of patients with recent lesions and remained positive in 70% of patients. All patients with mucosal disease had positive serological and skin tests.

Background: Leishmaniasis remains a serious public health problem in several parts of the developing world. Effective prophylactic measurements are hampered by imprecise comprehension of different aspects of the disease, including its immunoregulation. A better comprehension of immunoregulation in human VL may be useful both for designing and evaluating immunoprophylaxis.

A protective or deleterious role of CD8+T cells in human cutaneous leishmaniasis (CL) has been debated. The present report explores the participation of CD8+T cells in disease pathogenesis as well as in parasite killing. CD8+T cells accumulated in CL lesions as suggested by a higher frequency of CD8+CD45RO+T cells and CD8+CLA+T cells compared with peripheral blood mononuclear cells. Upon Leishmania braziliensis restimulation, most of the CD8+T cells from the lesion expressed cytolytic markers, CD107a and granzyme B. Granzyme B expression in CL lesions positively correlated with lesion size and percentage of TUNEL-positive cells. We also observed a significantly higher percentage of TUNEL-positive cells and granzyme B expression in the biopsies of patients showing a more intense necrotic process. Furthermore, coculture of infected macrophages and CD8+T lymphocytes resulted in the release of granzyme B, and the use of granzyme B inhibitor, as well as z-VAD, Fas:Fc, or anti-IFN-γ, had no effect upon parasite killing. However, coculture of infected macrophages with CD4+T cells strongly increased parasite killing, which was completely reversed by anti-IFN-γ. Our results reveal a dichotomy in human CL: CD8+ granzyme B+T cells mediate tissue injury, whereas CD4+IFN-γ+T cells mediate parasite killing.

Various factors have been associated with a predisposition to the development of clinical American visceral leishmaniasis (AVL). However, little information is available about the factors that predispose to asymptomatic infection. To identify the risk factors associated with asymptomatic infection, a study was carried out between July 1997 and June 1998 on children aged 0-5 years in the districts of Vila Nova and Bom Viver in the municipality of Raposa in the island of São Luís, State of Maranhão, Brazil. A questionnaire containing socioeconomic, demographic and epidemiological data was used. The delayed-type hypersensitivity (DTH) test was carried out on 639 children in the first phase, and on 572 in the second, 7 months after the first survey, using Leishmania amazonensis antigen. Infection was determined by enzyme-linked immunosorbent assay (ELISA) in 638 children during the first phase, and in 572 during the second. Six outcome measures were used: initial prevalence, final prevalence and incidence, each determined by DTH and ELISA. The incidence of infection was 10.8% when determined by DTH and 28.5% when determined by ELISA. After adjustment for confounding variables using Cox regression, infection by L. chagasi was associated with child's age (> or = 2 years), location of the dwellings (Vila Nova) and reporting of relatives with AVL. Bathing outside the house and playing outdoors between 18:00 and 20:00 were identified as risk factors in some analyses but not in others. Presence of intra- and peridomestic Lutzomyia sandflies and animals such as dogs or chickens in the house or in the neighbourhood appeared as risk factors in some analyses but in others they unexpectedly seemed to protect from infection. Malnutrition was not found to be associated with infection.

An epidemiological cross-sectional study of 207 patients with leprosy disease, was undertaken between August 1998 to november 2000, aiming at evaluating the socioeconomic, demographic and ambiental profiles of the patients as well as physical incapacity due to the disease. The study was performed in the municipality of Buriticupu-Maranh o state, a hiperendemic leprosy area in the Amazonian Maranh o. The level of incapacity was assessed from parameters established by the Brazilian Health Minister. The clinical evaluation and the results of the physical tests were registered in a standardized form. It was observed a predominance of married people (45,9%), with low level of education (56%), being lend workers (40,1%), with familiar income to the minimum wage (76,3%), aged from 14 to 44 years (63,3%), males (60,9%) and brown (67,6%); 44% living in mud huts, 82,6% deposited their excrements in cesspits and 63,8% do not treat the drinking water, 58% utilized well-water and 51,7% do not use treated water for ingestion. The most affected segments of the body were the feet (62,3%), eyes (51,2%) end hands (7,2%), being the higher percentage of physical incapacitaties found among the patients bearing the borderline form of the disease (93%) mainly hands and feet, and in the virchowian form greatest frequency of eyes incapacities. It is concluded that the hyperendemicity associated with the precarious socioeconomic conditions and with a high level of physical incapacities may be involved with the living quality of the patients.

We evaluated the use of polymerase chain reaction (PCR) for diagnosis of mucosal leishmaniasis (ML) in an endemic area in Acre, Brazil, where Leishmania braziliensis is present. Leishmania DNA was detected 34 of 35 cases, yielding a positivity rate of 97.1%, which was higher than the positivity rates for all of the other diagnostic methods studied, namely Montenegro skin test (MST), anti-Leishmania serological testing and microscopic examination of lesion biopsy specimens. These findings have led us to propose guidelines for the diagnosis of ML that use PCR as the principal method of parasitological confirmation of cases.

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