Epidemiology is more than discourse: critical thoughts from Latin America.
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El Salvador↗
Biomedical subjects
M L Barreto
Publications and source records attributed to M L Barreto.
Skin test reactivity to mycobacterial antigens parallels the phylogenetic structure of their genus.
SETTING: City of Manaus, Amazonas, Brazil. OBJECTIVE: To explore the relationship between positivity to tuberculin and other environmental mycobacteria sensitins, according to a range of criteria and presence of BCG scar. DESIGN: Dual skin testing with tuberculin and four mycobacterial sensitins, and BCG scar recording of 1070 schoolchildren aged 7-14. Four criteria for positivity were used: simple and dominant, with 5 and 10 mm cut-off points. RESULTS: The standardised prevalence of reactions > or = 5 mm for BCG scar negative children was 58.3% for Mycobacterium avium, 54.2% for M. scrofulaceum, 26.8% for M. fortuitum, 17.9% for M. tuberculosis and 7.6% for M. kansasii. Correlations between tuberculin and each sensitin, for BCG scar negative children, were 0.47 for M. avium, 0.53 for M. scrofulaceum, 0.60 for M. kansasii and 0.22 for M. fortuitum (all with P < 0.01). BCG effect was particularly significant for tuberculin (odds ratio = 3.44 for reactions > or = 5 mm, P < 0.001) and influenced the balance between dominant/non-dominant reactions for all sensitins. CONCLUSION: The correlation between tuberculin and each sensitin confirmed the separation of the rapidly (M. fortuitum) and slowly growing mycobacteria (M. tuberculosis, M. avium, M. scrofulaceum and M. kansasii). The influence of BCG on tuberculin reactions was more marked than on other mycobacterial sensitins.
Adolescent↗
Sensitivity and specificity of BCG scar reading in Brazil.
In a cross sectional survey within a community trial of BCG efficacy evaluation in Brazil, trained teams inspected children's upper arms and obtained information on BCG vaccination from guardian letters and vaccination cards. Nurses re-examined the sub-sample of children blindly. High agreement was found between the two scar readings (Kappa = 0.839). High sensitivity and low specificity was observed when guardian or card information was the gold standard. Sensitivity remained high when guardian and card information agreed. When disagreement occurred, sensitivity remained high and specificity was very low. BCG scar is a good indicator of BCG vaccination.
BCG Vaccine↗
Upward trend in the rate of detection of new cases of leprosy in the State of Bahia, Brazil.
BACKGROUND: The worldwide fall in the rate of detection of new cases of leprosy has been partly attributed to the introduction of multidrug therapy and other improvements in control programs. However, the rate of detection of new cases has not decreased in Brazil. METHODS: An analysis was made of the temporal distribution of 18,872 newly reported leprosy cases in Bahia, Brazil, from 1974 to 1997. Population denominators for the annual detection rate were obtained from population estimates based on the national census. Trends were presented by sex, date of birth, date of diagnosis, date of release, clinical form and by residence in areas which had notified cases in the 5 years prior to the rise in detection rate. RESULTS: There was a marked increase in the new case detection rate (NCDR) in the State of Bahia, from 0.19 to 1.43 cases per 10,000 inhabitants during the study period, an increment of nearly 7% to 8% per year. This increase was also observed in people aged 14 years and younger. During this period tuberculoid and indeterminate forms have become predominant among women and younger people. The average age of male cases has shifted toward younger ages. CONCLUSIONS: We interpret this pattern to mean that the increase in NCDR reflects a real increase in incidence of leprosy, whether or not accompanied by improved detection.
Adolescent↗
Lower hookworm incidence, prevalence, and intensity of infection in children with a Bacillus Calmette-Guérin vaccination scar.
Bacillus Calmette-Guérin (BCG), the most common vaccine worldwide, has broad effects on the immune system. Hookworm infections are a major source of morbidity. In response to a preliminary report of BCG vaccination protection against nematodes in human immunodeficiency virus-infected adults, data from an ongoing prospective study were analyzed to determine the intensity (eggs per gram of stool), prevalence, and incidence of different helminths in children with and without a BCG vaccination scar. Adjusted prevalence and incidence ratios were estimated by using logistic regression. Children with a BCG vaccination scar were found to have statistically significantly lower hookworm prevalence (41%), incidence (37%), and mean egg counts (39%), after controlling for age, sex, and socioeconomic factors. There was no BCG association with incidence, prevalence, or intensity of infection with Schistosoma mansoni, Ascaris lumbricoides, or Trichuris trichiura. Such protection would have implications for public health and for research on mechanisms behind human immunological responses to hookworm.
Adolescent↗
Outbreak of aseptic meningitis associated with mass vaccination with a urabe-containing measles-mumps-rubella vaccine: implications for immunization programs.
A mass immunization campaign with a Urabe-containing measles-mumps-rubella vaccine was carried out in 1997 in the city of Salvador, northeastern Brazil, with a target population of children aged 1-11 years. There was an outbreak of aseptic meningitis following the mass campaign. Cases of aseptic meningitis were ascertained through data collected from the records of children admitted to the local referral hospital for infectious diseases between March and October of 1997, using previously defined eligibility criteria. Vaccination histories were obtained through home visits or telephone calls. Eighty-seven cases fulfilled the study criteria. Of those, 58 cases were diagnosed after the vaccination campaign. An elevated risk of aseptic meningitis was observed 3 weeks after Brazil's national vaccination day compared with the risk in the prevaccination period (relative risk = 14.3; 95% confidence interval: 7.9, 25.7). This result was confirmed by a case series analysis (relative risk = 30.4; 95% confidence interval: 11.5, 80.8). The estimated risk of aseptic meningitis was 1 in 14,000 doses. This study confirms a link between measles-mumps-rubella vaccination and aseptic meningitis. The authors discuss the implications of this for the organization and planning of mass immunization campaigns.
Brazil↗
Questionnaire approach to diagnosis in developing countries.
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Child↗
Measuring the burden of common morbidities: sampling disease experience versus continuous surveillance.
Longitudinal prevalence, the proportion of all days of observation that a given individual manifests symptoms of illness, is a measure of disease frequency that is easy to generate from daily morbidity data and has been shown to be strongly related to subsequent health outcome. It is hypothesized that this measure could be derived using a representative sample of days of observation rather than continuous surveillance. The authors use 1990-1991 data from a Brazilian supplementation trial comprising a year's daily records of the occurrence of diarrhea, fever, and cough in 906 children under 5 years of age to examine how many days of morbidity data need to be observed to rank subjects into quintiles of illness frequency. Systematic samples of the full data set, based on every 2nd, 3rd, 5th, 10th, 15th, 20th, and 30th day of data, are compared with the continuous record. For diarrhea and fever, estimates based on less than 72 days of observation result in over one fourth of individuals who should have been in the extreme quintiles of the morbidity distribution being misclassified, and over one fifth of all subjects appear (falsely) to suffer no morbidity. Estimates of longitudinal prevalence should be based on at least 72 days of observation.
Brazil↗
Schistosoma mansoni infection and nutritional status in schoolchildren: a randomized, double-blind trial in northeastern Brazil.
Brazilian schoolchildren with mild- to moderate-intensity schistosome infections (<400 Schistosoma mansoni eggs/g stool) were randomly allocated to a treatment (oxamniquine) or placebo group in a double-blind fashion. Anthropometric measurements were made at baseline, 6 mo, and 1 y for 353 students. At baseline, the groups were not significantly different with respect to nutritional status or selected socioeconomic and biological characteristics, including anthropometric measures. One year later, significant differences were noted only in the nutritional status of boys treated for schistosome infection. Treated boys had greater measurements for weight, triceps skinfold thickness, midarm circumference, arm muscle area, and body mass index than untreated boys. They also showed significant increases over the year in weight, height, midarm circumference, and body mass index. The rates of improvement in weight and height were more accelerated in the first 6 mo after therapy than the last. These results indicate that, at least in boys, chronic S. mansoni infection at any intensity is detrimental to short-term growth and development.
Adolescent↗
[Paternity in the perspective of a group of fathers].
Looking upon occidental silence which involves the paternity, we performed this research with the intention to conceive some associated aspects: the family role, birth of son expectation and father social role. For that, 7 fathers have been interviewed with ages between 21 and 45 years. This study allowed us observed that the paternity of the interviewed fathers is experienced by the father-son relationship preoccupation, kids education and the constant search of ways to experience the paternity as a form to be near of the kids and the wife.
Adult↗
[Nutritional status of pre-school children of the semi-arid region of Bahia (Brazil): II--Vitamin A deficiency].
A survey of 754 preschool children was undertaken in the urban areas of seven small towns of the semi-arid region of Bahia, Northeastern Brazil, to determine the prevalence of vitamin A deficiency, as well as its association with variables such as a age, family income, mother's schooling and dietary adequacy in vitamin A. Protein energy malnutrition and anemia were also studied and are reported separately. The clinical ophthalmological examination did not reveal any signs or symptoms of xerophthalmia amongst these children. In 563 children serum retinol was determined and the average value found was 20.3 micrograms/dl (SD = 10.8 micrograms/dl); the prevalence of deficient serum retinol (below 10.0 micrograms/dl) was of 15.3%. In all 7 localities studied, the prevalence of deficient retinol levels was above 5.0%, the criterion recommended by WHO for considering it a Public Health Problem. The distribution of serum retinol was similar between the sexes, but there was an age trend: the prevalence of deficient and low levels decreased with age. There was no association between deficient serum retinol and family income per capita or mother's education. Results from the 24 h food consumption survey revealed that only 8% of children had an adequate intake of vitamin A through the diet; 66% received less than 1/2 and 35% less than 1/4 of the recommended daily intake of vitamin A. Vitamin A deficiency should be considered a Public Health Problem in the region due to the high prevalence of deficient levels of serum retinol as well as the large dietary inadequacy.
Age Factors↗
Gender differences in growth of school-aged children with schistosomiasis and geohelminth infection.
Light or moderate intensity infection with Schistosoma mansoni may contribute to growth deficits. We report on the effects of treatment for S. mansoni on growth and development in Brazilian schoolchildren. Anthropometric measurements were taken from 539 S. mansoni-infected children and their age- and sex-matched egg-negative controls between the ages of 7 and 15 years. The children as a whole exhibited chronic malnutrition, with growth retardation in height evident in 21% of the population. Infected children, however, were significantly smaller in height, weight, mid upper arm circumference (UAC), tricep skinfold (TSF), and subscapular skinfold (SSF) measurements than control children (P < 0.05). These differences were due primarily to a greater disparity between infected and egg-negative girls in height (P < 0.01), weight (P = 0.01), UAC (P = 0.O2), and TSF (P < 0.01). Nevertheless, girls demonstrated a better level of development and nutrition compared with boys. While infected boys were shorter and weighed less than controls, these differences were not significant. Growth and development in girls was negatively correlated with intensity of infection. Coinfection with S. mansoni and Trichuris appeared to act synergistically in the development of malnutrition.
Adolescent↗
[Nutritional and feeding status of preschool children in the semi-arid region of Bahia (Brazil): I. Anthropometric assessment].
A survey of 754 preschool children was undertaken in the urban areas of seven small towns of the semi-arid region of Bahia, Northeast Brazil. The study set out to determine the prevalence of weight and height deficits, as well as to correlate them with variables such as age, family income, mother's schooling and food consumption. A prevalence of 22.9% of Height for Age (HA) below -2.0 SD was found (stunting) and prevalence of 19.1% and 3.6% were determined, respectively for Weight for Age (WA) and Weight for Height (WH) below -2.0 SD (wasting). Regarding food consumption, only 6.8% of the children received a diet with an adequate energy supply for their age group in the previous day. There was a close association between inadequate HA and WA and family income per capita (p = 0.001 and p = 0.000, respectively). Children from families with income < 1/4 of the minimum wage per capita had twice the chance of being malnourished as compared with those from the > or = 1/2 minimum wage per capita stratum. The children included in this study showed prevalences of inadequate WH and WA significantly higher than those found in a national survey conducted in the same period (p = 0.047 and p = 0.000 respectively). This fact is surprising since in the last decade important reductions in child malnutrition and mortality were reported in the country as a whole; this may indicate that children from this region probably were not benefitted in the same way as the rest of the Brazilian child population.
Age Factors↗
Effect of vitamin A supplementation on diarrhoea and acute lower-respiratory-tract infections in young children in Brazil.
A beneficial effect of periodic vitamin A supplementation on childhood mortality has been demonstrated, but the effect on morbidity is less clear. We investigated the effect of vitamin A supplementation on diarrhoea and acute lower-respiratory-tract infections (ALRI) in children from northeastern Brazil in a randomised, double-blind, placebo-controlled community trial. 1240 children aged 6-48 months were assigned vitamin A or placebo every 4 months for 1 year. They were followed up at home three times a week, and data about the occurrence and severity of diarrhoea and ALRI were collected. Any child with cough and respiratory rate above 40 breaths per min was visited by a paediatrician. The overall incidence of diarrhoea episodes was significantly lower in the vitamin-A-supplemented group than in the placebo group (18.42 vs 19.58 x 10(-3) child-days; rate ratio 0.94 [95% Cl 0.90-0.98]). The benefit of supplementation was greater as regards severe episodes of diarrhoea; the incidence was 20% lower in the vitamin A group than in the placebo group (rate ratio 0.80 [0.65-0.98]). With the standard definition of diarrhoea (> or = 3 liquid or semi-liquid stools in 24 h) the effect of vitamin A on mean daily prevalence did not reach significance, but as the definition of diarrhoea was made more stringent (increasing number of stools per day), a significant benefit became apparent, reaching for diarrhoea with 6 or more liquid or semi-liquid stools in 24 h a 23% lower prevalence. We found no effect of vitamin A supplementation on the incidence of ALRI. The reduction in severity of diarrhoea may be the most important factor in the lowering of mortality by vitamin A supplementation.
Acute Disease↗
The dot map as an epidemiological tool: a case study of Schistosoma mansoni infection in an urban setting.
In this paper dot maps are used as an epidemiological tool to describe the spatial patterns of cases, non-cases and some relevant risk factors associated with the occurrence of Schistosoma mansoni infection in an urban environment. The study was carried out in Santo Antonio de Jesus, a town in north-east Brazil with a population of around 45,000 inhabitants. The survey was targeted at all children aged between 12 years 8 months and 14 years 11 months who were living in the town at the time of the survey. An extensive questionnaire was used to collect information on each child and on family and household conditions; stool samples were also taken for quantitative examination. A computerized digitizer was used on a map (scale 1:4000) to create x and y coordinates for each child's household. The result was matched with individual data from the questionnaires and the stool examination. From this data base it was possible, by using a statistical package, to make epidemiological analyses and by using the statistical package associated with a geocartographic system package it was possible to dot plot selected values of defined variables. These techniques substantiated the findings on the risk factors at a local level and, as a consequence, improve our ability to define targeted actions towards local control of schistosomiasis.
Adolescent↗
Use of risk factors obtained by questionnaires in the screening for Schistosoma mansoni infection.
Several social, environmental, and behavioral variables shown to be strongly associated with the level of Schistosoma mansoni infection were evaluated regarding their power to discriminate infected from noninfected children. Emphasis was placed on the identification of infected persons with high egg counts, who are at risk of developing the severe clinical forms of the disease. Data were collected in a survey carried out in a town (Santo Antonio de Jesus) in northeastern Brazil. The sample consisted of all children 12-14 years old living in the town. An extensive questionnaire was used to collect information on each child and on family and household conditions. Stool samples were taken for quantitative examination. The prevalence of S. mansoni infection was 31.0%. The risk factors were first analyzed one-by-one and then aggregated using logistic models. From the models, individual probabilities of being infected were estimated. The results were then used to produce relative operating characteristics curves. The model with highest discriminative power was that which included five risk factors, namely migratory status and four others related to water-contact activities. The ability to discriminate increased with an increase in the level of egg excretion. The conclusion is that the development of short questionnaires for large-scale screening for S. mansoni infection in endemic areas is realistic.
Adolescent↗
Geographical and socioeconomic factors relating to the distribution of Schistosoma mansoni infection in an urban area of north-east Brazil.
A study was carried out in Santo Antonio de Jesus, a town in Bahia State, north-east Brazil, to determine the relationship between various biological, socioeconomic, behavioural, and geographical factors and the prevalence and intensity of Schistosoma mansoni infection. The town's population was around 45,000 and the study was targeted at all children born in 1970-71 who were living in the town at the time of the survey (August-November 1984). An extensive questionnaire was used to collect information on each child and on family and household conditions; samples of stools were also taken for examination (Kato-Katz method). A survey of water snails was also carried out and information on the distribution of their breeding sites was plotted on a map of the area. The overall prevalence of S. mansoni infection was 31.0%. Several variables that reflected different aspects of the population's way of life were strongly associated with the prevalence and the intensity of infection. Some of the findings are valuable for understanding the mechanisms involved in the occurrence of schistosomiasis and its distribution in urban locations as well as for defining high-risk groups, all of which are important for planning control strategies.
Adolescent↗
[Cause vs. prediction: history of bathing in rivers as a risk factor and predictor of infection by Schistosoma mansoni].
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Adolescent↗