BACKGROUND Leishmaniasis is a neglected zoonosis caused by parasites of Leishmania spp. The main drug used to treat cutaneous leishmaniasis (CL) is the antimoniate of meglumine. This drug, which has strong adverse and toxic effects, is usually administered intravenously, further complicating the difficult treatment. Factors such as Leishmania gene expression and genomic mutations appear to play a role in the development of drug resistance. OBJECTIVES This systematic review summarises the results of the literature evaluating parasite genetic markers possibly associated with resistance to pentavalent antimony in CL. METHODS This study followed PRISMA guidelines and included articles from PubMed, SciELO, and LILACS databases. Inclusion criteria were studies that (i) investigated mutations in the genome and/or changes in gene expression of Leishmania associated with treatment resistance; (ii) used antimony drugs in the therapy of CL; (iii) used naturally resistant strains isolated from patients. The Joanna Briggs Institute Critical Appraisal Checklist was used to assess article quality and risk of bias. FINDINGS A total of 23 articles were selected, of which 18 investigated gene expression and nine genomic mutations. Of these 23 articles, four examined gene expression and genomic mutations in the same samples. Regarding gene expression, genes from the ABC transporter protein family, AQP1, MRPA, TDR1 and TRYR were most frequently associated with drug resistance. In one of the articles in which mutations were investigated, a mutation was found in HSP70 (T579A) and in three articles mutations were found in AQP1 (A516C, G562A and G700A). A limitation of this review is that in most of the included studies, parasites were isolated from cultured lesion samples and drug resistance was assessed using in vitro drug susceptibility testing. These approaches may not be ideal for accurate genetic evaluation and detection of treatment failure. MAIN CONCLUSIONS The development of further studies to evaluate the genetic resistance factors of Leishmania spp. is necessary to elucidate the mechanisms of the parasite and improve patient treatment and infection control. spp CL (CL meglumine effects intravenously PubMed SciELO databases i (i andor or ii (ii iii (iii patients bias 2 selected 1 family AQP MRPA TDR HSP HSP7 T579A TA T (T579A A516C, A516C AC C (A516C GA G G700A. G700A . G700A) testing failure control

BACKGROUND Visceral leishmaniasis (VL) is a tropical neglected disease with high associated rates of mortality. Several studies have highlighted the importance of the intestinal tract (IT) and gut microbiota (GM) in the host immunological defense. Data in the literature on parasite life cycle and host immune defense against VL are scarce regarding the effects of infection on the IT and GM. OBJECTIVES This study aimed to investigate changes observed in the colon of Leishmania infantum-infected hamsters, including alterations in the enteric nervous system (ENS) and GM (specifically, levels of bifidobacteria and lactobacilli). METHODS Male hamsters were inoculated with L. infantum and euthanised at four or eight months post-infection. Intestines were processed for histological analysis and GM analysis. Quantitative polymerase chain reaction (qPCR) was performed to quantify each group of bacteria: Bifidobacterium spp. (Bf) and Lactobacillus spp (LacB). FINDINGS Infected hamsters showed histoarchitectural loss in the colon wall, with increased thickness in the submucosa and the mucosa layer, as well as greater numbers of intraepithelial lymphocytes. Forms suggestive of amastigotes were seen inside mononuclear cells. L. infantum infection induced changes in ENS, as evidenced by increases in the area of colonic enteric ganglia. Despite the absence of changes in the levels of Bf and LacB during the course of infection, the relative abundance of these bacteria was associated with parasite load and histological alterations. MAIN CONCLUSIONS Our results indicate that L. infantum infection leads to important changes in the colon and suggest that bacteria in the GM play a protective role.

Resumo Fundamento: O risco cardiovascular das diversas comunidades indígenas não está bem estabelecido e pode ser influenciado pelo processo de urbanização a que se submetem esses povos. Objetivos: Investigar o perfil da mortalidade cardiovascular (CV) das populações indígenas durante o rápido processo de urbanização altamente influenciado por intervenções governamentais de infraestrutura no Nordeste do Brasil. Métodos: Avaliamos a mortalidade de populações indígenas (≥ 30 anos) do Vale do São Francisco (Bahia e Pernambuco) no período de 2007-2011. Considerou-se mortalidade CV se a causa de morte constasse no grupo de doenças CV do CID-10 ou se tivesse sido registrada como morte súbita. As populações indígenas foram divididas em dois grupos conforme o grau de urbanização baseado em critérios antropológicos: Grupo 1 - menos urbanizadas (Funi-ô, Pankararu, Kiriri e Pankararé); e Grupo 2 - mais urbanizadas (Tuxá, Truká e Tumbalalá). Taxas de mortalidade de cidades altamente urbanizadas (Petrolina e Juazeiro) nas proximidades das áreas indígenas foram também avaliadas. A análise explorou tendências na porcentagem de mortalidade CV para cada população estudada. Adotou-se o valor de p < 0,05 como significância estatística. Resultados: Houve 1.333 mortes indígenas nas tribos da Bahia e de Pernambuco (2007-2011): 281 no Grupo 1 (1,8% da população de 2012) e 73 no Grupo 2 (3,7% da população de 2012), mortalidade CV de 24% e 37%, respectivamente (p = 0,02). Entre 2007 e 2009, houve 133 mortes no Grupo 1 e 44 no Grupo 2, mortalidade CV de 23% e 34%, respectivamente. Entre 2009 e 2010, houve 148 mortes no Grupo 1 e 29 no Grupo 2, mortalidade CV de 25% e 41%, respectivamente. Conclusões: A urbanização parece influenciar os aumentos de mortalidade CV dos povos indígenas vivendo de modo tradicional. Mudanças no estilo de vida e ambientais devidas à urbanização somadas à subótima atenção à saúde podem estar implicadas no aumento do risco CV nos povos indígenas.

Abstract Background: The cardiovascular risk burden among diverse indigenous populations is not totally known and may be influenced by lifestyle changes related to the urbanization process. Objectives: To investigate the cardiovascular (CV) mortality profile of indigenous populations during a rapid urbanization process largely influenced by governmental infrastructure interventions in Northeast Brazil. Methods: We assessed the mortality of indigenous populations (≥ 30 y/o) from 2007 to 2011 in Northeast Brazil (Bahia and Pernambuco states). Cardiovascular mortality was considered if the cause of death was in the ICD-10 CV disease group or if registered as sudden death. The indigenous populations were then divided into two groups according to the degree of urbanization based on anthropological criteria:9,10 Group 1 - less urbanized tribes (Funi-ô, Pankararu, Kiriri, and Pankararé); and Group 2 - more urbanized tribes (Tuxá, Truká, and Tumbalalá). Mortality rates of highly urbanized cities (Petrolina and Juazeiro) in the proximity of indigenous areas were also evaluated. The analysis explored trends in the percentage of CV mortality for each studied population. Statistical significance was established for p value < 0.05. Results: There were 1,333 indigenous deaths in tribes of Bahia and Pernambuco (2007-2011): 281 in Group 1 (1.8% of the 2012 group population) and 73 in Group 2 (3.7% of the 2012 group population), CV mortality of 24% and 37%, respectively (p = 0.02). In 2007-2009, there were 133 deaths in Group 1 and 44 in Group 2, CV mortality of 23% and 34%, respectively. In 2009-2010, there were 148 deaths in Group 1 and 29 in Group 2, CV mortality of 25% and 41%, respectively. Conclusions: Urbanization appears to influence increases in CV mortality of indigenous peoples living in traditional tribes. Lifestyle and environmental changes due to urbanization added to suboptimal health care may increase CV risk in this population.

Resumo Objetivo: Avaliar o papel do raios X de tórax na identificação de casos de pneumonia adquirida na comunidade (PAC) causada por agentes bacterianos. Métodos: A frequência de infecção por Streptococcus pneumoniae, Haemophilus influenzae e Moraxella catarrhalis em crianças com PAC não hospitalizadas foi comparada com a presença de confirmação radiológica da pneumonia (n = 249 crianças com pneumonia radiologicamente confirmada e 366 crianças com raios X de tórax normal). Infecção por S. pneumoniae foi diagnosticada com base na resposta sorológica a pelo menos uma dentre oito proteínas pneumocócicas investigadas (aumento ≥ 2 vezes nos níveis de IgG em relação a Ply, CbpA, PspA1 e 2, PhtD, StkP-C e PcsB-N ou aumento≥ 1,5 vez em relação aPcpA). Infecção por H. influenzae e M. catarrhalis foi definida por aumento ≥ 2 vezes nos níveis de IgG específica a antígenos de cada agente. Resultados: Crianças com pneumonia radiologicamente confirmada apresentaram maior taxa de infecção pelo pneumococo. Além disso, a presença de infecção pneumocócica foi um fator preditor de pneumonia radiologicamente confirmada, o que aumenta sua chance de detecção em 2,8 vezes (IC 95%: 1,8-4,3). O valor preditivo negativo do raios X normal para a infecção por S. pneumoniae foi 86,3% (IC95%: 82,4%-89,7%). Não houve diferença nas frequências de infecção por H. influenzae e M. catarrhalis entre crianças com PAC com ou sem confirmação radiológica. Conclusão: Crianças com diagnóstico clínico de PAC submetidas a um raios X de tórax que apresentam confirmação radiológica têm maior taxa de infecção por S. pneumoniae comparadas com as crianças com raios X normal.

Abstract Objective: Community-acquired pneumonia is an important cause of morbidity in childhood, but the detection of its causative agent remains a diagnostic challenge. The authors aimed to evaluate the role of the chest radiograph to identify cases of community-aquired pneumonia caused by typical bacteria. Methods: The frequency of infection by Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis was compared in non-hospitalized children with clinical diagnosis of community acquired pneumonia aged 2-59 months with or without radiological confirmation (n = 249 and 366, respectively). Infection by S. pneumoniae was diagnosed by the detection of a serological response against at least one of eight pneumococcal proteins (defined as an increase ≥2-fold in the IgG levels against Ply, CbpA, PspA1 and PspA2, PhtD, StkP-C, and PcsB-N, or an increase ≥1.5-fold against PcpA). Infection by H. influenzae and M. catarrhalis was defined as an increase ≥2-fold on the levels of microbe-specific IgG. Results: Children with radiologically confirmed pneumonia had higher rates of infection by S. pneumoniae. The presence of pneumococcal infection increased the odds of having radiologically confirmed pneumonia by 2.8 times (95% CI: 1.8-4.3). The negative predictive value of the normal chest radiograph for infection by S. pneumoniae was 86.3% (95% CI: 82.4-89.7%). There was no difference on the rates of infection by H. influenzae and M. catarrhalis between children with community-acquired pneumonia with and without radiological confirmation. Conclusions: Among children with clinical diagnosis of community-acquired pneumonia submitted to chest radiograph, those with radiologically confirmed pneumonia present a higher rate of infection by S. pneumoniae when compared with those with a normal chest radiograph.

Canine visceral leishmaniasis (CVL) diagnosis is still a challenge in endemic areas with limited diagnostic resources. This study proposes a score with the potential to distinguish positive CVL cases from negative ones. We studied 265 dogs that tested positive for CVL on ELISA and parasitological tests. A score ranging between 0 and 19 was recorded on the basis of clinical signs. Dogs with CVL had an overall higher positivity of the majority of clinical signs than did dogs without CVL or with ehrlichiosis. Clinical signs such as enlarged lymph nodes (83.93%), muzzle/ear lesions (55.36%), nutritional status (51.79%), bristle condition (57.14%), pale mucosal colour (48.21%), onychogryphosis (58.93%), skin lesion (39.28%), bleeding (12.50%), muzzle depigmentation (41.07%), alopecia (39.29%), blepharitis (21.43%), and keratoconjunctivitis (42.86%) were more frequent in dogs with CVL than in dogs with ehrlichiosis or without CVL. Moreover, the clinical score increased according to the positivity of all diagnostic tests (ELISA, p < 0.001; parasite culture, p = 0.0021; and smear, p = 0.0003). Onychogryphosis (long nails) [odds ratio (OR): 3.529; 95% confidence interval (CI): 1.832-6.796; p < 0.001], muzzle depigmentation (OR: 4.651; 95% CI: 2.218-9.750; p < 0.001), and keratoconjunctivitis (OR: 5.400; 95% CI: 2.549-11.441; p < 0.001) were highly associated with CVL. Interestingly, a score cut-off value ≥ 6 had an area under the curve of 0.717 (p < 0.0001), sensitivity of 60.71%, and specificity of 73.64% for CVL diagnosis. The clinical sign-based score for CVL diagnosis suggested herein can help veterinarians reliably identify dogs with CVL in endemic areas with limited diagnostic resources.

Leishmania are protozoan parasites that show remarkable diversity, as revealed by the various clinical forms of leishmaniasis, which can range from mild skin lesions to severe metastatic cutaneous/mucosal lesions. The exact nature and extent of Leishmania phenotypic diversity in establishing infection is not fully understood. In order to try to understand some aspects of this diversity, we subcutaneously infected BALB/c mice with first and second generation subclones of a L. amazonensis strain isolated from a patient (BA125) and examined in vivo lesion growth rate and antimony susceptibility. In vivo fast-, medium- and slow-growing subclones were obtained; moreover, fast-growing subclones could generate slow-growing subclones and inversely, revealing the continuous generation of diversity after passage into mice. No antimony-resistant subclone appeared, probably a rare occurrence. By tagging subclone cells with a L. amazonensis genomic cosmid library, we found that only a very small number of founding cells could produce lesions. Leishmania clones transfected with in vivo selected individual cosmids were also diverse in terms of lesion growth rate, revealing the cosmid-independent intrinsic characteristics of each clone. Our results suggest that only a few of the infecting parasites are able to grow and produce lesions; later, within the cell mixture of each lesion, there coexist several parasite populations with different potentialities to grow lesions during the next infection round. This may reflect a sort of programmed heterogeneity of individual parasites, favoring the survival of some individuals in various environmental conditions.

Localised cutaneous leishmaniasis (LCL) is the most common form of cutaneous leishmaniasis characterised by single or multiple painless chronic ulcers, which commonly presents with secondary bacterial infection. Previous culture-based studies have found staphylococci, streptococci, and opportunistic pathogenic bacteria in LCL lesions, but there have been no comparisons to normal skin. In addition, this approach has strong bias for determining bacterial composition. The present study tested the hypothesis that bacterial communities in LCL lesions differ from those found on healthy skin (HS). Using a high throughput amplicon sequencing approach, which allows for better populational evaluation due to greater depth coverage and the Quantitative Insights Into Microbial Ecology pipeline, we compared the microbiological signature of LCL lesions with that of contralateral HS from the same individuals.Streptococcus, Staphylococcus,Fusobacterium and other strict or facultative anaerobic bacteria composed the LCL microbiome. Aerobic and facultative anaerobic bacteria found in HS, including environmental bacteria, were significantly decreased in LCL lesions (p < 0.01). This paper presents the first comprehensive microbiome identification from LCL lesions with next generation sequence methodology and shows a marked reduction of bacterial diversity in the lesions.

Introduction: This work was carried out on the purpose of identifying the species of phlebotomine sandflies in the municipality of Monte Negro, state of Rondonia, Brazil, that may have been transmitting the American cutaneous leishmaniasis (ACL), and concisely describe epidemiological aspects of disease. METHODS: The epidemiologic and socioeconomical indicators were obtained from government institutions and the local Municipal Secretary of Health. Phlebotomine sandflies were captured using CDC light traps between July 2006 to July 2008. The total of 1,240 of female sandflies were examined by PCR method directed to k-DNA. RESULTS: There has been a significant decrease in the incidence of ACL of about 50% over the last ten years in the municipality. A total of 1,935 specimens of 53 sandfly species were captured, three of the genus Brumptomyia genus and 50 of the genus Lutzomyia. The predominant species was Lutzomyia acanthopharynx, Lutzomyia whitmani, Lutzomyia geniculata and Lutzomyia davisi. None were positive for Leishmania sp. CONCLUSIONS: Four sandflies species were found in the State of Rondonia for the first time: Brumptomyia brumpti, Lutzomyia tarapacaensis, Lutzomyia melloi and Lutzomyia lenti. The presence of Lutzomyia longipalpis, was also captured. Socioeconomical improvement of Brazilian economy and the increase of environmental surveillance in the last 15 years collaborated in the decrease of people exposed to vectors, reducing the incidence of ACL.

OBJETIVO: Avaliar o processo de implantação de um sistema de qualidade em um laboratório de pesquisa básica, avaliando a viabilidade e os impactos dessa melhoria. MÉTODOS: Tratou-se de um estudo qualitativo prospectivo. Utilizou-se a norma NIT DICLA 035 - Princípios das Boas Práticas de Laboratório (BPL) e documentos da Organisation for Economic Co-operation and Development para complementar o planejamento e a implantação de um Sistema de Gestão da Qualidade, em um laboratório de pesquisa básica. Em paralelo, utilizou-se a ferramenta PDCA para definir os objetivos de cada etapa de implantação do sistema de qualidade. RESULTADOS: Este trabalho possibilitou ao laboratório atender requisitos solicitados pela norma NT DICLA 035 e implementá-los durante a execução de um projeto, dentre eles a elaboração de documentos, bem como estabelecer rotinas importantes para o andamento do mesmo, como a identificação de não conformidades, rastreabilidade de dados e calibração de equipamentos. CONCLUSÃO: A implantação do Sistema da Qualidade BPL, nesse cenário, é viável, gerando impactos positivos na rotina do laboratório.

OBJECTIVE: To evaluate the process of implementing a quality management system in a basic research laboratory of a public institution, particularly considering the feasibility and impacts of this improvement. METHODS: This was a prospective and qualitative study. We employed the norm "NIT DICLA 035 - Princípios das Boas Práticas de Laboratório (BPL)" and auxiliary documents of Organisation for Economic Co-operation and Development to complement the planning and implementation of a Quality System, in a basic research laboratory. In parallel, we used the PDCA tool to define the goals of each phase of the implementation process. RESULTS: This study enabled the laboratory to comply with the NIT DICLA 035 norm and to implement this norm during execution of a research study. Accordingly, documents were prepared and routines were established such as the registration of non-conformities, traceability of research data and equipment calibration. CONCLUSION: The implementation of a quality system, the setting of a laboratory focused on basic research is feasible once certain structural changes are made. Importantly, impacts were noticed during the process, which could be related to several improvements in the laboratory routine.

It is not well established whether cytokine production differs in response to different clinical forms of visceral leishmaniasis (VL). In this work, we performed a cross-sectional study to investigate the plasma levels of cytokines [interferon (IFN)-γ, tumour necrosis factor (TNF)-α, interleukin (IL)-2, IL-4, IL-10 and IL-12] involved in the pathogenesis of VL in 80 subjects from VL endemic areas, including subjects with active VL, subjects with asymptomatic infection, subjects with cured VL and uninfected controls. The patients were recruited by sampling from a referral hospital and by random selection from a population-based cohort study. The results showed significant differences in the plasma concentration of all cytokines between the groups (p < 0.05). Patients with the active disease had higher plasma levels of IL-10, IL-4, INF-γ and TNF-α relative to the other groups and they produced more IL-12 than asymptomatic and cured subjects. Only the IL-2 concentration was higher in the asymptomatic and cured subjects relative to the patients with active disease (p < 0.05). Our results suggest that these cytokines can be used as markers in epidemiological studies conducted in endemic areas to distinguish between different clinical forms of VL. However, their usefulness should be confirmed in investigations conducted in other endemic areas.

OBJETIVO: Estimar a frequência de história pregressa de chiado, descrevendo as características clínicas e formas de tratamento utilizadas. MÉTODOS: Coorte retrospectiva incluindo lactentes (6-23 meses de vida) com sintomas de infecção de vias aéreas superiores e relato de episódio prévio de chiado. Os dados foram registrados em questionário anteriormente validado. RESULTADOS: Dos 451 avaliados, 164 (36,4%; IC95% = 31,9-41,0) apresentaram história pregressa de chiado, 148 (32,8%; IC95% = 28,5-37,4) no primeiro ano de vida. A média de idade no primeiro episódio de chiado foi de 5,3±3,9 meses. Para quem começou a chiar no primeiro ano de vida, 38,5% referiram entre três e seis episódios e 14,2% > seis episódios. A média da idade no primeiro episódio foi menor para os que apresentaram > três episódios em comparação aos que apresentaram até dois episódios (3,2±2,7 versus 5,7±2,5 meses, p < 0,001). CONCLUSÃO: Um terço dos lactentes apresentou chiado no primeiro ano de vida. Quanto mais cedo ocorre o primeiro episódio, mais frequente é a recorrência do chiado.

OBJECTIVE: To estimate the frequency and describe the clinical characteristics and respective treatments of previous history of wheezing. METHODS: Infants aged 6-23 months with upper respiratory tract complaints and reporting previous wheezing were followed-up retrospectively. Data were registered on a validated standardized form. RESULTS: Out of 451 infants, 164 (36.4%; 95%CI: 31.9-41.0) had a report of prior history of wheezing, 148 (32.8%; 95%CI: 28.5-37.4) during the first year of life. The mean age at the first episode of wheezing was 5.3±3.9 months. Among those who had had their first episode before 12 months of age, 38.5% reported 3 to 6 episodes and 14.2% > 6 episodes. Mean age at first episode was lower for those with > 3 episodes in comparison with those with < 2 episodes (3.2±2.7 vs. 5.7±2.5 months, p < 0.001). CONCLUSION: One third of the infants reported wheezing during the first year of life. The earlier the first episode occurs, the more frequently wheezing recurs.

INTRODUÇÃO: A infecção por Leishmania chagasi é a apresentação clínica mais comum de laishmaniose visceral em áreas endêmicas. O município de Raposa é área endêmica no Estado do Maranhão, tendo registrado casos da doença. Por isso, realizou-se um estudo transversal, com o objetivo de estudar os fatores de risco para infecção por L. chagasi detectada pelo teste intradérmico de Montenegro. MÉTODOS: O estudo envolveu 96% dos moradores das localidades de Maresia, Pantoja e Marisol do município da Raposa, totalizando 1.359 indivíduos. O levantamento dos dados foi realizado utilizando um questionário. Para verificar a associação entre as variáveis estudadas e a infecção por L. chagasi, foram utilizados os modelos de regressão logística uni e multivariada. RESULTADOS: Na análise não ajustada, as variáveis associadas à infecção foram: cobertura da casa de palha, paredes de taipa, piso de chão batido, a presença de flebotomíneos dentro ou fora do domicílio e o local do banho fora de casa. Na análise ajustada, a presença de flebotomíneos dentro ou fora do domicílio foi considerada fator de risco e a idade menor que 10 anos revelou-se como fator de proteção para a infecção assintomática. CONCLUSÕES: Evidenciou-se também, o quanto a precariedade das condições de vida da população contribui para o fortalecimento da cadeia epidemiológica da doença.

INTRODUCTION: Infection with Leishmania chagasi is the most common clinical presentation for visceral leishmaniaisis in endemic areas. The municipality of Raposa is an endemic area in State of Maranhão, Brazil, and have had registration cases of visceral leishmaniasis disease. For this reason, a cross- sectional study was conducted to evaluate the risk factors for infection with L. chagasi detected by Montenegro skin test. METHODS: The sample comprised 96% of the inhabitants of the villages of Maresia, Pantoja, and Marisol located in the municipality of Raposa, corresponding to 1,359 subjects. Data were collected using a questionnaire. Univariate and multivariate logistic regression models were applied to evaluate the association between the variables studied and infection of L. chagasi. RESULTS: The variables associated with infection upon nonadjusted analysis were a straw roof, mud walls, floors of beaten earth, presence of sand flies inside or outside of the dwelling, and bathing outdoors. Adjusted analysis showed that the presence of sand flies inside/outside the dwelling was a risk factor, and age younger than 10 years was a protective factor against asymptomatic infection. CONCLUSIONS: The results highlight the extent to which precarious living conditions of the population strengthen the epidemiological chain of visceral leishmaniasis.

Leishmania infection in humans, dogs and sandflies was examined in the endemic visceral leishmaniasis (VL) municipality of Raposa, state of Maranhão, Brazil. In this study, we examined Leishmania chagasi infection in the blood serum of both humans and Canis familiaris and the natural Leishmania sp. infection rate in the sandfly vector, Lutzomyia longipalpis. Enzyme-linked immunosorbent assay, indirect immunofluorescence reaction and polymerase chain reaction were performed to detect Leishmania infections in humans, dogs and sandflies, respectively. Overall, 186 out of 986 studied human beings were infected with L. chagasi parasites, representing an infection prevalence of 18.9%. An even higher infection rate was detected in dogs, where 66 (47.8%) out of 138 were infected. Among all Lu. longipalpis captured (n = 1,881), only 26.7% were females. The Leishmania infection frequency for the vector Lu. longipalpis was 1.56%. Remarkably, all infected sandflies were found in the peridomiciliary area. Furthermore, a high incidence of asymptomatic forms of VL in the human and canine populations was observed. The results of this study suggest autochthonous transmission of L. chagasi in this endemic area for visceral leishmaniasis because infection by Leishmania sp. was identified in all important elements of the transmission chain.

Leishmania amazonensis causes different diseases depending on the host and parasitic virulence factors. In this study, CBA mice were infected with L. amazonensis isolates from patients with localized (Ba125), diffuse cutaneous (Ba276) or visceral leishmaniasis (Ba109). Mice infected with Ba125 and Ba276 progressed rapidly and lesions displayed an infiltrate rich in parasitized macrophages and were necrotic and ulcerated. Ba109 induced smaller lesions and a mixed inflammatory infiltrate without necrosis or ulceration. Ba109 induced an insidious disease with lower parasite load in CBA mice, similar to human disease. Levels of IFN-γ, IL-4 and IL-10 did not differ among the groups. Because all groups were unable to control the infection, expression of IL-4 associated with low production of IFN-γ in the early phase of infection may account for susceptibility, but others factors may contribute to the differences observed in inflammatory responses and infection progression. Evaluation of some parasitic virulence factors revealed that Ba276 exhibits higher ecto-ADPase and 5'-nucleotidase activities compared to the Ba109 and Ba125 strains. Both Ba276 and Ba125 had higher arginase activity in comparison to Ba109. Finally, these data suggest that the differences in enzyme activities among parasites can account for differences in host inflammatory responses and infection progression.

O objetivo deste estudo foi investigar a infecção natural por Leishmania chagasi em flebotomíneos capturados em focos de leishmanioses visceral (LV) na ilha de São Luís, Maranhão, Brasil. Análise molecular por reação em cadeia da polimerase (PCR) foi aplicada para determinar a taxa de infecção natural de Lutzomyia longipalpis por L. chagasi em áreas de ocupação humana antiga e recente, na ilha de São Luís. Valendo-se de uma amostra de 800 fêmeas coletadas no período de março a agosto de 2005, foi possível determinar taxas de infecção natural equivalentes a 1,25% em uma localidade de colonização antiga e 0,25% em duas localidades de colonização recente. A infecção foi detectada nas duas localidades independentemente do número de casos humanos de LV notificados, o que demonstra que outros elementos que modulam a infecção no meio natural precisam ser investigados. Os resultados obtidos confirmam a PCR como técnica específica e importante ferramenta para as ações em vigilância epidemiológica.

The main purpose of this study was to investigate natural infection by Leishmania chagasi in female sand flies in a visceral leishmaniasis (VL) focus on São Luís Island, Maranhão State, Brazil. Molecular analysis by polymerase chain reaction (PCR) was applied to determine the rate of natural infection of Lutzomyia longipalpis by L. chagasi in areas of old and recent human settlement on São Luís Island. Based on a sample of 800 female specimens captured from March to August 2005, the natural infection rate was 1.25% in an area of old settlement and 0.25% in two recently settled areas. Infection of L. longipalpis was detected in both areas, regardless of the number of reported human VL cases, indicating that other factors modulating infection in the wild need to be investigated. The results confirm PCR as a specific technique and an important tool for epidemiological surveillance.