FioSchisto's expert perspective on implementing WHO guidelines for schistosomiasis control and transmission elimination in Brazil

The World Health Organization (WHO) recognizes schistosomiasis as one of the Neglected Tropical Diseases targeted for global elimination in the 2030 Agenda of the Sustainable Development Goals. In Brazil, schistosomiasis mansoni is considered a public health problem, particularly prevalent among vulnerable populations living in areas with poor environmental and sanitary conditions. In 2022, the WHO published a Guideline encompassing recommendations to assist national programs in endemic countries in achieving morbidity control, eliminating schistosomiasis as a public health problem, and advancing towards interrupting transmission. The perspectives presented here, collectively prepared by members of the Oswaldo Cruz Foundation's (Fiocruz) Schistosomiasis Translational Program (FioSchisto), along with invited experts, examine the feasibility of the WHO recommendations for the Brazilian settings, providing appropriate recommendations for public health policies applicable to the epidemiological reality of Brazil, and suggests future research to address relevant issues. In Brazil, the provision of safe water and sanitation should be the key action to achieve schistosomiasis elimination goals. The agencies involved in measures implementation should act together with the Primary Care teams for planning, executing, monitoring, and evaluating actions in priority municipalities based on their epidemiological indicators. Host snails control should prioritize judicious ecological interventions at breeding sites. The Information, Education, and Communication (IEC) strategy should be associated with water and sanitation and other control actions, actively involving school community. To identify infected carriers, FioSchisto recommends a two-stage approach of immunological and molecular tests to verify transmission interruption during the intervention and beyond. Praziquantel administration should be done under medical supervision at the Primary Care level. MDA should be considered in exceptional settings, as a measure of initial attack strategy in locations presenting high endemicity, always integrated with water and sanitation, IEC, and snail control. To assist decision-making, as well as the monitoring and evaluation of strategic actions, there is a need for an Information System. FioSchisto considers this systematization essential to make investments in strategic research to support the improvement of schistosomiasis control actions. Efforts toward schistosomiasis elimination in Brazil will succeed with a paradigm shift from the vertical prescriptive framework to a community-centered approach involving intersectoral and interdisciplinary collaboration.

Corrigendum: Assessment of the accuracy of 11 different diagnostic tests for the detection of Schistosomiasis mansoni in individuals from a Brazilian area of low endemicity using latent class analysis

[This corrects the article DOI: 10.3389/fmicb.2022.1048457.].

Assessment of the accuracy of 11 different diagnostic tests for the detection of Schistosomiasis mansoni in individuals from a Brazilian area of low endemicity using latent class analysis

Background

Schistosomiasis is a parasitic disease associated with poverty. It is estimated that 7.1 million people are infected with Schistosoma mansoni in Latin America, with 95% of them living in Brazil. Accurate diagnosis and timely treatment are important measures to control and eliminate schistosomiasis, but diagnostic improvements are needed to detect infections, especially in areas of low endemicity.

Methodology

This research aimed to evaluate the performance of 11 diagnostic tests using latent class analysis (LCA). A cross-sectional survey was undertaken in a low endemicity area of the municipality of Malacacheta, Minas Gerais, Brazil. Feces, urine, and blood samples were collected from 400 residents older than 6 years of age, who had not been treated with praziquantel in the 12 months previous to the collection of their samples. The collected samples were examined using parasitological (Helm Test® kit Kato-Katz), nucleic acid amplification tests -NAATs (PCR, qPCR and LAMP on urine; PCR-ELISA, qPCR and LAMP on stool), and immunological (POC-CCA, the commercial anti-Schistosoma mansoni IgG ELISA kit from Euroimmun, and two in-house ELISA assays using either the recombinant antigen PPE or the synthetic peptide Smp150390.1) tests.

Results

The positivity rate of the 11 tests evaluated ranged from 5% (qPCR on urine) to 40.8% (commercial ELISA kit). The estimated prevalence of schistosomiasis was 12% (95% CI: 9-15%) according to the LCA. Among all tests assessed, the commercial ELISA kit had the highest estimated sensitivity (100%), while the Kato-Katz had the highest estimated specificity (99%). Based on the accuracy measures observed, we proposed three 2-step diagnostic approaches for the active search of infected people in endemic settings. The approaches proposed consist of combinations of commercial ELISA kit and NAATs tests performed on stool. All the approaches had higher sensitivity and specificity than the mean values observed for the 11 tests (70.4 and 89.5%, respectively).

Conclusion

We showed that it is possible to achieve high specificity and sensitivity rates with lower costs by combining serological and NAATs tests, which would assist in the decision-making process for appropriate allocation of public funding aiming to achieve the WHO target of eliminating schistosomiasis as a public health problem by 2030.

Teachers as multipliers of knowledge about schistosomiasis: a possible approach for health education programmes

Background

In the past decade, Brazil has significantly reduced the prevalence of schistosomiasis through a combined effort of early treatment of infected people, expansion of basic sanitation infrastructure and educational measures. Despite these efforts, in some areas, prevalence of schistosomiasis exceeds 20% of the school population, who lack knowledge of the risks of the disease. Action can be taken in schools to empower this population about their health condition. This paper describes the role of the teacher as a multiplier of knowledge about schistosomiasis and proposes two different approaches to training these teachers.

Methods

This study used mixed methods to evaluate training of teachers and educational intervention with those teachers’ pupils. Two training courses, each with 40 h of face-to-face activity, were offered to 19 teachers, using two different but complementary approaches, based on theoretical references and specific educational strategies: Critical Pedagogical Approach (Training Course I, held in 2013) and Creative Play Approach (Training Course II, held in 2014).The courses included classroom activities, laboratory and field work. After the training, the teachers conducted activities on schistosomiasis with their pupils. These activities involved constructing educational materials and cultural productions. The pupils’ knowledge about the disease was evaluated before the activities and 12 months later. The teachers’ acceptance and perceptions were assessed through structured interviews and subsequent thematic analysis. The Shistosoma mansoni infection status of teachers and their students was also assessed using the Kato Katz stool test.

Results

The parasitological study showed 31.6% of the teachers and 21.4% of the pupils to be positive for S. mansoni. The teachers’ knowledge of important aspects of schistosomiasis transmission and prevention was fragmented and incorrect prior to the training. The teachers’ knowledge changed significantly after the training and they were strongly accepting of the pedagogical methods used during the training. The level of their pupils’ knowledge about the disease had increased significantly (p < 0.05). However, pupils responded that, even after the educational activities, they still had contact with the city’s contaminated waters (p > 0.05).

Conclusions

The results of this study underline the importance of schools and teachers as partners in controlling and eliminating schistosomiasis. Teacher training on the disease significantly increases their pupils’ knowledge, reflecting empowerment with regard to local health conditions.

Adherence to diagnosis followed by selective treatment of schistosomiasis mansoni and related knowledge among schoolchildren in an endemic area of Minas Gerais, Brazil, prior to and after the implementation of educational actions

Introduction

Brazilian guidelines for schistosomiasis elimination recommend regular search of infection carriers and their timely treatment. This study evaluates the effect of educational actions (EAs) among schoolchildren on adherence to diagnosis and treatment, as well as on knowledge of the disease.

Methods

In April/2013, a questionnaire was applied to 6th-to-8th-grade pupils of eight public schools to evaluate prior knowledge of disease and self-reported risk behavior. Baseline parasitological survey (PS) was done in May/2013, followed by selective treatment and cure assessment. The schools were then randomly allocated to experimental (EG) and control (CG) groups, with and without EAs, respectively. EAs were conducted for 3 months from August/2013. Questionnaire was reapplied in November/2013, April/2014, October/2014, and October/2015 to evaluate changes in knowledge about the disease and self-reported risk behavior. Two further annual PSs (May/2014 and May/2015), each followed by treatment of positives, allowed to evaluate between-group differences and intra-group changes in adherence to diagnosis and treatment, and to follow-up prevalence and intensity of infection.

Results

Adherence to diagnosis did not differ significantly between EG (84.1%) and CG (81.1%) at baseline but was significantly higher in EG in subsequent PSs. Overall, adherence to treatment was higher than 90% in all three PSs; cure was 98.4%, egg-reduction was 99.8% and reinfection, 2.8%. Prevalence fell significantly in EC (from 23.5% to 6.8%) and CG (from 21.8% to 2.4%), the same occurring with intensity (from 54.2 to 4.6 epg in EG and from 38.4 to 1.3 epg in CG). Disease knowledge increased significantly in EG and CG; knowledge about disease transmission increased significantly more in the EG. Self-reported risk behavior remained above 67% and did not differ significantly between EG and CG.

Conclusion

EAs increased adherence of schoolchildren and improved knowledge about the disease, confirming that EAs are an important tool to enhance schoolchildren participation in control campaigns.

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Educational actions improved adherence to stool testing.

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Disease knowledge also improved with educational actions.

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Risk behavior stayed high despite educational actions.

[Characterization of printed educational materials about schistosomiasis used in health education in endemic areas in Brazil]

OBJECTIVE

to characterize printed educational materials about schistosomiasis produced at federal, state and municipal levels in Brazil.

METHODS

the educational materials were characterized considering the following categories: 'format', 'parasite and intermediate host', 'definitive host (ill)' and 'disease'.

RESULTS

60 materials were assessed, three had no information about risk activities and 41 indicated more than one popular name for the disease, thus allowing greater reach among the target audience in diverse endemic areas; the biological cycle was missing or incorrect in 53 materials; the intermediate host (snail) was incorrectly illustrated, with use of stereotyped images in 39 and no image in one material; diagnosis was mentioned in 36 materials.

CONCLUSION

the printed educational materials assessed had incorrect content which may compromise health education efforts; little attention was paid to schistosomiasis diagnosis.

Ecotourism as a source of infection with Schistosoma mansoni in Minas Gerais, Brazil

BACKGROUND

In recent years, a new pattern of schistosomiasis transmission has been described which is related to recreational activities associated with rural or ecological tourism and migratory flows and accompanying changes in social dynamics in Brazil. The objective of this report is to describe two schistosomiasis outbreaks that occurred during the practice of rural tourism in Minas Gerais, Brazil, and review this pattern of transmission within the wider context of schistosomiasis control.

FINDINGS

The first outbreak was characterized by its high infection rate, showing that 59 % of the exposed eco-tourists became positive for infection with Schistosoma mansoni. In addition, all three disease transmitting species of intermediate host snails were found in the area. In the second outbreak, all members of one tourist family were infected and reported contact with water in a well-known tourist area. The malacological survey in the region revealed an infection rate with S. mansoni of 8.3 % among the collected snails.

CONCLUSIONS

Infection of urban dwellers that report contact with contaminated water associated with ecotourism represents a new pattern of disease transmission and dissemination. The infection with the disease at these occasions finds its expression in outbreaks of acute schistosomiasis among internal tourists to rural areas. Therefore, epidemiological surveillance in endemic areas should be aware of this schistosomiasis transmission pattern, and a multidisciplinary approach, most of all sanitation and health education measures, is required in order increase the efficiency of control strategies.

Evaluation of two coproscopic techniques for the diagnosis of schistosomiasis in a low-transmission area in the state of Minas Gerais, Brazil

This population study, which evaluated two parasitological methods for the diagnosis of schistosomiasis mansoni, was performed in a low-transmission area in Pedra Preta, Montes Claros, Minas Gerais, Brazil. A total of 201 inhabitants of the rural area participated in this research. Four stool samples were obtained from all participants and analysed using the Kato-Katz method (18 slides) and a commercial test, the TF-Test®, which was performed quantitatively. The data were analysed to determine prevalence, the sensitivity of the diagnostic methods, the worm burden and the definition of the "gold standard", which was obtained by totalling the results of all samples examined using the Kato-Katz technique and the TF-Test®. The results showed that the prevalence obtained from the examination of one Kato-Katz slide (the methodology adopted by the Brazilian control programme) was 8% compared to 35.8% from the "gold standard", which was a 4.5-fold difference. This result indicates that the prevalence of schistosomiasis in so-called low-transmission areas is significantly underestimated.

Effect of a participatory educational program on primary school teachers' knowledge of malaria

OBJECTIVE

To describe a participatory educational program for building up knowledge on malaria among primary school teachers in a highly endemic city.

METHODS

An observational study was conducted. A 40-hour course with a multidisciplinary and problematizing approach was held in 2008, including 46 teachers mainly from rural areas of the city of Barcelos, Northern Brazil. The participatory educational process was comprised of workshops and practical classes. A previously validated questionnaire was applied before and after the course to assess teachers' knowledge and subsequently analyzed using qualitative and quantitative approaches and open-response thematic analysis.

RESULTS

Prior to the course, teachers had little information about the transmission mechanisms, means of prevention, and the association between malaria and its vectors, and their health concepts were limited. After the course, teachers' knowledge of malaria increased and they reflected on their role in society.

CONCLUSIONS

The effect of the educational program on the construction of contextualized knowledge of malaria and health indicates the potential of the strategy developed. Continuing education processes are required for the maintenance of new knowledge and practices directed towards health promotion.

Factors related to transmission of and infection with Schistosoma mansoni in a village in the South-eastern Region of Brazil

In this transversal study, factors related to infection with and transmission of Schistosoma mansoni were explored. Based on stool examinations of two Kato-Katz smears of a single sample, the prevalences of schistosomiasis and geohelminths were established. In a multivariable analysis, sets of demographic, socio-economic and water contact pattern variables were tested for strength of relation with infection. Males presented a 3.39-times higher risk for infection than females. The age groups between 10-19 years and 20-30 years showed risks of infection 7.1- and 7.5-times higher, respectively, than the control age group between 0-10 years. Individuals practicing leisure activities had a 1.96-times higher risk than those without these activities. The malacological survey identified snails of the species Biomphalaria glabrata, Biomphalaria straminea and Biomphalaria tenagophila. Two exemplars of B. glabrata (0.53%) proved positive for S. mansoni. The socio-economic improvements observed in the locality suggest a protective and preventive effect towards infection with schistosomiasis, which requires further investigation with a longitudinal and more detailed study design. Considering our findings, a proposal for an integrated control program should be based on two pillars: one horizontal, which involves social empowerment and health education, and another more vertical, which delivers treatment and infrastructure improvements.

Rural tourism: a risk factor for schistosomiasis transmission in Brazil

This paper reports an outbreak of acute schistosomiasis among 38 tourists who rented a country house in the district of Igarapé, the metropolitan region of Belo Horizonte, Brazil, during a holiday period in 2006. A total number of 32 individuals were positive for Schistosoma mansoni. Results of stool examinations revealed individual S. mansoni egg counts per gram of faeces (epg) ranging from 4-768 epg with a geometric mean egg count of 45. The most frequent clinical symptoms were abdominal pain (78.1%), headache (75%), fever (65.6%), dry cough (65.2%) and both diarrhoea and asthenia (59.4%). A malacological survey of the area, where 22 specimens of Biomphalaria glabrata were collected, revealed three (13.6%) specimens eliminating Schistosoma cercariae. This investigation re-confirms a recently described pattern of schistosomiasis infection, resulting in the acute form of the disease and connected to rural tourism, which contributes to the spread of the disease among the middle-class and into non-endemic areas. The lack of specific knowledge about acute schistosomiasis among health services causes an increased number of unnecessary diagnostic procedures and delays in accurate diagnosis and treatment, resulting in considerable discomfort for the patients.

[Comparative analysis of parasite detection methods in vegetables for human consumption]

INTRODUCTION

vegetable contamination is a persistent health problem. The different methods of processing and diagnosis make it difficult to determine the most effective and sensitive technique.

OBJECTIVE

a comparative analysis of parasitological technique sensitivity in vegetable samples.

METHODS

a total of 30 samples were harvested -lettuce (Lactuca sativa), rocket (Eruca sativa) and watercress (Nasturtium officinale)--and later analyzed using Hoffman, Pons, and Janer (HPJ) and Faust (f) techniques. Data were analyzed, using the Bland-Altman test to evaluate the correlation and the Mann-Whitney test to compare the medians.

RESULTS

of the analyzed samples, 46.6% were positive for intestinal parasites; Balantidium coli, accounting for 20% of contamination, Entamoeba coli (21.6) and Entamoeba histolityca (5%), Trichuris trichiura (3.3%) and Strongyloides stercoralis (2.5%) The Bland-Altman test showed significant correlation between the analyzed methods. When evaluating the averages separately, there was significant difference (p = 0.05) among the results.

CONCLUSIONS

this study proved that the HPJ technique was more effective for the detection of eggs, helminth larvae and protozoan cysts in the plants under study.

[Evaluation of schistosomiasis mansoni control measures in Sabará, Minas Gerais State, Brazil, 1980-2007]

Schistosomiasis control programs in Brazil have helped reduce prevalence and the severe forms of the disease, but have failed to prevent new foci from appearing, especially on the periphery of large cities. The current article aims to assess the prevalence of schistosomiasis and the presence of intermediates hosts for Schistosoma mansoni in the district of Ravena, Municipality of Sabará, Minas Gerais State, Brazil, 27 years after implementing water treatment and specific treatment for infected individuals. Ravena responded positively to schistosomiasis control measures, with a prevalence of 2.5%. However, the district remains a potential risk area, since it displays favorable environmental and ecological factors for maintenance of the disease. For the prevalence rates to continue low, it will be necessary to invest in sanitation and health education, in addition to treatment of infected individuals.

Necator americanus infection: a possible cause of altered dendritic cell differentiation and eosinophil profile in chronically infected individuals

BACKGROUND

Hookworms survive for several years (5 to 7 years) in the host lumen, inducing a robust but largely ineffective immune response. Among the most striking aspects of the immune response to hookworm (as with many other helminths) is the ablation of parasite-specific T cell proliferative response (hyporesponsiveness). While the role of the adaptive immune response in human helminth infection has been well investigated, the role of the innate immune responses (e.g., dendritic cells and eosinophils) has received less attention and remains to be clearly elucidated.

METHODOLOGY/PRINCIPAL FINDINGS

We report on the differentiation/maturation of host dendritic cells in vitro and the eosinophil activation/function associated with human hookworm infection. Mature DCs (mDCs) from Necator americanus (Necator)-infected individuals showed an impaired differentiation process compared to the mDCs of non-infected individuals, as evidenced by the differential expression of CD11c and CD14. These same hookworm-infected individuals also presented significantly down-regulated expression of CD86, CD1a, HLA-ABC, and HLA-DR. The lower expression of co-stimulatory and antigen presentation molecules by hookworm-infected-derived mDCs was further evidenced by their reduced ability to induce cell proliferation. We also showed that this alternative DC differentiation is partially induced by excreted-secreted hookworm products. Conversely, eosinophils from the same individuals showed a highly activated status, with an upregulation of major cell surface markers. Antigen-pulsed eosinophils from N. americanus-infected individuals induced significant cell proliferation of autologous PBMCs, when compared to non-infected individuals.

CONCLUSION

Chronic N. americanus infection alters the host's innate immune response, resulting in a possible modulation of the maturation process of DCs, a functional change that may diminish their ability for antigen presentation and thus contribute to the ablation of the parasite-specific T cell proliferative response. Interestingly, a concomitant upregulation of the major cell surface markers of eosinophils was observed in hookworm-infected individuals, indicative of antigen-specific immune responses, especially antigen presentation. We showed that in addition to the postulated role of the eosinophils as effector cells against helminth infection, activated cells may also be recruited to sites of inflammation and contribute to the immune response acting as antigen presenting cells.

Esquistossomose em área de ecoturismo do Estado de Minas Gerais, Brasil

Neste trabalho, são discutidos os modos de transmissão da esquistossomose na localidade de São José da Serra, com 500 habitantes, no Município de Jaboticatubas, Minas Gerais, Brasil. A região ao redor recebe, durante todo o ano, milhares de pessoas para a prática de ecoturismo. A ocorrência de esquistossomose aguda em um casal que viajou para essa área, no carnaval de 2007, motivou este estudo. Exames de fezes foram feitos em 268 moradores, 53,6% da população total. Trinta e cinco (13%) estavam eliminando ovos nas fezes. Comparando os resultados coproscópicos com os de um inquérito feito em 2005, observa-se um aumento da proporção de positivos de 9,6% para 12,5%, entre 56 pessoas que participaram em ambos os estudos. Foram coletados 65 exemplares de Biomphalaria glabrata, sendo 1 (1,5%) positivo. No inquérito malacológico realizado em 2005, em 182 biomphalarias, nenhum exemplar foi encontrado positivo. Esses dados indicam a ocorrência de transmissão ativa de esquistossomose na área, revelando a necessidade de planejamento coordenado no desenvolvimento do setor turístico, incluindo a implantação de programas educativos integrados para a comunidade e, principalmente, para os turistas.

A combined strategy to improve the control of Schistosoma mansoni in areas of low prevalence in Brazil

Results of stool examinations for infections with Schistosoma mansoni among schoolchildren, living in a village of Minas Gerais State, Brazil, were used as an indicator to identify schistosomiasis-positive individuals within the entire population. This new approach is based on dividing the community into schoolchildren, members of households of schistosomiasis-positive and -negative schoolchildren, and members of households without schoolchildren. Each subgroup was evaluated comparing different sampling efforts with the predetermined "gold standard" to find the best relationship between detection rate and sampling effort. Consequently these results were combined, and a proposal for a new strategy, valid for an entire community, was elaborated. This alternative approach during the screening process permits to treat a similar proportion of positives as detected with 6 Kato-Katz slides of 3 stool samples, with 3-fold reduced sampling effort, enhancing the efficiency of schistosomiasis control programs in low-endemic areas.

Discursive media strategies in the journalistic construction of schistosomiasis in Jaboticatubas, Minas Gerais

Using media discourse analysis for material published by the press on schistosomiasis in the city of Jaboticatubas, the possible determining factors of narrative and discursive constructions in the diffusion of information are discussed. It was observed that media discourse treats schistosomiasis in 1962 as something from the natural order. By 1997 and 1998, the media discourse strategies reveal ideological treatment in favor of certain social segments. Situations are identified in which social agents in specific contexts construct the meanings of this endemic disease. It was concluded that the economic organization of space was a determining factor in the production and circulation of the media discourses.

Evaluation of an improved approach using residences of schistosomiasis-positive school children to identify carriers in an area of low endemicity

School children were used as indicators for the identification of schistosomiasis-positive family members in a area of low endemicity. This study was designed to improve current schistosomiasis control programs by applying this strategy to identify schistosomiasis-positive individuals in a more efficient way. The initial prevalence among school children was 8.6%. However, the prevalence among the family members of these school children increased to 15.5%. In contrast to these findings the prevalence in family members of schistosomiasis-negative school children was 3.8%. Although the applied methodology showed a relatively low sensitivity (50.0%), the high negative predictive value (87.7%) indicates that a few positive family members of school children with a negative stool result will be missed. This shows that this method of evaluation could be a strategy for a more efficient and cheaper identification of schistosomiasis-positive individuals in areas of low endemicity.

A Pedagogical approach of schistosomiasis -- an experience in health education in Minas Gerais, Brazil

The experience described here is part of an extensive program that aims to stimulate schools to develop health integrated projects from theme generators, i.e., themes that have a meaning for the community. It was developed in Jaboticatubas, a town in the metropolitan region of Belo Horizonte, capital of the state of Minas Gerais, Brazil, and the focus was schistosomiasis. The selection was based on the expressive and historical prevalence of this disease in the county, which has been known as the "capital of schistosomiasis", in a national press release since the 1960's. Schistosomiasis is also a theme pointed out by teachers as requiring more information and methodologies to work with their students, most of them living in areas of high risk of transmission. In addition, during the last years, this disease has been transmitted silently through an increasing rural tourism in that region, requiring integrated and effective control actions. The developed strategy included four schools, whose teachers, students, and families took part in the process. It emphasizes in a critical pedagogy approach, which focuses on health issues as themes that may mobilize the school community and awake the population to a work which integrates environment, health, and citizenship. The results demonstrate that teachers and students not only acquired new knowledge and methodological skills, but also gained confidence in their ability to improve their health conditions. Thus, the project promotes a critical education that can result a more permanent effect on the control of schistosomiasis as well as other benefits for the schools and for the population.

Factors associated with schistosomiasis mansoni in a population from the municipality of Jaboticatubas, State of Minas Gerais, Brazil

Jaboticatubas is a municipality in the metropolitan region of Belo Horizonte which has been a target of a wide media release as "the capital of schistosomiasis" since the 1960's. In order to give support to a work based on an integrated control, we sought to identify the disease determinants at the site. A transversal study was carried out aimed at identifying prevalence rates of the disease and factors associated with the infection in the district of São José de Almeida, and two close localities, Cipó Velho and São José da Serra, all of them located in the municipality of Jaboticatubas. A parasitological survey was performed, applying the Kato-Katz method with two slides per sample in 1186 schoolchildren which represents 77% of all registered pupils in four public schools in 2001. Among these schoolchildren a number of 101 (8.6%) proved positive for Schistosoma mansoni eggs in their stool samples. A total of 64 families, whose schoolchildren had shown to be positive for schistosomiasis, also undertook examinations. As negative control, a random sample was collected from the 206 families, whose children had proven negative for schistosomiasis. The prevalence among 270 families (1304 people) was 12%. To assess those who continued to have contact with possibly contaminated water, 1061 (81.4%) people of the 270 families were interviewed. A multivariate analysis identified the following factors associated with the infection: time of residence in the area (short period), garbage disposal (use of deserted areas), gender (male), age (from 10 to 29 years), and water contact (daily and weekly). Further analysis of these factors revealed a close correlation between water contact and the disease, with a positive significant frequency concerning almost all those items. Depending on gender and age significant variations of water contact patterns associated with leisure and professional activities were found. A malacological survey on water collections in the area identified snails of the species Biomphalaria straminea and B. glabrata. The latter showed 17 (0.6%) specimens positive for S. mansoni. Qualitative studies have complemented such evidences, which allowed us to design a reference picture and specific indicators of the disease for the local population. Those data provided the essential information to continue the development of an already ongoing educative process, as well as projects on environmental improvements.

Cellular responses and cytokine production in post-treatment hookworm patients from an endemic area in Brazil

Human hookworm infections are distributed widely in tropical areas and have a significant impact on host morbidity and human health. In the present study, we investigated the cellular responsiveness and cytokine production in peripheral blood mononuclear cells (PBMC) from Necator americanus-infected schoolchildren who had recently received chemotherapy, and compared them with non-infected endemic controls. Hookworm patients and treated, egg-negative individuals showed a lower cellular reactivity against phytohaemagglutinin (PHA) and hookworm antigen when compared with egg-negative endemic controls. The baseline production of proinflammatory tumour necrosis factor-alpha (TNF-alpha) in PBMC from infected patients and treated, egg-negative individuals was elevated. On the other hand, PHA- or hookworm antigen-induced interleukin (IL)-12 and interferon (IFN)-gamma secretion was higher in endemic controls than in hookworm patients, who either continued egg-positive or were egg-negative after treatment. Also, PBMC from endemic controls secreted more IL-5 and IL-13 than the other patient groups. Opposite to that, the spontaneous as well as the antigen-driven IL-10 secretion was lower in endemic controls when compared with the other groups. In summary, patently hookworm-infected as well as egg-negative treated patients disclosed an elevated spontaneous cellular secretion of proinflammatory TNF-alpha, a prominent secretion of regulatory Th2-type IL-10 and an impaired production of IL-12, IFN-gamma, IL-5 and IL-13.

Treatment options in the management of Ascaris lumbricoides

Infection with Ascaris lumbricoides constitutes one of the most common helmintic diseases in the world, especially in tropical and subtropical regions. Transmission of this disease involves environmental contamination with eggs, and therefore, is classified as a soil-transmitted disease. The public health importance of ascariasis is made evident by the high number of infected individuals suffering its consequences, which can become severe, depending on the worm burden. Since the introduction of benzimidazoles, chemotherapy has improved significantly, offering fast and direct effects at relatively low cost, as a result of the simple and safe application of these drugs. Unfortunately, the effects are not long-lasting or permanent. The intervention with chemotherapy alone constitutes a fast and efficient way to reduce the worm burden in a population of high prevalence, but does not avoid reinfection. Therefore, the option of integrated control programmes based on chemotherapy in combination with sanitation and health education, together with strong community involvement, must be considered in order to ensure the positive long-term effects of such programmes.

First report on the presence of Biomphalaria straminea in the municipality of Jaboticatubas, State of Minas Gerais, Brazil

This is the first report on occurrence of Biomphalaria straminea in the district of São José de Almeida (municipality of Jaboticatubas) State of Minas Gerais, Brazil. The presence of B. glabrata and B. tenagophila had already been reported in this area. Such municipality is part of the metropolitan region of Belo Horizonte and comprises 60% of the Tourist Complex of Serra do Cipó. Since the 1950s throughout the 1990s, a schistosomiasis prevalence ranging from 15 to 40% has been observed. Although no B. straminea specimen has been found naturally infected in the region, descendants of these snails collected in the area, showed to be experimentally susceptible to Schistosoma mansoni infection reaching rates from 14.6 to 28.6%. Even not being found naturally infected, in the State of Minas Gerais, the possibility that the species B. straminea may keep endemicity foci of schistosomiasis should be regarded, as in the Northeastern region of Brazil where the high density of this planorbid and the social-economic and sanitary conditions enable to the transmission.

[Effects of detergents and disinfectants on the development of Ascaris lumbricoides eggs]

Ascaris lumbricoides infection is acquired via ingestion of embryonated eggs of the parasite, thus justifying the search for ovicidal compounds. We studied the effect of 16 household and laboratory detergents and disinfectants on the embryogenesis of this helminth. Children carrying this infection were treated with levamisole. Eliminated female worms were collected and dissected to obtain eggs from the uteri. The eggs were placed in contact with various products at different dilutions and for various periods of time. After washing, eggs were incubated at 28 grades C for 20 days, for viability tests and to determine the embryonation rate. Only one product completely inhibited the embryonation of eggs at every dilution and for every time period tested. Five products inhibited more than 50% of embryonation, while six inhibited less than 50%. Three products showed no effect on embryonation, while for one the percentage of embryonated eggs was higher than in the control tubes.

Prevalência de helmintos intestinais em três mesorregiões do Estado de Minas Gerais

Foi realizado um levantamento das helmintoses intestinais em 18.973 escolares do primeiro grau (7 a 14 anos), da rede pública do Estado de Minas Gerais, utilizando o método de Kato-Katz de exame de fezes (duas lâminas por amostra). Foram estudadas 3 mesorregiões: Triângulo Mineiro/Alto Paranaíba (60 municípios), Noroeste de Minas (13) e Sul/Sudoeste (144). Entre os escolares examinados, 15.545 (82%) estavam negativos, 2.863 (15%) monoparasitados e 565 (3%) poliparasitados. A prevalência de A. lumbricoides foi de 10,3%, de T. trichiura 4,7%, de ancilostomídeos 2,9%, de E. vermicularis 1,2%, de H. nana 0,4% e de Taenia sp 0,2%. As maiores prevalências de helmintos/mesorregião foram de 24,2% para T. trichiura e 18,7% para A. lumbricoides (Sul/Sudoeste) e 12,1% para ancilostomídeos e 0,7% para Taenia sp (Noroeste de Minas). As helmintoses intestinais continuam sendo um grave problema de saúde pública, inclusive em áreas onde as condições socioeconômicas são mais favoráveis.

[Prevalence of intestinal helminths in three regions of Minas Gerais State]

A parasitological assay of feces, through the Kato-Katz method, was undertaken in 18,973 schoolchildren (7 to 14 years old), at primary school level, from a public school of the State of Minas Gerais. Three mesoregions were studied: Tri ngulo Mineiro/ Alto Para ba ( 60 municipalities); northwest Minas Gerais (13) and south/south-west regions of Minas Gerais (144). Among the examined children, 15,545 (82%) were negative; 2,863 (15%) were infected with a single species of helminthes and 565 (3%) were infected by more than one species. The prevalence rates were: A. lumbricoides 10.3%; T. trichiura 4.7%; hookworm 2.9%; E. vermicularis 1.2%; H. nana 0.4% and Taenia sp 0.2%. The largest helminthes prevalence/mesoregion were for T. trichiura (24.2%) and A. lumbricoides (18.7%) in the south/south-west region; hookworm (12.1%) and Taenia sp (0.7%) in the northwest region of Minas Gerais. Intestinal helminthiasis is still regarded as a serious public health problem, including regions where the socio-economic conditions are more favorable.

In vitro study on thiabendazole action on viability of Ascaris lumbricoides (Lineu, 1758) eggs

The in vitro activity of thiabendazole on Ascaris lumbricoides eggs, which were recovered from uteri of worm excreted after chemotherapeutic treatment, was studied. Four concentrations of the drug were used: 1 - 2.5 - 5 - and 10 ppm during 24, 48 and 72 hours of exposure. Subsequently, the eggs were centrifuged, washed three times and H(2)SO(4)0.1N was added. The eggs were maintained in an incubator for 20 days at 28 degrees C. Finally, the percentage of embryonated eggs was determined under a lightmicroscope at a 100X magnification. After 48 and 72 hours of thiabendazole exposure, at a concentration of 10ppm, the drug showed complete inhibition of egg embryonation.

Susceptibility and resistance to Schistosoma mansoni reinfection: parallel cellular and isotypic immunologic assessment

Cellular and humoral immune responses to Schistosoma mansoni antigen preparations were evaluated in individuals presumed to be susceptible or resistant to reinfection after chemotherapeutic cure. A consistent proliferative increase in the response to soluble egg antigen (SEA) was observed post-treatment in both the susceptible and resistant groups. However, this change was not related to resistance. Isotype studies showed that IgM antibody levels to soluble worm antigen preparation (SWAP) and cercariae antigens were significantly higher in the resistant group than in the susceptible group. Post-treatment, an increase in IgE anti-SWAP and anti-schistosomular tegument (STEG) responses and a decrease in IgG4 anti-SEA and anti-STEG responses were observed in the resistant group. These finding are similar to those we have reported previously for a putative resistant group termed endemic normals, and are compatible with immunologic studies in different endemic areas. Together, these findings indicate that even on the population level, high IgE specificities coupled with low IgG4 specificities correlate well with documented resistance to reinfection.

Re-evaluation of schistosomiasis mansoni in Minas Gerais, Brazil. III. "Noroeste de Minas" mesoregion

This study was conducted to assess the presence of schistosomiasis mansoni in the "Noroeste de Minas" mesoregion, an area considered non-endemic. A malacologic survey and parasitologic stool examinations were undertaken in 13 municipalities of the mesoregion. A sample of 3,283 primary school students was submitted to fecal examination by the Kato-Katz method. A total of 3,627 planorbids was collected and examined. The molluscs were identified as Biomphalaria straminea in seven municipalities (Unaí, Bonfinópolis de Minas, Paracatu, Jaão Pinheiro, Vazante, Lagamar and Lagoa Grande) and as Biomphalaria peregrina in one (Presidente Olegário). All planorbids were negative for Schistosoma mansoni. Four students were diagnosed with schistosomiasis in the municipalities of Buritis, Formoso, Paracatu and Unaí, but none of these cases was considered autochthonous. The data obtained indicate that the "Noroeste de Minas" mesoregion continues to be non-endemic for schistosomiasis mansoni, although the presence of intermediate hosts associated with parasitized individuals emphasizes the need for epidemiological surveillance of schistosomiasis in this mesoregion.

Comparison of antibody isotype responses to Schistosoma mansoni antigens by infected and putative resistant individuals living in an endemic area

The isotypic patterns of antibodies against Schistosoma mansoni antigenic preparations from eggs (SEA), adult worms (SWAP) and cercariae (CERC) have been studied in sera from two groups of individuals living in an area endemic for S. mansoni. One of the groups was comprised of individuals diagnosed as having S. mansoni infections based on their patency, i.e. those passing eggs in their faeces (patent infections, PI). The other group has been consider 'putatively resistant' due to their residence in an endemic area, their documented exposure to positive transmission sites, and their repeated negativity upon stool examinations (endemic normals, EN). There are strong specific responses of IgG1, IgG4 and IgM, particularly to SEA and CERC, by both groups. The reactivities of all isotypes were lower to SWAP. The responses of IgG4, IgM and IgE anti-CERC in EN and PI are higher than those found in normal individuals from outside endemic areas. In general, EN individuals express a relative higher level of anti-STEG IgE as compared to IgG4. On the other hand the pool of sera from PI showed the opposite pattern of higher IgG4 as compared to IgE. Several correlations are seen between isotypic responses to SEA, SWAP and CERC based on comparisons to the anti-SWAP IgE responses of the individuals in the two groups. These comparisons indicate the presence of distinct immunologic differences between individuals in the PI and the EN groups.

Schistosomiasis mansoni in the region of the Triângulo Mineiro, State of Minas Gerais, Brazil

In order to reevaluate the possible presence of schistosomiasis mansoni in the Triângulo Mineiro, one of the areas of the State of Minas Gerais where this parasite is not commonly found, malacological survey and fecal examinations were undertaken in the region between October 1990 and June 1992. A sample of 7,032 1st grade school children from 29 counties had their feces examined using the Kato-Katz method. Amongst the children examined, two from Planura and one from each countie of Capinópolis, Conceição das Alagoas, Uberaba, Uberlândia, Prata and Gurinhatã were positive for Schistosoma mansoni. None of the children were identified as being autoctonous cases. In the malacological survey, 5,406 planorbid snails were examined. The specimens were identified morphologically and examined for S. mansoni by squashing between glass plates. The species were identified as Biomphalaria tenagophila in three counties, as B. straminea in ten and B. intermedia in 16. No snails were found in eight other counties studies. The snails were found to be negative for S. mansoni. The presence of intermediate hosts for S. mansoni, associated with parasitized individuals emphasizes the necessity of epidemiological surveillance for schistosomiasis in the region of Triângulo in the State of Minas Gerais.

Interferon-gamma production by peripheral blood mononuclear cells from residents of an area endemic for Schistosoma mansoni

During human schistosomiasis host responses to antigens of various parasite life-cycle stages may contribute to whether the severe, hepatosplenic state develops or the patient remains relatively asymptomatic throughout infection, and may play a role in resistance. This study evaluated production of interferon gamma (IFN-gamma) in vitro by schistosome antigen-stimulated peripheral blood mononuclear cells (PBMCs) from asymptomatic patients, and by PBMCs from apparently uninfected, untreated persons living in areas endemic for Schistosoma mansoni ('endemic normals'). IFN-gamma production parallels PBMC proliferation in that schistosomal egg antigens stimulate patent patients' cells poorly, but strongly stimulate PBMCs from 'endemic normals'. This is proportionally true for antigens from adult worms and cercariae. Although asymptomatic patent patients' cells produced little or no IFN-gamma in response to the 3 schistosomal antigenic extracts, their PBMCs, and PBMCs from 'endemic normals', produced expected amounts of IFN-gamma when exposed to phytohaemagglutinin. This implies that persons with patent infections have schistosome antigen-specific defects in their ability to respond to IFN-gamma production that are not exhibited by putatively resistant 'endemic normals'.

Immunological profiles of patients from endemic areas infected with Schistosoma mansoni

Crude extracts of eggs (SEA) adult worms (SWAP) or cercariae (Cerc) have been used to stimulate Peripheral Blood Mononuclear cells (PBMC) and have provided rather distinct profiles of responses in different types of patients. In general it is clear that patients with early infections respond strongly to SEA while response to SWAP are develop more slowly. As infection progresses into the more chronic phases, a general pattern is seen which leads to lower anti-SEA proliferative responses in the face of higher responses to SWAP and variable anti-cerc responsiveness. Cured not re-exposed patients express very high levels of anti-SEA proliferation. It has recently been seen that those individuals who live in endemic areas and have continued water contact, but are repeatedly stool-negative (who are presumed to have self-cured or be putatively resistant; endemic normals) are strongly responsive to antigenic extracts, particularly to SEA. Furthermore, our results show that endemic normal individuals have significantly higher IFN gamma production upon PBMC stimulation with schistosome antigens than infected individuals. With the emergence of more studies it is becoming apparent that both the intensity and the prevalence of a given area may influence or shape the general responsiveness of the population under study.

[The susceptibility of Planorbidae from the metropolitan area of Belo Horizonte, MG (Brazil) to Angiostrongylus costaricensis (Nematoda, Angiostrongylidae)]

Biomphalaria glabrata (control), B. tenagophila and B. straminea from our laboratory colonies iniciated with molluscs collected in the municipality of Belo Horizonte, MG (Brasil), were experimentally infected with first-stage larvae of Angiostrongylus costaricensis. The number of molluscs of each species exposed was 139, 77 and 149. About 25 days later, surviving molluscs were individually examined by artificial digestion. Of 87 B. glabrata examined, 62 (71.3%) were positive and between one and 61 third-stage larvae were found; of 42 B. tenagophila, 21 (50.0%) contained between one five third-stage larvae; and of 89 B. straminea, 69 (77.5%) presented between one and 72 third-stage larvae. The three molluscan species are susceptible to A. costaricensis infection, but B. glabrata and B. straminea are most suitable for maintaining the nematode cycle in laboratory.

[Sarasinula marginata (Semper, 1885) (Mollusca, Soleolifera) from Belo Horizonte (MG, Brasil) as a potential intermediate host of Angiostrongylus costaricensis Morera, Cespedes, 1971]

Specimens of Sarasinula marginata were collected in kitchen and house gardens of Belo Horizonte, Minas Gerais. The susceptibility of these molluscs for Angiostrongylus costaricensis was tested by infecting 15 laboratory--reared slugs (F1). The positivity demonstrated was of 80.0%.

Development of Ascaris lumbricoides eggs from females eliminated after chemotherapy in man

The development of Ascaris lumbricoides eggs obtained from females eliminated after treatment of infected individuals with a single oral dose of the antihelminthic drugs thiabendazole (50 mg/kg--33 patients) or levamisole (250 mg--independent of body weight--20 patients) was studied. Every female eliminated up to 72 h after treatment were dissected, the uterus isolated and sectioned into small fragments. The eggs were transferred to plastics tubes and incubated at 28 degrees C in 0.1 N H2SO4 for 100 days. Every 20 days, starting from the 20 th up to the 100 th day, the extent of egg embryonation ratio was determined. The culture of A. lumbricoides eggs obtained from females from patients treated with thiabendazole did not contain embryonated eggs until the final period of observation. In contrast, the eggs obtained from females eliminated by patients treated with levamisole (control) presented an embryonation rate of 0.0-98.0% in the same period.

Viability of Ascaris lumbricoides eggs eliminated after anti-helminthic therapy

The viability of Ascaris lumbricoides eggs passed in the feces was evaluated after treatment of patients with one of the anti-helminthic drugs (thiabendazole, levamisole, cambendazole, pyrantel pamoate, mebendazole or praziquantel). For each drug, a group of 5 children was selected and their feces collected 24 h before treatment and 24, 48 and 72 h after drug administration, except for mebendazole, with the feces being collected throughout the period of treatment. After sedimentation, the total amount of eggs from each collection was transferred to tissue culture flasks containing 10 ml H2SO4 0,1N, with the addition of 3 drops of a miconazole solution, and incubated at 28 degrees C, individually, for 80 days. The flasks were maintained open and the culture were oxygenated daily by manual agitation. On the 80th day of culture, 20-days-old albino mice were inoculated with 3,200 embryonated eggs, per os. Larvae were recovered from their lungs and hearts, on the 8th day after infection, according to Baerman's method (Morais, 1948). Thiabendazole showed 100.0% ovicidal capacity as early as 48 h after treatment. Inhibition of embryonal development was observed when thiabendazole was used. This drug also had an effect on the eggs infectivity when inoculated into normal mice. No significant effect on embryonal development was observed for the other drugs tested.

[The study of Ascaris lumbricoides in the laboratory]

With the purpose of standardising techniques for the laboratory study of Ascaris lumbricoides, faeces were collected from children parasitised by A. lumbricoides, during a 24 hour period. The fecal samples were sieved and resuspended several times in water. The sediment containing the eggs was cultivated in H2SO4 0.1N in tissue culture flasks, at 28 degrees C. The culture of embryonated eggs was determined every ten days starting from the 20th day of culture achieving around 98.0% embryogeny on the 80th day of culture. The best day to recover larvae from mice was determined by infecting 9 groups of 5 mice per os with 200 embryonated eggs/mouse. Each mouse was sacrificed by cervical rupture starting on the 4 day up to the 12 day of infection. On the 8 day after the infection 0.45% of the larvae were recovered from the lungs. The inoculum determination was performed by using 5 groups of 10 infected mice with 200, 400, 800, 1,600 and 3,200 embryo eggs/mouse. The best age for recovery of infection was achieved by using 4 groups animals, with 5 mice/group, with age varying from 20 to 50 days and an inoculum of 3,200 eggs. The best recovery (1.9% was obtained from the group of 20 days of age.

[Schistosomiasis mansoni in the southwest of the State of Minas Gerais (Brazil)]

A new focus of schistosomiasis mansoni at Passos, a town in the Southwest of the State of Minas Gerais (Brazil), region until now considered free of the disease is reported. Malacological surveys showed Biophalaria glabrata naturally infected with Schistosoma mansoni in a country club near Passos. All B. straminea captured at the pisciculture station of the Furnas hydroelectric dam were negative. Six out of seven individuals living in the country club were found to be infected with S. mansoni, including four children who had never been out of Passos. The epidemiological importance of these findings is discussed.

[Interrelation of parasitic diseases and hypovitaminosis A. Schistosoma mansoni infection and the serum level of retinol in the population of an endemic area of Minas Gerais (Brazil)]

The interrelation between schistosomiasis and the retinol blood levels was studied in a double blind method, by comparing the serum vitamin A of the infected and non-infected group of an endemic area of Schistosoma mansoni infection. The infected group was characterized by 106 parasitized persons in the intestinal and hepatointestinal forms, who eliminated less than 500 eggs/gram of feces (Modified Kato's method); the non-infected group was characterized by 112 inhabitants of this endemic area without eggs in the stools and presenting negative intradermal reactions, and absence of previous specific treatment. The blood levels of retinol was determinated using trifluoracetic acid method, regarding the normal levels > 20,0mg/100ml. The results of this study point out the absence of correlation between S. mansoni infection and blood levels of vitamin A.

[1st authochtonous cases of schistosomiasis mansoni in the Northwest region of the State of Minas Gerais (Brazil)]

São relatados os primeiros casos autóctones de esquistossomose mansoni, originários da cidade de Paracatu, Noroeste do Estado de Minas Gerais, Brasil, região até o momento considerrada indene para esta parasitose. Trata-se de oito pacientes com idade entre 12 e 14 anos, e que nunca haviam se ausentado da localidade. Os levantamentos malacológicos proporcionaram a coleta de 11.471 exemplares de Biomphalaria straminea, todos negativos para Schistosoma mansoni. Foram sugeridas medidas que, se colocadas em prática, poderiam controlar a parasitose na cidade.