Childhood diarrhoea symptoms, management and duration: observations from a longitudinal community study

This study examined the evolution and duration of diarrhoea episodes observed in a community setting, with regard to symptoms and carers' responses. The study group comprised 1156 children, aged 0-36 months, who were followed-up with twice-weekly home visits in 30 sampling areas in the city of Salvador, northeast Brazil. A total of 2403 diarrhoea episodes (mean duration: 2.9 days) were recorded. The number of soft/liquid motions per day (3.6) did not vary significantly with duration, but other symptoms were more commonly reported in the longer episodes. However, when the data were analysed by day of the episode, rather than the episode's overall duration, the reported frequency of fever and vomiting declined significantly with time. During the course of an episode, rehydration, medication and care-seeking also showed a decline in frequency after the first or second week. As episodes continue, less rehydration and medical care are provided by carers, whereas they ought to be maintained because of the continued purging and cumulative effect of the symptoms. Since most cases of diarrhoea are managed at home, it is important to understand how to encourage better management of the longer episodes, which cause an increasing proportion of mortality in some countries.

[Tuberculosis in Salvador, Brazil: costs to health system and families]

OBJECTIVE

Tuberculosis is one the greatest causes of mortality worldwide, but its economic effects are not well known. This study had the objective of estimating the costs to the public and private healthcare systems and to families of tuberculosis treatment and prevention.

METHODS

This study was made in the municipality of Salvador, State of Bahia, Brazil, in 1999. Data for estimating the costs to the healthcare system were collected from the Department of Health, healthcare facilities and a philanthropic institution. The public and private costs were analyzed using cost accounting methodology. Cost data relating to families were collected by means of questionnaires, and included data on transportation, food and other expenses, and also income losses associated with this disease.

RESULTS

The average cost of treating one new case of tuberculosis was approximately US$103. The cost of treating one multiresistant patient was 27 higher than this. The cost to the public services consisted of 65% on hospitalization, 32% on treatment, and only 3% on prevention. The families committed around 33% of their income on expenses related to tuberculosis.

CONCLUSIONS

Despite the fact that the families did not have to pay for medications and treatment, given that this service is offered by the State, the costs to families related to loss of income due to the disease were very high. The proportion of public service funds utilized for prevention is small. Greater investment in prevention campaigns not only might diminish the numbers of cases but also might lead to earlier diagnosis, thus reducing the costs associated with hospitalization. The lack of an integrated cost accounting system makes it impossible to visualize costs across the various sectors.

Childhood anemia prevalence and associated factors in Salvador, Bahia, Brazil

A cross-sectional study was conducted in 1996 to estimate the prevalence of anemia in a stratified sample of 603 preschool children and identify factors associated with the disease. Hemoglobin assays were conducted in finger-prick blood samples using a Hemocue hemoglobinometer. Anemia was defined as hemoglobin below 11.0g/dl. Logistic regression analysis was used to evaluate the potential associations. Observed anemia prevalence was 46.3%. Associated factors were: the 6-12-month and 12-24-month age brackets, the lowest tertiles for iron density and protein content dietary intake, and any degree of deficit in the height-for-age anthropometric parameter. Inadequate physical, sanitary, and environmental conditions in the home were associated with a significantly increased risk of anemia. Anemia constitutes an important health problem in this study's child population. Improvements in living conditions and dietary quality could contribute to a reduction in anemia prevalence.

Neonatal BCG protection against leprosy: a study in Manaus, Brazilian Amazon

There is clear evidence that BCG protects against leprosy, but cross-immunity with environmental mycobacteria can interfere with vaccination protection. Some have cast doubts whether BCG vaccination can offer a significant impact against leprosy in the Brazilian Amazon, which is an endemic area for leprosy and with a high prevalence of environmental mycobacteria. This study was designed to estimate the vaccine effectiveness of neonatal BCG against leprosy in Amazon region, in Brazil. This is a cohort study nested in a randomized community trial. The study had two main results. First, neonatal BCG vaccination in Brazilian Amazon elicited protection of 74% (95% CI 57-86) against all forms of leprosy cases. Second, the highest protection was observed for multibacillary cases, 93% (95% CI 71-98). It is concluded that the study provides evidence that neonatal BCG may have an important and overlooked impact on the occurrence and transmission of leprosy, maybe even more in the future when the cohort which received a high coverage of BCG reaches the age of high incidence of leprosy.

Childhood stunting in Northeast Brazil: the role of Schistosoma mansoni infection and inadequate dietary intake

OBJECTIVE

To evaluate the relationship between stunting, Schistosoma mansoni infection and dietary intake in schoolchildren.

DESIGN

This is a cross-sectional study. Two stool samples were obtained from each child and examined quantitatively for the presence of S. mansoni, Ascaris lumbricoides and Trichuris trichiuria eggs. Information on dietary intake, and demographic, biologic and socioeconomic variables was elicited during the in-home survey. Logistic regression was used to evaluate the association between stunting (height for age < -2s.d.), parasitic infection and food consumption.

SETTING

The study was carried out in the city of Nazaré, located in the Recôncavo region of the State of Bahia, Northeastern Brazil.

SUBJECTS

The sample consisted of 461 children 7-14 y old, 228 boys and 233 girls, recruited from public schools.

RESULTS

Of the children studied, 55.1% presented with S. mansoni infection and 22.1% were stunted. The median protein, lipid and carbohydrates intake were 47.8, 36.0 and 248.2 g/day, respectively. The median caloric consumption was 1527.0 kcal (6388.97 kJ/day). The analysis indicated that children heavily infected (> or = 400 eggs/g of stool) with S. mansoni had a 2.74-fold (95% CI: 1.32-5.67) higher risk of stunting than uninfected children, and those with inadequate intake of lipid (< 36 g/day) had a 1.83-fold (95% CI: 1.05-3.20) increased risk of stunting compared to those with adequate diets.

CONCLUSION

Heavy S. mansoni infection and inadequate dietary intake of fat in schoolchildren play a significant and independent role in the development of stunting. This meaning that nutritional interventions in this age group in S. mansoni endemic areas must include the diagnosis and treatment of the infection associated with dietary measures.

SPONSORSHIP

This study was supported by the Thrasher Foundation. Sandra Maria Conceição Pinheiro is a National Council on Technological Development Scholarship Awardee (CNPq), #302228/81-0.

Lower prevalence of reported asthma in adolescents with symptoms of rhinitis that received neonatal BCG

BACKGROUND

BCG is a vaccine used against tuberculosis and leprosy and is an immunostimulant that primes T(H)1 lymphocytes to produce cytokines that antagonize atopy both in animal models and in man. Considering that atopy is the main risk factor for asthma, one can hypothesize that vaccination inducing T(H)1 responses, such as BCG, can be protective against asthma.

METHODS

OBJECTIVE

To estimate the association between neonatal BCG vaccination and prevalence of asthma among adolescents.

STUDY DESIGN

Cross-sectional study with schoolchildren aged 12-16 years. The presence of a scar compatible with BCG was used as a surrogate of neonatal vaccination. A self administered structured questionnaire was prepared based on that used by the International Study of Asthma and Allergies in Childhood. The prevalence of asthma was categorized according to the report of lifetime wheeze, lifetime asthma, lifetime asthma among those referring allergy and among those referring allergy and sneezing.

RESULTS

Neonatal BCG vaccination was not associated with the overall prevalence of reported wheezing or asthma. However, in the subgroup reporting current allergy and sneezing, neonatal BCG was associated with a 37% reduction of prevalence of lifetime asthma.

CONCLUSIONS

In the population we surveyed, neonatal BCG scar was associated with a reduction in the risk of asthma only in individuals with a past history suggestive of allergic rhinitis.

Quimioprofilaxia na prevenção da tuberculose

A quimioprofilaxia da tuberculose constitui-se numa medida terapêutica para a prevenção da infecção pelo Mycobacterium tuberculosis ou para evitar o desenvolvimento da doença nos indivíduos infectados. Geralmente baseia-se na administração de isoniazida. Entretanto, o uso de rifampicina e pirazinamida vem sendo recentemente introduzido. Este trabalho tem como objetivo revisar os resultados dos principais estudos que avaliaram as indicações da quimioprofilaxia com isoniazida e sua associação com outras drogas, sua efetividade na prevenção da tuberculose considerando os diversos grupos de risco, e as alternativas do uso de outros esquemas. Procedeu-se à revisão sistemática da literatura, com ênfase em ensaios clínicos e meta-análises. Foram consultados também os documentos oficiais. Foram selecionados aqueles estudos que envolveram ensaios clínicos ramdomizados com uso de isoniazida, rifampicina ou pirazinamida em pacientes HIV positivos ou negativos. Concluiu-se que a isoniazida continua sendo efetiva na prevenção da tuberculose na população de indivíduos HIV negativos e de HIV positivos. A dose padrão de 5 a 15 mg/kg/dia tem mostrado proteção similar para períodos de tratamento de seis e doze meses. O risco de desenvolver hepatite foi menor que 1%, sendo recomendada sua utilização com acompanhamento nos indivíduos com idade superior a 35 anos e usuários de álcool. Os estudos com esquemas de tratamento utilizando outros medicamentos não foram conclusivos, sendo necessária a realização de novos estudos para avaliação da efetividade desses esquemas em populações de alto risco de desenvolver tuberculose.

The globalization of epidemiology: critical thoughts from Latin America

BACKGROUND

Epidemiology in Latin America, as in the rest of the world, has been developed for the purpose of contributing towards understanding the causes and determinants of the phenomena of health and disease in specific contexts. However, in that continent it has specific characteristics.

METHODS

The paper explores epidemiology in the Latin American continent, emphasizing on the one hand epidemiology as a knowledge-producing, scientific discipline, and on the other hand, epidemiology in praxis, with its firm commitment to contributing towards transforming the health of the population.

RESULTS

It has been possible to identify at least eight idiosyncrasies that characterize epidemiology in Latin America. It is being forged with a strong connection to the evolution of the discipline in an international context; however, it has its feet firmly planted in reality, seeking to extract from that reality elements that may contribute towards diminishing the serious health problems in that society.

CONCLUSIONS

This paper presents a picture of the development of epidemiology in Latin America. It is very clear that as well as a lively, intense, intellectual debate, there is a frantic search for alternatives that will increase Latin American populations' possibilities of survival. However, one important aspect is that these two elements-theory and praxis-present consistent dialectic relationships and feedback; this is the main wealth of Latin American epidemiology.

Design of the Leprosy Component of the Brazilian BCG Revaccination Trial for Assessing BCG Effectiveness against Leprosy in School Children

BACKGROUND

BCG vaccination confers protection against leprosy, and vaccination among household contacts has been recommended in Brazil. Nevertheless, vaccination of the entire community against leprosy is not advocated as leprosy has low incidence in most populations. Despite that, in Brazil, BCG vaccination is recommended among school children to prevent tuberculosis and this large scale vaccination may also affect the occurrence of leprosy, which led to investigations of its impact on leprosy in endemic areas of Brazil.

OBJECTIVES

To estimate the effectiveness against leprosy of a dose of BCG vaccine given to school children in a population with a high coverage of neonatal BCG. Long term objectives are to compare the impact of vaccination among schoolchildren with the existing recommendation to vaccinate household contacts of leprosy.

STUDY DESIGN

Cluster randomized controlled field trial with no placebo.

STUDY POPULATION

Children aged 7 to 14 years attending state schools with high coverage of neonatal BCG.

METHODS

286 state schools in the city of Manaus, Brazil, were randomized to receive BCG or not. Identifying information was collected for 152,438 school children, of whom 72,980 are in intervention schools. BCG vaccination was given intradermically to children in schools allocated to vaccination. Follow-up relies on ascertainement of cases diagnosed at the health services and notified to the reference center for leprosy.

Risk factors for infection with Giardia duodenalis in pre-school children in the city of Salvador, Brazil

A cross-sectional study of 694 children aged 2 to 45 months selected from 30 clusters throughout the city of Salvador, Bahia (pop. 2.3 million) was carried out as part of a longitudinal study of diarrhoea in order to identify risk factors for infection with Giardia duodenalis. Variables studied included three social and demographic factors (such as mother's education and marital status), five relating to the peri-domestic environment (rubbish disposal, open sewers, paving of the street), seven relating to the home itself (house construction, susceptibility to flooding, water supply and sanitation) as well as a score for hygiene behaviour based on structured observation. After multivariate analysis using a hierarchical model, only four significant risk factors were found: (a) number of children in the household under five years (b) rubbish not collected from the house (c) presence of visible sewage nearby, and (d) absence of a toilet. All four were significant at the 1% level.

Childhood diarrhea and observed hygiene behavior in Salvador, Brazil

Brief biweekly home visits, made as part of a cohort study of diarrhea in young children under age 5 years that was carried out in Salvador, Brazil, in 1998-1999, were used as a low-cost way to collect structured observation data on domestic hygiene behavior. Field-workers were trained to check a list of 23 forms of hygienic or unhygienic behavior by the child or the child's caretaker, if any behaviors were seen during the visit. Children were grouped according to whether mainly unhygienic behavior or mainly hygienic behavior had been recorded. This permitted study of the determinants of hygiene behavior and of its role in the transmission or prevention of diarrheal disease. Observations were recorded on roughly one visit in 20. Households with adequate excreta disposal were significantly more likely to be in the "mainly hygienic" group. The prevalence of diarrhea among children for whom mainly unhygienic behavior was recorded was 2.2 times that among children in the "mainly hygienic" group. The relative risk for prevalence was 2.2 (95% confidence interval: 1.7, 2.8). The relative risk fell to 1.9 (95% confidence interval: 1.5, 2.5) after data were controlled for confounding, but the difference was still highly significant.

Rates of adverse reactions to first and second doses of BCG vaccination: results of a large community trial in Brazilian schoolchildren

OBJECTIVE

To evaluate the incidence of adverse reactions to first and second bacille Calmette-Guérin (BCG) vaccination in schoolchildren.

SETTING AND DESIGN

Enhanced surveillance in a Brazilian trial. Suspected reactions were reported to a nurse who visited cases and completed a standard form.

RESULTS

Among 71341 schoolchildren studied, 33 reactions were reported. Of these, 25 fulfilled the criteria, resulting in a rate of one per 2854 vaccinations, with no deaths or BCG-osis. Reactions to second doses were more common than to first BCG vaccinations, but this difference was not statistically significant.

CONCLUSIONS

Adverse reactions to a second dose of BCG may be more frequent than reactions to a first dose, but they are still rare events.

A comparison of dual skin test with mycobacterial antigens and tuberculin skin test alone in estimating prevalence of Mycobacterium tuberculosis infection from population surveys

SETTING

City of Manaus, Amazonas, Brazil.

OBJECTIVE

To compare estimates of Mycobacterium tuberculosis infection prevalence obtained using traditional tuberculin skin test (TST) criteria and dual skin test (DST) data.

METHODS

A total of 1070 schoolchildren received DST with tuberculin and four environmental mycobacteria sensitins. Responses were classified as sensitin-dominant, tuberculin-dominant or non-dominant. Positive predictive values (PPV) were defined using 'narrow' and 'wide' standards based on DST responses. These predictive values were derived for each category of tuberculin indurations, and were used to calculate the prevalence estimates.

RESULTS

Using DST data, the estimates of M. tuberculosis prevalence for scar-negative children were 7.4% (M. avium) and 7.8% (M. scrofulaceum) using the 'narrow' standard, and 16.9% (M. avium) and 15.2% (M. scrofulaceum) using the 'wide' standard. The percentage with TST > or =10 mm was 11.5%. Scar-positive children had higher estimates using both the 10 mm cut-off and DST data.

CONCLUSION

In settings with a relatively low prevalence of M. tuberculosis infection and high cross-reactivity with environmental mycobacteria, DST can help to assess the validity of traditional thresholds for estimating the prevalence of M. tuberculosis infection. DST data with environmental antigens and tuberculin do not distinguish BCG-induced cross-reactivity.

Papel da epidemiologia no desenvolvimento do Sistema Único de Saúde no Brasil: histórico, fundamentos e perspectivas

O autor apresenta a sua interpretação sobre a história recente da epidemiologia no Brasil e sobre o papel desta disciplina e dos seus praticantes no desenvolvimento do Sistema Único de Saúde (SUS). Os avanços da epidemiologia no país, tanto na sua vertente acadêmica como na sua vertente aplicada aos serviços de saúde, são notórios e são várias as evidências deste intenso desenvolvimento. Um marco neste processo foi a I Reunião Nacional de Ensino e Pesquisa em Epidemiologia, realizada em 1984, quando foi criada a Comissão de Epidemiologia da ABRASCO e foram estabelecidos os fundamentos não somente dos compromissos acadêmicos dos epidemiologistas, mas também dos compromissos com as transformações tão necessárias no nosso sistema de saúde. Após quase três décadas, podemos dizer que vem se forjando no Brasil uma epidemiologia, por um lado profundamente articulada com a evolução da disciplina no plano internacional, como deve acontecer com qualquer disciplina que persegue a sua maturidade científica e, por outro, com os pés fincados na realidade, dela procurando extrair elementos que contribuam para amenizar os problemas de saúde da sociedade.

Design of the Brazilian BCG-REVAC trial against tuberculosis: a large, simple randomized community trial to evaluate the impact on tuberculosis of BCG revaccination at school age

This paper describes the design and baseline results of a large and simple randomized controlled trial of the protection against tuberculosis of a dose of Bacillus Calmette Guerin (BCG) vaccination given to school children in a population with a high coverage of neonatal BCG (The Brazilian BCG-REVAC trial). The study started in 1996 and is a pair-matched and stratified-cluster randomized controlled trial with no placebo. The study population consists of children aged 7-14 years enrolled in 763 state schools from the cities of Salvador and Manaus, Brazil. Schools were the unit of randomization. Identifying information was collected for 354,708 school children. The final study population, after exclusions on the basis of age, BCG scar readings and absence from school on the day of the study visit, consists of 242,401 children, of whom 125,403 are in intervention schools. Follow-up relies on ascertainment of cases diagnosed at the health services and notified to the tuberculosis control program surveillance system. Blindness is guaranteed during linkage and validation of cases. Analysis is planned for the next 12 months, where efficacy will be estimated by calculating incidence of tuberculosis in the vaccine and control groups, taking into consideration the cluster design. The intervention studied, a second BCG vaccination, is widely used, although the World Health Organization does not recommend it on the basis of absence of evidence of protection or lack of protection. The results of the trial will make it possible for BCG revaccination practice to be informed by evidence. This is an example of a large simple and relatively inexpensive effectiveness trial, resulting from good collaboration between academia and health and education services enabling developing countries to define policies that are relevant for their reality.

Combined analysis of supernatant-based feeding bioassays and PCR as a first-tier screening strategy for Vip -derived activities in Bacillus thuringiensis strains effective against tropical fall armyworm

AIMS

To assess whether feeding bioassays using culture-supernatant proteins could be combined with PCR into a first-tier screening strategy for Vip3A-like genes efficient against tropical Spodoptera frugiperda.

METHODS AND RESULTS

Out of 12 Bacillus thuringiensis strains studied, the total protein concentrated from the culture supernatant of only the strain HD125 yielded a significantly increased armyworm mortality and an intense band of the predicted size for VIP3A protein in SDS-PAGE. However, PCR and sequencing data indicated Vip-like genes are ubiquitous in tropical B. thuringiensis isolates. Interestingly, the HD125 strain was also the only one displaying a single-band amplification pattern and the highest sequence identity to the reported Vip3A(a) gene.

CONCLUSIONS

Results suggest the insecticidal effectiveness of putative VIPs in B. thuringiensis isolates can be preliminarily estimated by the use of supernatant-derived total protein in feeding experiments, though only in a limited manner.

SIGNIFICANCE AND IMPACT OF THE STUDY

A simple and cost-effective first-tier screening strategy for VIP-derived activities in B. thuringiensis collections can be developed by combining PCR and feeding bioassays. Moreover, the employed primers showed to be useful as a tool for strains differentiation at DNA level, and for characterization and isolation of Vip-like genes in tropical B. thuringiensis germplasm.