The protozoan Leishmania chagasi can cause disseminated, fatal visceral leishmaniasis (VL) or asymptomatic infection in humans. We hypothesized that host genetic factors contribute to this variable response to infection. A family study was performed in neighborhoods of endemicity for L. chagasi near Natal in northeastern Brazil. Study subjects were assessed for the presence of VL or asymptomatic infection, which was defined by a positive delayed-type hypersensitivity (DTH) skin test response to Leishmania antigen without disease symptoms. A genomewide panel of 385 autosomal microsatellite markers in 1254 subjects from 191 families was analyzed to identify regions of linkage. Regions with potential linkage to the DTH response on chromosomes 15 and 19, as well as a novel region on chromosome 9 with potential linkage to VL, were identified. Understanding the genetic factors that determine whether an individual will develop symptomatic or asymptomatic infection with L. chagasi may identify proteins essential for immune protection against this parasitic disease and reveal strategies for immunotherapy or prevention.

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.

-Natural environmental changes or those resulting from anthropic factors and their impact on infectious diseases have been evaluated in several studies. The objective of this work was to analyze the correlation between the anthropic environment, phlebotomine and leishmaniases in Rio Grande do Norte State, in Northeast Brazil. Information relative to the distribution of vector species in visceral and tegumentary leishmaniasis areas was associated to the record of cases notifi ed by Public Health organs. The analysis suggests associations between the vector species and distribution of the disease with demographic and physionomic characteristics, disorderly growth in the metropolitan area, living conditions and environmental degradation of the Eastern Littoral, the principal area of notifi ed visceral leishmaniasis cases.KEY WORDS: Sand fl y, public health RESUMO -As alterações ambientais, naturais ou resultantes de ações antrópicas e seu impacto sobre as doenças infecciosas têm sido avaliados em diversos estudos. Com o objetivo de analisar possíveis correlações entre o ambiente antrópico, fl ebotomíneos (Diptera: Psychodidae) e leishmanioses no Rio Grande do Norte, Nordeste do Brasil, foram associadas informações relativas à distribuição de espécies vetoras em áreas de leishmaniose visceral e tegumentar ao registro de casos notifi cados pelos órgãos de saúde pública. A análise aponta para a existência de associações entre as espécies vetoras e distribuição da doença com características demográfi cas, fi sionômicas, crescimento desordenado da área metropolitana, condições de vida e degradação ambiental do Litoral Oriental, principal área de notifi cação de casos de leishmaniose visceral. PALAVRAS-CHAVE: Inseto vetor, saúde públicaNos últimos dez anos, as alterações ambientais, climáticas ou resultantes de ações antrópicas, e possíveis refl exos na distribuição de doenças tropicais têm sido analisados por diversos autores (Ambroise- Thomas 2000, Curtis et al. 2000, Patz et al. 2000, Petney 2001, Molineux 2006. As mudanças globais e a avaliação do impacto sobre a saúde humana têm sido foco de atenção em comitês e órgãos internacionais que analisam o sistema climático terrestre e as repercussões para a saúde humana (WHO 1995).Destruição de habitats, mudanças no padrão demográfi co das cidades, costumes, nível sócio-econômico, qualidade dos serviços de saúde, educação etc. isoladamente ou em associação, aproximam hospedeiros defi nitivos e intermediários, vetores e parasitos e determinam mudanças nos níveis endêmico ou epidêmico de doenças infecciosas (Ambroise- Thomas et al. 2000, Curtis et al. 2000, Patz et al. 2000.A manutenção de uma endemia em determinada área, particularmente aquelas transmitidas por vetores, depende da presença de populações de espécies envolvidas na cadeia de transmissão (agentes etiológicos, reservatórios e vetores) e condições ambientais favoráveis ao seu desenvolvimento. Tais condições são naturalmente encontradas, como podem ser propiciadas pelas alterações causadas pelo homem, lev...

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Leishmania infantum infection in humans and dogs can evolve with a wide range of clinical presentations, varying from asymptomatic infections to visceral leishmaniasis. We hypothesized that the immune response elicited by L. infantum infection could modulate whether the host will remain asymptomatic or progress to disease. A total of 44 dogs naturally infected with L. infantum were studied. Leishmania burden was estimated in the blood and spleen by qPCR. The expression of IFN-γ, TNF-α, IL-10 and Iron Regulatory Protein 2 (IRP2) were determined in the spleen by quantitative PCR. Sera cytokines were evaluated by ELISA. Dogs were grouped in quartiles according parasite burden. Increased expression of IFN-γ and TNF-α was associated with reduced Leishmania burden, whereas increased IL-10 and IRP2 expressions were associated with higher Leishmania load. Increased plasma albumin and IFN-γ expression explained 22.8% of the decrease in parasite burden in the spleen. These data confirm that lower IFN-γ response and higher IL-10 correlated with increased parasite load and severity of the visceral leishmaniasis in dogs. The balance between the branches of immune response and the intracellular iron availability could determine, in part, the course of Leishmania infection.