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Between November 1993 and April 1994, our physicians' team interviewed and took blood samples of 631 prisoners randomly drawn from the largest prison of South America, which counted about 4700 inmates at that time. The interview consisted of questions related to risk behaviour for HIV infection, and the subjects were asked to provide blood for serological tests for HIV, hepatitis C and syphilis. Our main purpose was to investigate the relationship between HCV and injecting drug use as related to HIV seropositivity. Participation in the study was voluntary and confidentiality was guaranteed. Overall prevalences found were as follows: HIV: 16% (95% confidence interval (CI): 13-19%); HCV: 34% (95% CI: 30-38%), and syphilis: 18% (95% CI: 15-21%). Acknowledged use of ever injecting drug was 22% and no other parenteral risk was reported. Our results, as compared with other studies in the same prison, suggest that HIV prevalence has been stable in recent years, and that the major risk factor for HIV infection in this population is parenteral exposure by injecting drug use.

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This work was designed to evaluate the role of intestinal parasites on nutritional status in three rural areas of Brazil. A total of 520 children aged 1-12 years were studied through a questionnaire concerning housing, socio-economic conditions and a 24-h food intake recall. Measurements of weight and height were also performed, and three stool samples were collected on consecutive days for parasitological analysis. Scores of the standard deviation (z-scores) for the weight-for-height and height-for-age were used to characterise the growth profile. A high prevalence of intestinal parasites was detected, with Giardia lamblia (44%), Endolimax nana (43%), Ascaris lumbricoides (41%) and Trichuris trichiura (40%) being the most prevalent. Eleven per cent of the children were classified as showing stunting. Inadequate daily caloric intake was observed in 78% of the population and the proportion of those with inadequate protein intake was 34%. Logistic regression analysis was employed for the multivariate study. Stunting was significantly associated with estimators of low economic income, inadequate protein intake and polyparasitism, especially the association between Ascaris lumbricoides and Trichuris trichiura.

PIP: This study was designed to assess the association between stunting and helminthic infections by studying children aged 1-12 years living in a rural area near Sao Paolo, Brazil. A total of 520 children were studied through a questionnaire concerning housing, socioeconomic conditions and a 24-hour food intake recall. Measurement of weight and height were also performed, and three stool samples were collected on consecutive days for parasitological analysis. The study has demonstrated a positive association between intestinal parasites and stunting in children. Intestinal parasites were present in 79% and stunting in 11.5% of children from the sample. 56.7% of the children with stunting were between 5 and 12 years of age, which justified the unusual inclusion of children above 5 years of age. The most prevalent intestinal parasites detected were Giardia lamblia (44%), Endolimax nana (43%), Ascaris lumbricoides (41%), and Trichuris trichiura (40%). In the study, no children reported diarrhea and/or fever. Nevertheless, the mechanism of parasitic infections includes anorexia, type of food intake, intestinal villus damage, competition for nutrients, facilitation of bacterial colonization, increase in energy requirements, decrease in hepatic protein synthesis, protein-losing enteropathy, and blood loss. Inadequate daily caloric intake was observed in 78% of the population, and the proportion of those with inadequate protein intake was 34%. Stunting was significantly associated with estimators of low economic income, inadequate protein intake and polyparasitism.

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When directly transmitted infectious diseases are modeled assuming an everlasting induced immunity (and constant contact rate), there are well-established formulas to deal with, which is not true if we include the loss of induced immunity. In general, the immunity induced by the disease is everlasting. We propose a model considering the loss of immunity and present methods for the estimation of two epidemiological parameters: the force of infection and the basic reproduction ratio. We also analyze the effects of the loss of immunity on these parameters. Based on these results, we concluded that reinfection can play an important role in highly vaccinated populations.

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BACKGROUND: In 1992 a major vaccination strategy against measles-mumps-rubella was introduced in the State of Saão Paulo, Brazil. This strategy was based on mathematical models and comprised a pulse vaccination covering all children aged 1-10 years, followed by the inclusion of this vaccine in the routine calendar at 15 months of age. The present work reports the evaluation of the efficacy of this mixed vaccination strategy. METHODS: A rubella seroprevalence survey was carried out immediately and one year after the campaign, comprising 4953 children aged 1-15 years. RESULTS: We show that average rubella seroprevalence increased from 0.40 to 0.97 and that the reported number of congenital rubella syndrome (CRS) cases dropped dramatically. CONCLUSIONS: The mixed vaccination strategy adopted against rubella has proved to be very effective in reducing the number of CRS cases in São Paulo.

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The sensitivity and specificity of salivary rubella antibody detection was investigated using samples collected from 301 children after a mass vaccination campaign in the state of São Paulo, Brazil. Saliva samples were collected by 2 different methods: directly dribbling into a container or using a commercial collecting device. Corresponding finger-prick blood samples were collected on filter paper. Rubella specific immunoglobulin G (IgG) was measured in saliva by antibody capture radioimmunoassay and in blood samples by indirect enzyme-linked immunosorbent assay. The detection of salivary rubella specific IgG showed good correlation with the detection of rubella antibody in the blood samples. For both collecting techniques the predictive value for a positive saliva test was > 99% compared with the results from the blood tests. However, the predictive value for a negative saliva test was only 58.3% for a dribbled sample, compared to 100% for saliva collected using the commercial device. Moreover, collecting saliva by dribbling from children less than 4 years old was difficult. The detection of rubella specific IgG in saliva collected using a commercial device proved to be sensitive and specific in this epidemiological study, encouraging its more widespread application as a means of surveillance after mass vaccination.

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A rubella serological survey of 476 individuals selected by cluster sampling technique from Caieiras, a small town located in the outskirts of São Paulo city, southeastern Brazil, was carried out over the period November 1990-January 1991. The aim of the study was to characterize rubella epidemiology in a representative non-immunized community in south east Brazil. The survey comprised a seroprevalence study, stratified by age (0-40 years) and a seroconversion study of rubella vaccine in non-infected children below 2 years of age. Mathematical techniques were applied to resultant data sets to determine the age dependent rates of decay in the proportion of individuals with maternally derived antibodies, vaccine seroconversion, and infection of susceptibles, termed the force of infection, and to estimate the average age at first infection.

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