Immunodominant antigens of Leishmania chagasi associated with protection against human visceral leishmaniasis.

BACKGROUND: Protection and recovery from visceral leishmaniasis (VL) have been associated with cell-mediated immune (CMI) responses, whereas no protective role has been attributed to humoral responses against specific parasitic antigens. In this report, we compared carefully selected groups of individuals with distinct responses to Leishmania chagasi to explore antigen-recognizing IgG present in resistant individuals. METHODOLOGY AND PRINCIPAL FINDINGS: VL patients with negative delayed-type hypersensitivity (DTH) were classified into the susceptible group. Individuals who had recovered from VL and converted to a DTH+ response, as well as asymptomatic infected individuals (DTH+), were categorized into the resistant group. Sera from these groups were used to detect antigens from L. chagasi by conventional and 2D Western blot assays. Despite an overall reduction in the reactivity of several proteins after DTH conversion, a specific group of proteins (approximately 110-130 kDa) consistently reacted with sera from DTH converters. Other antigens that specifically reacted with sera from DTH+ individuals were isolated and tandem mass spectrometry followed by database query with the protein search engine MASCO were used to identify antigens. The serological properties of recombinant version of the selected antigens were tested by ELISA. Sera from asymptomatic infected people (DTH+) reacted more strongly with a mixture of selected recombinant antigens than with total soluble Leishmania antigen (SLA), with less cross-reactivity against Chagas disease patients' sera. SIGNIFICANCE: Our results are the first evidence of leishmania proteins that are specifically recognized by sera from individuals who are putatively resistant to VL. In addition, these data highlight the possibility of using specific proteins in serological tests for the identification of asymptomatic infected individuals.

Epidemiological study of the association between anti-Lutzomyia longipalpis saliva antibodies and development of delayed-type hypersensitivity to Leishmania antigen.

Recent reports from animal models and from cross-sectional studies have suggested that host responses to anti-Lutzomyia longipalpis saliva antibodies may be related to delayed-type hypersensitivity to Leishmania antigen. In a prospective cohort study, we evaluated 1,080 children from two endemic areas for visceral leishmaniasis (VL) by means of Kaplan-Meier analysis. The incidence rate of delayed-type hypersensitivity to Leishmania antigen, measured at the 24th follow-up month, was higher among those reactive to Lu. longipalpis saliva antibodies at the beginning of the study (0.0217 cases per person-month) than among those previously negative (0.0131 cases per person-month) (P value for the log-rank test = 0.0006). It seems that mounting an anti-saliva immune response helps the development of a cell-mediated anti-Leishmania response.

Are there differences in clinical and laboratory parameters between children and adults with American visceral leishmaniasis?

A prospective study on 23 patients with American visceral leishmaniasis (VL), comparing clinical and laboratory parameters of 14 children (mean age of 3.85+/-3.39 years) to nine adults (27.4+/-10.90 years) was performed in São Luís, Maranhão, Brazil, between August 2000 and July 2002. Data were collected at entrance (day 0), end of treatment, as well as 120 and 210 days after treatment using a protocol chart containing patient identification, clinical and laboratory data. N-Methylglucamine antimonate administered at the dose of 20mg/Sb5+/kg/day for 20-30 days was successfully used in all patients. Patients were followed for 1 year after treatment, and no relapses were observed. A prolonged duration of the disease, lymphadenopathy and bleeding predominated in adult patients, while hepatomegaly and skin-mucosal pallor were more frequent in children. Disease was longer and more severe in adults than in children. Although both groups exhibited a trend toward normalization of hematological and biochemical parameters, more children returned sooner to normal values than adults. Difference in clinical or laboratory parameters between children and adults did not indicate the need for different clinical or therapeutic approaches.

Visceral leishmaniasis in pregnancy: a case report.

Visceral leishmaniasis (VL) is endemic in the island of São Luis, State of Maranhão, Brazil. Despite an increase in the number of VL cases, the frequency of the disease is low among pregnant women. We present here the case of a pregnant woman followed up by our group, who was treated with amphotericin B with excellent outcome.

Infecçäo por Leishmania (Leishmania) chagasi em crianças de uma área endêmica de leishmaniose visceral americana na Ilha de Säo Luís-MA, Brasil / Leishmania (Leishmania) chagasi infection on childhood from endemic area of visceral leishmaniasis in the Säo Luis-MA, island

Realizou-se estudo prospectivo com 648 crianças de zero a cinco anos no município da Raposa-MA, de julho/97 a junho/98, com o objetivo de avaliar as características da infecção por L.(L.)chagasi e verificar se existe associação entre desnutrição e infecção assintomática. Utilizou-se questionário com dados socioeconômicos, ambientais e hábitos de vida; realizou-se Intradermorreação de Montenegro(IDRM) com antígeno de L. amazonensis e Enzyme Linked Immunosorbant Assay(ELISA) para detectar infecção, e exame antropométrico. A prevalência inicial, final e incidência da infecção foram 18,6 por cento, 20,6 por cento e 10,8 por cento pelo IDRM, e 13,5 por cento, 34,4 por cento e 28 por cento pelo ELISA, respectivamente. A prevalência da desnutrição crônica (altura/idade) foi 26 por cento. Não houve associação estatisticamente significante entre desnutrição e infecção assintomática por L. (L.) chagasi. A forma assintomática da doença está presente nas áreas estudadas, necessitando de medidas de controle mais efetivas