Cláudio Santos Ferreira

Tendência secular das parasitoses intestinais na infância na cidade de São Paulo (1984-1996)

OBJETIVO: Estimar a prevalencia e a distribuicao social das parasitoses intestinais na infância, estabelecer a tendencia secular dessas enfermidades e analisar sua determinacao, com base em dois inqueritos domiciliares, realizados na cidade de Sao Paulo, SP, em 1984/85 e 1995/96. METODOS: Os inqueritos estudaram amostras probabilisticas da populacao residente na cidade com idades entre zero e 59 meses (1.016 em 1984/85 e 1.280 em 1995/96). Amostras de fezes foram coletadas nos dois inqueritos e submetidas a exame parasitologico pela tecnica de sedimentacao, realizando-se leituras de preparacoes simples e de preparacoes coradas com lugol para exame de cistos de protozoarios. O estudo da distribuicao social das parasitoses levou em conta tercis da renda familiar per capita em cada um dos inqueritos. A estrategia analitica para estudar os determinantes da evolucao da prevalencia das parasitoses na populacao empregou modelos hierarquicos de causalidade, analises multivariadas de regressao e procedimentos analogos aos utilizados para calcular riscos atribuiveis populacionais. RESULTADOS/CONCLUSOES: Houve entre os inqueritos reducoes expressivas na prevalencia das parasitoses em geral (de 30,9% para 10,7%), das helmintoses (22,3% para 4,8%), da giardiase (14,5% para 5,5%) e do poliparasitismo intestinal (13,1% para 0,5%). Embora declinios intensos tenham sido observados em todos os estratos sociais, manteve-se inalterada no periodo a forte relacao inversa entre nivel de renda e ocorrencia de parasitismo. Mudancas positivas em determinantes distais (renda familiar e escolaridade materna) e intermediarios (moradia, saneamento do meio e acesso a servicos de saude) das helmintoses, justificaram parte substancial da reducao de sua prevalencia. A reducao da giardiase foi atribuida a melhorias na escolaridade materna e nas condicoes de moradia e saneamento. A duplicacao da frequencia a creches refreou o declinio da giardiase.OBJETIVO: Estimar a prevalencia e a distribuicao social das parasitoses intestinais na infância, estabelecer a tendencia secular dessas enfermidades e analisar sua determinacao, com base em dois inqueritos domiciliares, realizados na cidade de Sao Paulo, SP, em 1984/85 e 1995/96. METODOS: Os inqueritos estudaram amostras probabilisticas da populacao residente na cidade com idades entre zero e 59 meses (1.016 em 1984/85 e 1.280 em 1995/96). Amostras de fezes foram coletadas nos dois inqueritos e submetidas a exame parasitologico pela tecnica de sedimentacao, realizando-se leituras de preparacoes simples e de preparacoes coradas com lugol para exame de cistos de protozoarios. O estudo da distribuicao social das parasitoses levou em conta tercis da renda familiar per capita em cada um dos inqueritos. A estrategia analitica para estudar os determinantes da evolucao da prevalencia das parasitoses na populacao empregou modelos hierarquicos de causalidade, analises multivariadas de regressao e procedimentos analogos aos utilizados para calcular riscos atribuiveis populacionais. RESULTADOS/CONCLUSOES: Houve entre os inqueritos reducoes expressivas na prevalencia das parasitoses em geral (de 30,9% para 10,7%), das helmintoses (22,3% para 4,8%), da giardiase (14,5% para 5,5%) e do poliparasitismo intestinal (13,1% para 0,5%). Embora declinios intensos tenham sido observados em todos os estratos sociais, manteve-se inalterada no periodo a forte relacao inversa entre nivel de renda e ocorrencia de parasitismo. Mudancas positivas em determinantes distais (renda familiar e escolaridade materna) e intermediarios (moradia, saneamento do meio e acesso a servicos de saude) das helmintoses, justificaram parte substancial da reducao de sua prevalencia. A reducao da giardiase foi atribuida a melhorias na escolaridade materna e nas condicoes de moradia e saneamento. A duplicacao da frequencia a creches refreou o declinio da giardiase.

Intestinal parasitic infections in young children in São Paulo, Brazil: prevalences, temporal trends and associations with physical growth

Abstract The prevalences of intestinal parasitic infections were investigated, between 1995 and 1996, in a household-based sample of 1044 children aged <5 years who lived in the city of São Paulo, Brazil. Only 10.7% of the children were infected, the most prevalent parasites being Giardia duodenalis (5.5%), Ascaris lumbricoides (4.4%) and Trichuris trichiura (1.0%). A comparison between these data and results from two previous population-based surveys, completed in São Paulo in 1974 and 1985, revealed a dramatic decrease in the prevalence of intestinal helminths in this age-group, with less marked changes in the prevalence of Giardia, over the two past decades. Despite the low prevalence of malnutrition (2.4% of stunting and 0.6% of wasting) and intestinal parasites in this population, there was a significant association (P=0.05, after controlling for potential confounding variables) between helminth (but not Giardia) infection and height. The helminth-infected children had a mean height-for-age z-score of–0.412 [95% confidence interval (CI)=–0.637––0.186], compared with one of 0.015 (CI=–0.049-0.079) for the non-infected children. No significant relationship between intestinal parasitic infection and childrens weight was detected. In conclusion, a small but significant negative relationship between intestinal helminthic infections and childrens growth was detected in an urban environment with low prevalences of both intestinal parasitic infection and malnutrition.

Intestinal parasites among Karitiana Indians from Rondônia State, Brazil

Gravity sedimentation parasitological examinations were performed in stool samples from 111 Karitiana Indians from Rondônia State, Brazilian Amazon Basin. Intestinal parasites were found in 43 samples (38.7%). Ascaris lumbricoides was the most prevalent helminth species (18.9%). Egg counts in samples positive for Ascaris suggested an overdispersed distribution of worm burdens in the host population. Age-distribution pattern of intestinal parasites among Karitiana Indians was found to be rather unusual: the highest prevalence (60.0%) was detected in the 12- to 16-year-old age group.

Pasteurization of human milk to prevent transmission of Chagas disease

Although admittedly transmission of Trypanosoma cruzi infection through breastfeeding is a rare event, it involves serious risks. To test the effectiveness of pasteurization in preventing this mode of infection, three sets of samples of human milk were tested: a - contaminated with T. cruzi and pasteurized; b - contaminated with T. cruzi and non-pasteurized; c - non-contaminated and pasteurized. Samples from all sets were orally and intraperitoneally administered to 90 BALB/c mice. The animals inoculated with contaminated, non-pasteurized samples, got the infection. Controls and the animals inoculated with contaminated and pasteurized milk were not infected. The hypothesis was accepted that pasteurization inactivates T. cruzi trypomastigotes.

Malaria seroepidemiology: comparison between indirect fluorescent antibody test and enzyme immunoassay using bloodspot eluates

Blood sampling on filter paper is a current practice in malaria seroepidemiological studies by indirect fluorescent antibody test (IFAT). There is, however, scant comparative information about the use of bloodspot eluates for detection of malarial IgG antibodies simultaneously by IFAT and enzyme immunoassay (ELISA). Here we report data obtained by both serological methods done on 219 bloodspot eluate samples collected in a rural community in Brazilian Amazon Basin (Alto Paraíso, Ariquemes municipality) where malaria is endemic. Plasmodium falciparum and P. vivax thick smear antigens were used in the IFAT; a detergent-soluble P. falciparum antigen was prepared for ELISA. Substantial agreement of results (Kappa coefficient k = 0.686) was observed when P. falciparum antigen was used in both tests, and IFAT titers were found to be strongly correlated to ELISA antibody units (Spearman correlation coefficient rs = 0.818, p < 0.001). Only moderate agreement (k = 0.467) between IFAT with P. vivax antigen and ELISA with P. falciparum antigen was observed. Spearman correlation coefficient value between quantitative results (IFAT titers and ELISA antibody units) in this case was numerically lower (rs = 0.540, p < 0.0001). Our results suggest that, with P. falciparum antigen, both IFAT and ELISA performed on bloodspot eluates are equivalent for seroepidemiological purposes.

Observações sobre o TESA blot no diagnóstico sorológico da doença de Chagas

TESA blot was compared with indirect hemagglutination, indirect immunofluorescence and ELISA tests. In sera from 30 participants infected with Trypanosoma cruzi, and in 30 non infected the four techniques produced entirely equivalent results, all positive and all negative, respectively. In cases admitted to be inconclusive or in visceral leishmaniasis, frequent false positives were detected. However, TESA blot contributed with the least proportion of them.

Elevada porcentagem de blastocistose em escolares de São Paulo, SP

As a part of medical assistance activities, parasitological examination of fecal samples from 227 school children from a public institution of São Paulo (SP) revealed a rather high proportion of results positive for Blastocystis hominis. Other protozoan and worm species were markedly scarcer, a peculiar situation according to our judgement. It is acknowledged that blastocystosis is still largely an indefinite and controversial subject, which deserves adequate analysis to avoid drawbacks in the sphere of action of public health and general medical assistance.

Microwave treatment of human milk to prevent transmission of Chagas disease

It is recognized that breast feeding is an alternative means of transmission of Chagas disease. However, thermal treatment of milk can prevent this occurrence. As domestic microwave ovens are becoming commonplace, the efficacy of microwave thermal treatment in inactivating Trypanosoma cruzi trypomastigotes in human milk was tested. Human milk samples infected with T. cruzi trypomastigotes (Y strain) from laboratory-infected mice, were heated to 63 degrees C in a domestic microwave oven (2,450 MHz, 700 W). Microscopical and serological examinations demonstrated that none of the animals inoculated orally or intraperitoneally with infected milk which had been treated, got the infection, while those inoculated with untreated, infected milk, became infected. It was concluded that the simple treatment prescribed, which can easily be done at home, was effective in inactivating T. cruzi trypomastigotes contained in human milk.

Eficiência do diagnóstico coproscópico de Schistosoma mansoni em fezes prensadas

The control of schistosomiasis depends mostly upon the sensitivity of stool examinations. We used both the Kato-Katz technique and the compression of samples between the slide and a polypropylene cover glass, according to Ferreira. Out of 1,282 samples collected between 1998 and 2000 in the Palha District, Municipality of Bananal, São Paulo State, Brazil, 105 (8.2 %) were positive. The first and second methods revealed 90 (7%) and 88 (6.9 %) positive cases, respectively. According to the kappa statistic, both methods were in agreement. In Bananal, the proportion of positive cases and egg per gram (epg) values are low, which calls for the examination of larger than usual volumes of feces. The viability of Schistosoma mansoni eggs can also be checked when using the second method, which dispenses with glycerin solution, measuring plates and sieves. The latter cause a further loss of precision in epg determinations.

Rapid epidemiologic assessment of breastfeeding practices: probit analysis of current status data.

We describe the use of probit analysis to estimate breastfeeding indicators from current status epidemiological data. A health centre-based sample of 2411 children aged 0-1 year was investigated in Santo Andre, a large town in the Metropolitan Area of Sao Paulo, southeastern Brazil. Mothers were interviewed during routine pediatric consultations and asked about their current infant feeding practices. Probit regressions were calculated by a public-domain microcomputer programme written by one of us. The median duration of total (i.e. exclusive plus partial) breastfeeding in this childrens sample, estimated as 108.8 days (95 per cent confidence interval: 95.5-123.2 days), is close to that recently reported in the city of Sao Paulo and nearby towns. However, the median duration of exclusive breastfeeding (28.9 days, 95 per cent CI: 17.9-38.3 days) is rather short when compared to recent estimates from this same region. Despite the nationwide efforts for promotion of exclusive breastfeeding, only 14 per cent (95 per cent CI: 12.3-17 per cent) of the infants were still being exclusively breastfed by 120 days of age. Therefore, a key feature of breastfeeding practices in this population sample, namely, the early introduction of supplementary foods, was identified by using simplified methods of data collection and analysis. This communication suggests that probit analysis of current status data may be further explored as a method for rapid epidemiologic assessment of breastfeeding practices.