RESUMO

The Trichuris trichiura worm burdens of 23 children living in a Place-of-Safety in Kingston, Jamaica, were assessed by stool collection for more than five days after treatment with mebendazole. This procedure was repeated after a seven-month period of natural re-infection. For both collections the maximum rate of worm expulsion was achieved on the fourth day after starting treatment. The worm population distributions were overdispersed and well described by the negative binomial probability model (k = 0.29) in each case. For any one individual, the number of worms passed on the first expulsion was unrelated, absolutely or relatively, to the number passed on the second. These data suggest that: knowledge of the time dependency of helminth expulsion is essential for the accurate estimation of worm burdens by this method; populations of Trichuris are more highly aggregated than those of Ascaris and may thus be more susceptible to control by selective rather than random chemotherapy; and the inherent predisposition of hosts to infection may be of minor importance in determining the distribution of worms in the population-heavily infected hosts appear no more or less likely to acquire large worm burdens on subsequent exposures.

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RESUMO

PIP: The value of prolonged breast-feeding in the prophylaxis of atopic disease was confirmed by Dr. Saarin and colleagues, and Matthew et al. have suggested that antigen avoidance by prolonged breast-feeding could help prevent asthma. Prolonged breast-feeding is more prevalent in rural Africa, but supplementation, often with cow's milk is frequently introduced before the age of 6 months. In Belize, the Maya Indians commonly feed their infants from birth until 12-18 months exclusively on breast milk. Asthma and hypersensitivity reactions to cow's milk and housedust mite in Maya children in Southern Belize and in a control group of Mestizo children from an urban area was studied. All the children aged 5-9 years attending the 2 schools in the study and control areas were studied. No child in the Maya village school admitted to or was known by the nurse or teachers to have asthma, whereas 2 of 39 children in the control group were known to be affected. The results of the prick tests show that the Maya children had significantly fewer positive reactions to both housedust mite and cow's milk. Reactivity to the 2 antigents was significantly correlated. Both tests were positive in 19 cases, both negative in 52, while only 7 were dust mite positive and cow's milk negative and only 2 were dust mite negative and milk positive. The housedust mite is widely prevalent, so the low incidence of positive reactions and the associated absence of asthma may be related to the traditional feeding pattern in Africa.^ieng

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