| Summary: | To clarify the existance of reinfection in children bearing an established Ascaris lumbricoides infection, the authors evaluated the weight and the length of worms collected from ten cases of ascaridiasis. The worm burden was greater than 27 worms in nine cases. In seven cases the weight and the length of worms showed little variation, with unimodal distribution of values, suggesting that all the worms in each case belong to the same population, originated from a single brood infection or from successive infections over small time intervals. In three cases there was great variation in worm size indicated by the different values for the means and medians and by the high values for the standard deviation and coefficient of variation. In these three cases there was a bimodal distribution of worm's size suggesting the coexistance of two distinct populations: one, less numerous, composed of mature worms and the other, more numerous, composed ofimmature worms, in two cases, and two distinct populations of immature worms in one case. The existance of worms in different stages of maturation indicates that the less mature population was acquired when the mature worms were established in the gut. These results indicate that the reinfection with Ascaris in children bearing an established infection is not rare and resistance induced by a preexisting infection is not the rule. Para tentar esclarecer a existência de reinfecção em crianças portadoras de ascaridíase já estabelecida, foram avaliados o peso e o comprimento dos vermes colhidos em 10 casosde ascaridíase, em nove dos quais a carga parasitária foi maior do que 27 vermes. Em sete casos o peso e o comprimento dos vermes apresentaram pouca variação, com distribuição unimodal dos valores, sugerindo assim pertencerem todos a uma mesma população originada de uma única infecção ou de infecções repetidas com intervalos muito curtos. Em três casos, o peso e o comprimento dos vermes mostraram grande variação, indicada pelos valores diferentes para as médias e as medianas e dos ...
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