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Biomedical subjects

M L Barreto

Publications and source records attributed to M L Barreto.

At least 19 recordsLinked to original sources
PubMed2007

Human allergy and geohelminth infections: a review of the literature and a proposed conceptual model to guide the investigation of possible causal associations.

Geohelminth infections and allergic disease are major public health problems and there is evidence in developing countries that they are associated. Although there is an extensive literature of the relationship between geohelminth infections and allergy, there is little consensus on whether the association is causal and if so, whether geohelminth infections may increase or decrease the risk of allergy. An explanation for the conflicting findings of epidemiological studies is that geohelminths decrease the risk of allergy in areas of high infection prevalence and increase the risk of allergy in areas of low prevalence. Chronic geohelminth infections are inversely associated with allergy and anthelmintic treatment may increase the prevalence of allergy. In this paper, we review studies that have investigated the relationship between geohelminths and allergy; discuss the relevance of prevalence and timing of geohelminth infections and propose a conceptual model to define relevant scientific questions in future human and animal studies.

Anthelmintics↗
PubMed2005

Asymptomatic giardiasis and growth in young children; a longitudinal study in Salvador, Brazil.

This study sought to assess the effect of giardiasis on growth of young children. In Salvador, northeast Brazil, 597 children initially aged 6 to 45 months were followed for a year in 1998/9, measured anthropometrically thrice, every 6 months, and monitored for diarrhoea prevalence twice weekly. Stool samples were collected and examined during the second round of anthropometry, and infected children were treated 39 days later, on average (S.D. 20 days). For each 6-month interval, the gains in z-scores of infected and uninfected children were compared, after adjustment for potential confounding factors, including longitudinal prevalence of diarrhoea. No significant difference was found for the first interval but in the second, the gain in adjusted height-for-age z-score was 0.09 less in infected than uninfected children, equivalent to a difference in height gain of 0.5 cm. The shortfall in growth was greater in children who remained free of diarrhoea, and was significantly correlated with the proportion of the second interval during which the child had remained untreated. We conclude that Giardia can impede child growth even when asymptomatic, presumably through malabsorption. This finding challenges the view that young children found to have asymptomatic giardiasis in developing countries should not be treated.

Body Height↗
PubMed2005

Growth faltering in childhood related to diarrhea: a longitudinal community based study.

OBJECTIVE: This study aimed to evaluate the association of diarrhea and acute lower respiratory tract infections (ALRI) with growth of preschool children. DESIGN: A longitudinal community-based study over a 12-month period. Children were followed up with thrice-weekly household visits for collection of morbidity data. Every 4 months (round) clinical and anthropometric examinations were performed. At baseline a questionnaire was used to collect socioeconomic family data and environmental household variables. Generalized estimating equation was used in the statistical analysis. The variations in weight-for-age or height-for-age Z-scores in each round were the dependent variables, while the main independent variables were the number of days with diarrhea and ALRI. SETTING: Serrinha, located in Northeast Brazil. SUBJECTS: In total, 487 children, aged 6-48 months at baseline, with 1-y complete follow-up. RESULTS: The number of sick days with diarrhea or ALRI was not associated with mean changes in weight-for-age Z-scores. However, the mean of height-for-age Z-scores was found to decrease in those children with 7 or more days of diarrhea (beta=-0.0472; P=0.016) but not with 1 or more days of ALRI (beta=0.0022; P=0.406) in all rounds of the follow-up period. CONCLUSION: Results of the study reinforce the concept of diarrhea burden as a major determinant of poor growth in children under 5 y of age. Actions targeted to decrease the risk factors for the occurrence of diarrhea may represent an important component of interventions aimed to ensure satisfactory child growth.

Acute Disease↗
PubMed2005

Neonatal BCG protection against tuberculosis lasts for 20 years in Brazil.

Bacille Calmette-Guérin (BCG) efficacy against pulmonary disease is highly variable; until very recently there was no evidence of protection after 10 years. In the control arm of a trial of efficacy of revaccination of schoolchildren in Brazil we found substantial protection (39%; 95%CI 9-58) of neonatal BCG against all forms of tuberculosis (TB) 15-20 years after vaccination, much longer than previously believed. This confirms recent findings from an earlier trial, and must be considered in the design of trials of new TB vaccines and in policy decisions based on assumed lack of neonatal BCG protection with time.

Adolescent↗
PubMed2004

[Impact of Chagas' infection on some demographic characteristics: results of an ecological study].

This study aimed to analyze the impact of T. cruzi infection on some demographic characteristics in the State of Bahia. It is a place where Chagas' disease is endemic in general. In the endemic areas, similar infection rates were observed in males and females. However, males, mainly those aged 30 or more, had higher mortality rates than females. Analyses were conducted on a set of secondary data from several different sources. They included prevalence of T. cruzi infection, specific mortality related to Chagas' disease, and demographic characteristics. The data were aggregated at two different levels: municipality and homogeneous micro-regions. Significant positive correlations were observed between prevalence of T. cruzi infection and mortality rates. These indicators, in turn, were correlated with the proportion of widows and widowers in the population. Findings were higher for widows. In areas where prevalence of T. cruzi infection was 15% or greater, there were 22% more widows as compared to infection free areas. Places with high prevalence presented some skew in the age structure, and there was a consistent decrease in the proportion of males in the 35-44 age group. A possible confounding effect of migration on these finding was not demonstrated.

English Abstract↗
PubMed2004

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.

Adolescent↗
PubMed2004

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.

Adolescent↗
PubMed2003

[Schistosomiasis mansoni in Bahia, Brazil: historical trends and control measures].

In order to aid the development of new approaches to schistosomiasis control, changes were analyzed in prevalence at the county level in the State of Bahia from the 1950s to the 1990s, as were determinants and the effect of community-based chemotherapy. In general, no substantial changes were observed in the basic pattern of spatial distribution of the prevalence of infection. However, during the period studied, there was an overall reduction in prevalence from 15.6% to 9.5% and an increase in prevalence rates in some counties from the western, southeastern, and northern areas of Bahia, indicative of new transmission areas. The effect of mass chemotherapy was analyzed. In the Paraguaçu Basin, where this control measure was used on a large scale, there was a reduction in prevalence similar to areas where this measure was not used. Correlation and regression analysis also failed to show links between mass chemotherapy and long term reduction in prevalence. The most powerful variables to explain these changes were those related with population dynamics. These findings strongly suggest that the reduction in prevalence observed in some areas of the State must be attributed to factors related with the spatial organization of this territory, causing a general decrease in the transmission rate, secondary to mass chemotherapy. At the same time, the incomplete form and the spatial inequalities that characterized the urbanization process created favorable conditions for the spread of schistosomiasis mansoni and the establishment of new foci.

English Abstract↗
PubMed2003

[A popular concept of schistosomiasis mansoni: modes of transmission and prevention in the perspective of gender differences].

This is a study on popular ideas, beliefs and practices concerning the transmission and prevention of parasitic diseases, specifically schistosomiasis mansoni. The author explored the existence of a popular belief system within the health care system, combining elements from biomedicine and folk medicine for the understanding and management of the health/disease phenomenon. The study describes the differences in perception of morbidity and gender among the interviewees. Finally, the study presents popular discourse on parasitic diseases and discusses difficulties with control measures. It considers the contradiction between cultural values and habits and conventional control measures, critically assessing the lack of precision in health education measures under government prevention programs.

English Abstract↗
PubMed2003

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.

Brazil↗
PubMed2003

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.

Animals↗
PubMed2003

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.

Adolescent↗
PubMed2003

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.

Adolescent↗
PubMed2002

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.

Animals↗