Leishmania infantum chagasi in northeastern Brazil: asymptomatic infection at the urban perimeter.

Visceral leishmaniasis (VL) is endemic in large cities in Brazil, including Natal. We determined the prevalence of asymptomatic human infection with Leishmania infantum chagasi and associated environmental risks around Natal. Infection was detected by Leishmania skin test (LST) and anti-leishmanial antibodies in humans and anti-leishmanial antibodies in dogs. Amongst 345 humans, 24.6% were seropositive, and 38.6% were LST-positive. Prevalence of positive serology was similar in both sexes and across all ages. However, positive LST responses increased with age, suggesting that LST is long-lasting and cumulative. Multinomial logistic analysis showed that LST response varied with location (P = 0.007) and that males were more frequently LST-positive (P = 0.027). Indicators of lower socioeconomic status associated significantly with human infection. Furthermore, there was geographic coincidence of seropositive humans and dogs (r = 0.7926, P = 0.011). These data suggest that dog and human L. i. chagasi infection are intimately interrelated in environmental conditions associated with low income.

Leptospirosis in a subsistence farming community in Brazil.

Leptospirosis has been reported in rural areas of Brazil. However, there is limited information about the exposure risk or the risk of Leptospira infection for rural-based populations. A cross-sectional study was carried out in order to determine the prevalence and risk factors for prior Leptospira infection in a rural subsistence farming region of the state of Rio Grande do Norte, an area in which outbreaks of leptospirosis have occurred. Among 290 individuals enrolled, 44 (15.2%) had anti-Leptospira IgM antibodies as determined by IgM ELISA. Infection tended to occur with activities related to the rice fields (P=0.08). Our findings indicate that Leptospira infection occurs even in years of low rainfall, and may have an important impact among poor rural-based subsistence farmers in Brazil. Additional studies are needed to characterize the mode of transmission in this region.

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.