Identifying thresholds for classifying moderate-to-heavy soil-transmitted helminth intensity infections for FECPAKG2, McMaster, Mini-FLOTAC and qPCR.

The World Health Organization (WHO) has defined moderate-to-heavy intensity (M&HI) infections with soil-transmitted helminths (Ascaris lumbricoides, Trichuris trichiura and the two hookworms, Ancylostoma duodenale and Necator americanus) based on specific values of eggs per gram of stool, as measured by the Kato-Katz method. There are a variety of novel microscopy and DNA-based methods but it remains unclear whether applying current WHO thresholds on to these methods allows for a reliable classification of M&HI infections. We evaluated both WHO and method-specific thresholds for classifying the M&HI infections for novel microscopic (FECPAKG2, McMaster and Mini-FLOTAC) and DNA-based (qPCR) diagnostic methods. For this, we determined method-specific thresholds that best classified M&HI infections (defined by Kato-Katz and WHO thresholds; reference method) in two multi-country drug efficacy studies. Subsequently, we verified whether applying these method-specific thresholds improved the agreement in classifying M&HI infections compared to the reference method. When we applied the WHO thresholds, the new microscopic methods mainly misclassified M&HI as low intensity, and to a lesser extent low intensity infection as M&HI. For FECPAKG2, applying the method-specific thresholds significantly improved the agreement for Ascaris (moderate → substantial), Trichuris and hookworms (fair → moderate). For Mini-FLOTAC, a significantly improved agreement was observed for hookworms only (fair → moderate). For the other STHs, the agreement was almost perfect and remained unchanged. For McMaster, the method-specific thresholds revealed a fair to a substantial agreement but did not significantly improve the agreement. For qPCR, the method-specific thresholds based on genome equivalents per ml of DNA moderately agreed with the reference method for hookworm and Trichuris infections. For Ascaris, there was a substantial agreement. We defined method-specific thresholds that improved the classification of M&HI infections. Validation studies are required before they can be recommended for general use in assessing M&HI infections in programmatic settings.

IgE antibodies from schistosomiasis patients to recognize epitopes in potato apyrase.

INTRODUCTION: High percentages of structural identity and cross-immunoreactivity have been reported between potato apyrase and Schistosoma mansoni ATP diphosphohydrolase (SmATPDases) isoforms, showing the existence of particular epitopes shared between these proteins. METHODS: Potato apyrase was employed using ELISA, western blot, and mouse immunization methods to verify IgE reactivity. RESULTS: Most of the schistosomiasis patient's (75%) serum was seropositive for potato apyrase and this protein was recognized using western blotting, suggesting that parasite and plant proteins share IgE-binding epitopes. C57BL/6 mice immunized with potato apyrase showed increased IgE antibody production. CONCLUSIONS: Potato apyrase and SmATPDases have IgE-binding epitopes.

IgE antibodies from schistosomiasis patients to recognize epitopes in potato apyrase

Abstract INTRODUCTION: High percentages of structural identity and cross-immunoreactivity have been reported between potato apyrase and Schistosoma mansoni ATP diphosphohydrolase (SmATPDases) isoforms, showing the existence of particular epitopes shared between these proteins. METHODS: Potato apyrase was employed using ELISA, western blot, and mouse immunization methods to verify IgE reactivity. RESULTS: Most of the schistosomiasis patient's (75%) serum was seropositive for potato apyrase and this protein was recognized using western blotting, suggesting that parasite and plant proteins share IgE-binding epitopes. C57BL/6 mice immunized with potato apyrase showed increased IgE antibody production. CONCLUSIONS: Potato apyrase and SmATPDases have IgE-binding epitopes.

HIV aspartyl protease inhibitors modify the percentage of activated leukocytes, as well as serum levels of IL-17A and NO during experimental leishmaniasis.

HIV aspartyl protease inhibitors are able to modulate multiple defense mechanisms. However, their influence on the immune response against Leishmania has rarely been investigated. The aim of our study was to investigate whether in vivo treatment with HIV aspartyl protease inhibitors is able to modulate the immune response during Leishmania infection. Using Leishmania (L.) amazonensis-infected mice, we analyzed the disease evolution and parasite load, immunophenotypic profiles of splenic T and B lymphocytes, numbers of lymphoid aggregates in the spleen, percentages of circulating atypical lymphocytes and reactive monocytes, and serum levels of cytokines and nitric oxide (NO) after 30 days of oral treatment with lopinavir/ritonavir (LPV/RTV) or atazanavir (ATV). We observed that LPV/RTV and ATV did not modify the disease evolution or parasite load. However, the antiretroviral treatment induced an increase in activated lymphocytes in the spleen and blood, as well as a decrease in CD69 expression in T and B lymphocytes in the spleen. The treatment also resulted in an increase in activated monocytes in the blood. In addition, antiretrovirals decreased levels of IL-17A and increased levels of NO in sera from Leishmania-infected mice. Thus, our results demonstrate for the first time that in vivo treatment with HIV aspartyl protease inhibitors modifies innate and adaptative immune responses during Leishmania infection and suggest that these drugs could change the clinical course of leishmaniasis in HIV infected-individuals.

Indicadores da hanseníase no Estado de Minas Gerais e sua relação com o índice de desenvolvimento humano municipal e a cobertura da estratégia da saúde da família / Indicators of leprosy in the state of Minas Gerais and its relationship with the municipal human development index and the coverage of the family health strategy / Indicadores de lepra en el estado de minas gerais y su relación con el índice de desarrollo humano municipal y la cobertura de la estrategia salud de la familia

O objetivo deste estudo foi analisar a relação entre os indicadores epidemiológicos da hanseníase, a cobertura da Estratégia da Saúde da Família (ESF) e o Índice de Desenvolvimento Humano Municipal (IDHM) em Minas Gerais – Brasil, no período de 1998 a 2013. Trata-se de um estudo ecológico. A forma de mensurar as condições de vida foi a partir do IDHM. Foram realizadas duas análises: uma considerando a média de cada indicador no período de 1998 a 2005, e outra de 2006 a 2013. Foi feita análise descritiva da situação epidemiológica da hanseníase, da cobertura da ESF e do IDHM em Minas Gerais. Em seguida, foi estabelecida uma relação geral entre as taxas de detecções, em menores de 15 anos e com grau 2 de incapacidade e a cobertura da ESF e o IDHM, utilizando os testes de Poisson com inflação de zeros e de Deviance. As análises foram realizadas no programa estatístico SPSS versão 19.0 e Stata versão 10.0. Os resultados sugerem redução da endemia no estado, identificado pela queda dos indicadores da doença. O aumento da cobertura da ESF contribuiu para o aumento da detecção de casos da doença, redução de casos em menores de 15 anos e com grau 2 de incapacidade. Além disso, o aumento do IDHM contribuiu para a redução de casos da doença e de incapacidade grau 2. Apesar das políticas de melhoria do acesso aos serviços de saúde e das condições de vida da população, observa-se a persistência de municípios hiperendêmicos no estado.

The objective of this study was to analyze the relationship between the epidemiological indicators of leprosy, the coverage of the Family Health Strategy(ESF) and the Municipal Human Development Index (IDHM) in Minas Gerais – Brasil, from 1998 to 2013. It is an ecological study. The way to measureliving conditions was through the IDHM. Two analysis were carried out: one considering the average of each indicator in the period from 1998 to 2005,and another from 2006 to 2013. A descriptive analysis was made of the epidemiological situation of leprosy, the coverage of the ESF and the IDHM inMinas Gerais. Next, a relationship was established between the general detection rates, in children under 15 years old and with degree 2 of disability;with the coverage of the ESF and the IDHM, using Poisson tests with zero inflation and Deviance. The analysis was performed in the statistical programSPSS version 19.0 and Stata version 10.0. The results suggest a reduction of the endemic disease in the state, identified by the decrease in the disease indicators. Increased ESF coverage has contributed to the increased detection of cases of the disease, reduction of cases in children under 15 years oldand grade 2 disability. The increase in the IDHM has contributed to the reduction of cases of the disease and disability of grade 2. Despite policies toimprove access to health services and the living conditions of the population, we observe the persistence of hyperendemic municipalities in the state.

El objetivo de este estudio fue analizar la relación entre los indicadores epidemiológicos de lepra, la cobertura de la Estrategia Salud de la Familia(ESF) y el Índice de Desarrollo Humano Municipal (IDHM) en Minas Gerais – Brasil, de 1998 a 2013. Se trata de un estudio ecológico. Las condicionesde vida se midieron a través del IDHM. Se realizaron dos análisis: uno basado en el promedio de cada indicador entre 1998 y 2005 y otro entre 2006 y2013. Se realizó el análisis descriptivo de la situación epidemiológica de lepra, de la cobertura de la ESF y del IDHM de Minas Gerais. A continuación, seestableció una relación entre las tasas de detecciones en menores de 15 años y con discapacidad grado 2 y la cobertura de la ESF y el IDHM utilizandolas pruebas de Poisson con inflación de ceros y de deviance. Los análisis se realizaron en el programa estadístico SPSS versión 19.0 y Stata versión10.0. La caída de los indicadores de enfermedad en los resultados señala que reducción de la enfermedad endémica en Minas Gerais. El aumento dela cobertura de la ESF contribuyó al aumento de detección de casos y a la reducción de casos en niños menores de 15 años y discapacidad grado 2.Además, el aumento del IDHM contribuyó a la reducción de casos de la enfermedad y de discapacidad grado 2. Se observa que, a pesar de las políticasde mejora en el acceso a los servicios de salud y en las condiciones de vida de la población, aún persisten municipios hiperendémicos en el estado.

The Human Hookworm Vaccine.

Hookworm infection is one of the world's most common neglected tropical diseases and a leading cause of iron deficiency anemia in low- and middle-income countries. A Human Hookworm Vaccine is currently being developed by the Sabin Vaccine Institute and is in phase 1 clinical testing. The candidate vaccine is comprised of two recombinant antigens known as Na-GST-1 and Na-APR-1, each of which is an important parasite enzyme required for hookworms to successfully utilize host blood as a source of energy. The recombinant proteins are formulated on Alhydrogel(®) and are being tested in combination with a synthetic Toll-like receptor 4 agonist. The aim of the vaccine is to induce anti-enzyme antibodies that will reduce both host blood loss and the number of hookworms attached to the gut. Transfer of the manufacturing technology to the Oswaldo Cruz Foundation (FIOCRUZ)/Bio-Manguinhos (a Brazilian public sector developing country vaccine manufacturer) is planned, with a clinical development plan that could lead to registration of the vaccine in Brazil. The vaccine would also need to be introduced in the poorest regions of Africa and Asia, where hookworm infection is highly endemic. Ultimately, the vaccine could become an essential tool for achieving hookworm control and elimination, a key target in the 2012 London Declaration on Neglected Tropical Diseases.

Rural electrification in Brazil and implications for schistosomiasis transmission: a preliminary study in a rural community in Minas Gerais State, Brazil.

OBJECTIVES: To evaluate the potential transmission of Schistosoma mansoni through well water pumped into households in a rural Brazilian community within the context of Brazil's rural electrification program Luz Para Todos (Light for All). METHODS: All households were interviewed about their water facilities and domestic water use, all household members were examined for S. mansoni infections and positives treated, and malacological and water contact studies were performed between 2001 and 2009. RESULTS: Thirty-one of the 142 households in the Virgem das Graças study area owned wells with electric pumps in 2009, vs. no wells in 2001, and the number of water storage tanks increased from 85 to 131. The potential for schistosomiasis transmission through piped well water was indicated by the recovery of Biomphalaria gabrata, including S. mansoni-infected snails, from wells, the presence of Biomphalaria in tanks and the ability of S. mansoni cercariae to remain infective for considerable distances in flowing water. However, access to well water was not associated with higher S. mansoni infection rates. CONCLUSIONS: Our results indicate that further studies are needed to determine the infectivity of well water and its impact on schistosomiasis transmission.

Enteroglial cells act as antigen-presenting cells in chagasic megacolon.

Chagas disease is one of the most serious parasitic diseases of Latin America, with a social and economic impact far outweighing the combined effects of other parasitic diseases such as malaria, leishmaniasis, and schistosomiasis. In the chronic phase of this disease, the destruction of enteric nervous system components leads to megacolon development. Besides neurons, the enteric nervous system is constituted by enteric glial cells, representing an extensive but relatively poorly described population within the gastrointestinal tract. Several lines of evidence suggest that enteric glial cells represent an equivalent of central nervous system astrocytes. Previous data suggest that enteric glia and neurons are active in the enteric nervous system during intestinal inflammatory and immune responses. To evaluate whether these cells act as antigen-presenting cells, we investigated the expression of molecules responsible for activation of T cells, such as HLA-DR complex class II and costimulatory molecules (CD80 and CD86), by neurons and enteric glial cells. Our results indicate that only enteric glial cells of chagasic patients with megacolon express HLA-DR complex class II and costimulatory molecules, and hence they present the attributes necessary to act as antigen-presenting cells.

Evidence of long term benefit of morbidity reduction due to praziquantel treatment against schistosoma mansoni in Kigungu fishing village in Entebbe, Uganda

Praziquantel (PZQ) is efficacious against Schistosoma mansoni. This was prospective cohort study. This study was carried out at Kigungu fishing village, Entebbe, Uganda. The goal of the study was to establish cost effective regiment for mass drug administration (MDA) of Praziquentel in the morbidity reduction of S.mansoni infection. In January 2004, nine hundred and forty five (945) participants were registered in this study. Our analysis was based on examining microscopically three slides prepared from each of 945 stool specimens delivered by each of the participant using modified Kato/Katz method. These included male and female, children and adults living in Kigungu fishing village in Entebbe Uganda. In total 901, cohorts were re-examined for infections clearance six months later in July 2004 and 18 months later in June 2005, 625 cohorts were again re-evaluated for S.mansoni infections after the baseline study. At baseline, (448) of 945 (47.5%) cohorts were S. mansoni positive. All these participants were treatment with a single oral dose of praziquantel at 40mg/kg. At the same time, 495 (52.5%) were S. mansoni negative. Of the 625 (66.3%) cohorts who came back for final review, 80 (12.8%) were still positive for S. mansoni while 210 (33.6%) remained negative after the base line treatment with praziquantel. On the other hand 103 (16.3%) of cohorts who were initially negative at the base line became S.mansoni positive after 18 months and 213(34.1%) remained negative for S.mansoni. The force of re-infection after six months was significant {(P=0.0001),(OR 0.47) CI at 95% (0.31-0.71)}. Nevertheless the force of reinfection was not significant after 18 months {(P=0.766), (OR 0.95) CI at 95% (0.68-1.34)}.The geometric mean eggs excretion of the 80 cohorts who were S.mansoni positive at 18 months was 151.967.This did not reach the geometric mean egg excreted by the same cohorts at baseline which was 285.05. The egg excretion was reduced by 46.8%. Similarly there was marked decrease in clinical symptoms amongst the cohorts. Our study suggests evidence of long-term benefit of praziquantel in Kigungu and that a yearly administration of praziquantel to the community could be a regiment for mass drug administration (MAD) for this community to control schistosomiasis morbidity

Characterization of enteroglial cells and denervation process in chagasic patients with and without megaesophagus.

Chagas disease is caused by infestation with the parasite Trypanosoma cruzi, and some patients who are serologically positive develop chronic megaesophagus, whereas others are symptom-free. Gastrointestinal form of Chagas disease involves an inflammatory invasion of the enteric plexuses and degeneration of enteric neurons and previous works related that enteroglial cells would be involved in enteric inflammatory responses. Because of this, the aims of this study were to determine the relation of enteroglial cells with the denervation process in chagasic patients with and without megaesophagus and seronegative individuals. Our results indicated that the innervation of the esophageal muscle was substantially reduced in patients with megaesophagus, but asymptomatic seropositive subjects were not different to seronegative controls. Besides, patients with megaesophagus had significant decreased of enteroglial cells labeled with S-100 and glial fibrillary acidic protein, whereas patients without megaesophagus presented an increased of both labels. We believe that enteroglial cells would operate a mechanism of defense in the enteric nervous system against the Trypanosoma cruzi infection, which could prevent the organ denervation and preserve the esophagus function.

Alterations in phenotypic profiles of peripheral blood cells from patients with human American cutaneous leishmaniasis following treatment with an antimonial drug and a vaccine.

The susceptibility or resistance of a vertebrate host to leishmaniasis is related to the species of Leishmania and to the host immune response of the host. In the present study, the phenotypic profiles of the peripheral blood cells of patients with American cutaneous leishmaniasis (ACL) were evaluated before and after receiving three different therapeutic regimens. The study population comprised 24 patients, living in an ACL-endemic area of Caratinga (MG, Brazil), who had been diagnosed as ACL-positive on the basis of characteristic lesions, the Montenegro skin reactivity test, and/or positive parasitology. Subjects were divided into three groups and received treatment regimens based on (i) the pentavalent antimonial (SbV) N-methyl meglumine antimoniate (Glucantime), (ii) the vaccine Leishvacin, or (iii) SbV in association with the vaccine. Comparative analyses of peripheral mononuclear cells prior to and after treatment revealed that the therapeutic regimens induced no significant differences in the percentages of CD3+ and CD4+ T lymphocytes, CD19+ B lymphocytes, or CD16+ and CD56+ natural killer cells. Additionally, the CD4/CD8 and CD3/CD19 ratios remained unaltered by any of the treatments applied. Most previous studies in the field have focused on the analysis of peripheral blood from ACL patients following in vitro stimulation with either Leishmania antigens or mitogens. The ex vivo cellular immune phenotypic profiles determined in the present study, however, revealed that different ACL treatments did not significantly alter either the immune response exhibited by a patient prior to therapy or the expected cure rate.

Neurological disease in HIV-infected patients in the era of highly active antiretroviral treatment: a Brazilian experience.

To study characteristics of neurological disorders in HIV/AIDS patients and their relationship to highly active antiretroviral treatment, a cross-sectional study was conducted in an infectious disease public hospital in Belo Horizonte, Brazil, between February 1999 and March 2000. Of the 417 patients enrolled, neurological disease was observed in 194 (46.5%) and a new AIDS-defining neurological event developed in 23.7% of individuals. Toxoplasmosis (42.3%), cryptococcosis meningitis (12.9%) and tuberculosis (10.8%) were the most common causes of neurological complications. The majority (79.3%) of patients were on highly active antiretroviral treatment and these individuals using HAART showed higher CD4 cell counts (p = 0.014) and presented stable neurological disease (p = 0.0001), although no difference was found with respect to the profile of neurological complications. The neurological diseases continue to be a frequent complication of HIV/AIDS and infections are still its main causes in Brazil, even in the highly active antiretroviral treatment era.

Neurological disease in HIV-infected patients in the era of highly active antiretroviral treatment: a Brazilian experience

Com o objetivo de estudar as doencas neurológicas em pacientes HIV/AIDS e sua relacão com a terapia anti-retroviral altamente ativa, foi realizado estudo transversal em hospital público de doencas infecciosas de Belo Horizonte, Brasil, no período de fevereiro de 1999 a marco de 2000. Doenca neurológica foi observada em 194 (46,5%) dos 417 indivíduos incluídos e um novo episódio de doenca neurológica definidora de AIDS ocorreu em 23,7% pacientes. Toxoplasmose (42,3%), criptococose (12,9%) e tuberculose (10,8%) foram as principais causas de complicacões neurológicas. A maioria dos pacientes estava em uso de terapia anti-retroviral altamente ativa (79,3%) e esses indivíduos apresentaram maiores contagens de linfócitos CD4 (p = 0,014) e maior freqüência de doenca neurológica clinicamente estável, embora não tenha havido diferenca no perfil etiológico das complicacões neurológicas. As doencas neurológicas continuam sendo causas freqüentes de complicacões da infeccão pelo HIV/AIdS no Brasil, e a despeito da terapia anti-retroviral altamente ativa, as infeccões são ainda a principal etiologia das doencas do sistema nervoso.

Combined methods for the study of water contact behavior in a rural schistosomiasis-endemic area in Brazil.

A new combined methodology consisting of direct observation and two types of interviews (internal and external interviews) was evaluated for use in exposure risk assessment in schistosomiasis. Specific objectives were to determine its usefulness in achieving equitable coverage of gendered exposure risk and its efficiency in identifying water contact behavior in a rural area in Brazil with different settlement patterns, land use and domestic water supplies. Of the 2476 water contacts recorded, 1223 (49.4%) were identified by direct observation, 946 (38.2%) by internal interviews and 307 (12.4%) by external interviews. Significantly longer mean durations of contacts were recorded for females and greater mean percentage of body surface exposed for males (P<0.01), reflecting differences in gendered water contact activities. Direct observation identified slightly more male contacts, external interviews significantly more male contacts (P<0.006), and internal interviews moderately more female contacts. The three methods recorded mean numbers of contacts and mean TBM (total body minutes) per person, declining with age. Significant differences were found between the three methods in regard to frequency and/or intensity of washing clothes, fetching water, washing utensils, washing multiple parts of the body, and bathing. The three methods also recorded differentially frequencies and exposure intensities in the three study communities, among different age groups, by gender and for individual study members. These activity-, locality-, age/gender- and person-specific patterns reflect the relative efficiency and complementarity of the three methods in settlements with different land use, access to streams and water supplies.

Distribution and Schistosoma mansoni infection of Biomphalaria glabrata in different habitats in a rural area in the Jequitinhonha Valley, Minas Gerais, Brazil: environmental and epidemiological aspects

This paper examines the distribution and infection of Biomphalaria glabrata with Schistosoma mansoni in all aquatic snail habitats in a rural area in the state of Minas Gerais, Brazil, in relation to physico/biotic and behavioral factors. Snail and environmental surveys were carried out semi-annually between July 2001 and November 2002 at 106 sites. Collected snails were examined in the laboratory for infection. B. glabrata densities were highest in overflow ponds, irrigation ponds, springs, canals and wells, and lowest in fishponds and water tanks. Snail densities were higher during the hot, rainy season except for streams and canals and were statistically associated with the presence of fish, pollution, and vegetation density. Tilapia fish and an unidentified Diptera larva were found to be predators of B. glabrata but ducks were not. Twenty-four of the 25 infected snails were collected in 2001(1.4 percent infection rate) and only one in 2002, after mass chemotherapy. The occurrence of B. glabrata in all 11 snail habitats both at and away from water contact sites studied indicates widespread risk of human infection in the study area. In spite of the strong association between B. glabrata and tilapia in fishponds we do not recommend its use in schistosomiasis control for ecological reasons and its relative inefficiency in streams and dams.

Combined use of enzyme-linked immunosorbent assay and flow cytometry to detect antibodies to Trypanosoma cruzi in domestic canines in Texas.

Canines may be sentinels and/or reservoirs for human Trypanosoma cruzi exposures. This study adapted a method originally designed for human diagnostics to detect serum immunoglobulin G to T. cruzi in canines. The method combined an enzyme-linked immunosorbent assay (ELISA) for screening and flow cytometry detection of anti-live trypomastigote antibodies (ALTA) for confirmation. The assays were optimized by using known positive and negative control canine sera, and cutoff values were established. The ELISA and ALTA assay easily distinguished between reactive (positive controls) and nonreactive (negative controls) sera and were used to test sera collected in a cross-sectional seroprevalence survey of 356 domestic canines from Harris County, Tex., and the surrounding area. Fifty-three (14.9%) of 356 asymptomatic canines in the survey were positive by ELISA, and 5 (1.4%) were confirmed positive with the ALTA assay, with an additional 4 (1.1%) canines classified as "suspect positive." Thus, the overall prevalence of T. cruzi antibodies in this population was 2.6%. This is the first U.S. study to use the combination of ELISA and ALTA to detect serum antibodies to T. cruzi and the first report of the prevalence of T. cruzi infection in domestic canines in the Houston, Tex. (Harris County), region. Our results demonstrate that the combination of ELISA and ALTA has been successfully adapted for use in testing canines for serological evidence of T. cruzi infection. Seroprevalence survey results suggest that T. cruzi antibody-positive domestic canines in the peridomestic setting are present in the Houston, Tex., region and further suggest that T. cruzi is enzootic in the region.

Distribution and Schistosoma mansoni infection of Biomphalaria glabrata in different habitats in a rural area in the Jequitinhonha Valley, Minas Gerais, Brazil: environmental and epidemiological aspects.

This paper examines the distribution and infection of Biomphalaria glabrata with Schistosoma mansoni in all aquatic snail habitats in a rural area in the state of Minas Gerais, Brazil, in relation to physico/biotic and behavioral factors. Snail and environmental surveys were carried out semi-annually between July 2001 and November 2002 at 106 sites. Collected snails were examined in the laboratory for infection. B. glabrata densities were highest in overflow ponds, irrigation ponds, springs, canals and wells, and lowest in fishponds and water tanks. Snail densities were higher during the hot, rainy season except for streams and canals and were statistically associated with the presence of fish, pollution, and vegetation density. Tilapia fish and an unidentified Diptera larva were found to be predators of B. glabrata but ducks were not. Twenty-four of the 25 infected snails were collected in 2001(1.4% infection rate) and only one in 2002, after mass chemotherapy. The occurrence of B. glabrata in all 11 snail habitats both at and away from water contact sites studied indicates widespread risk of human infection in the study area. In spite of the strong association between B. glabrata and tilapia in fishponds we do not recommend its use in schistosomiasis control for ecological reasons and its relative inefficiency in streams and dams.

Double-blind study to evaluate flow cytometry analysis of anti-live trypomastigote antibodies for monitoring treatment efficacy in cases of human Chagas' disease.

The validation of flow cytometry analysis of anti-live trypomastigote antibodies (FC-ALTA) to monitor cure after treatment of Chagas' disease was evaluated with serum samples from treated and nontreated chagasic patients. After optimization of the original technique, toward better sensitivity and applicability to field surveys, we design a double blind study of 94 coded samples classified into the following categories: patients not treated (NT) and patients treated but not cured (TNC), both presenting positive conventional serology and xenodiagnosis; patients treated and cured (TC), showing negative serology and xenodiagnosis; and patients treated under evaluation (TUE), who presented positive or oscillating conventional serology (CSA) but negative xenodiagnosis. Coded samples, diluted 1:256, were assayed by incubation with live cell culture trypomastigotes, which were subsequently stained with fluorescein isothiocyanate-conjugated anti-human immunoglobulin G, with prior fixation and analysis by flow cytometry. The results were expressed as the percentages of positive fluorescent parasites (PPFP) for each individual sample, establishing 20% PPFP as the cutoff between negative and positive results. Our data demonstrated that all NT and TNC presented positive results while all but one TC had a PPFP lower than 20%. Analysis of TUE demonstrated a wide degree of reactivity, with PPFP values that were negative (PPFP 50%). As TUE with negative PPFP presented negative xenodiagnosis and positive or oscillating CSA, they were classified as dissociated according to the criteria of Krettli and Brener (J. Immunol. 128:2009-2012, 1982) and could indeed be considered cured after chemotherapy. This study demonstrates and validates the use of FC-ALTA to easily identify anti-live trypomastigote membrane-bound antibodies, offering another approach for investigating and monitoring the efficacy of specific chemotherapy in cases of human Chagas' disease.

The distribution of Biomphalaria spp. in different habitats in relation to physical, biological, water contact and cognitive factors in a rural area in Minas Gerais, Brazil

A total of 256 sites in 11 habitats were surveyed for Biomphalaria in Melquiades rural area (State of Minas Gerais) in August and November 1999 and in March 2000. Of the 1,780 Biomphalaria collected, 1,721 (96.7 percent) were B. glabrata and 59 (3.3 percent) B. straminea. Snails were found in all habitats except in wells, with the largest mean numbers in tanks, seepage ponds and canals, and the smallest numbers in springs, rice fields and fishponds. People's knowledge of the occurrence of Biomphalaria at the collection sites and the presence of Biomphalaria ova were strongly correlated with the occurrence of snails, and distance between houses and collection sites, as well as water velocity were inversely correlated with Biomphalaria occurrence (p < 0.001). The strongest predictor o f Biomphalaria occurrence was the presence of tilapia fish in fishponds. Fourteen Biomphalaria (0.8 percent of all snails) found at 6 sites were infected with Schistosoma mansoni. Suggestions are made for the utilization of local people's knowledge in snail surveys and further studies are recommended on the possible use of tilapia for biological control of Biomphalaria in fishponds, as well as modeling of S. mansoni transmission and reinfection