Ecoepidemiologia de Ascaris lumbricoides en una zona endemica y su relacion con los grupos sanguineos / Ecoepidemiology of Ascaris lumbricoides in an endemic area and its relation with the blood groups

185 children 1 to 14 years old living in the suburb of San Rafael (Zulia State, Venezuela) were selected for this study with the following results: Eggs of Ascaris lumbricoides in the stool samples before administration of a drug to the children and the worms recovered after drug, induced expulsion, showed a high aggregation (K = 0.115 and K = 0.122, respectively); the aggregation of the recovered worms was more intense in girls (K = 0.083), than in boys (K = 0.220); among the blood groups, A. lumbricoides resulted highly prevalent (100 percent) and less overdispersed in group AB (K = 1.26; n = 5), while in the other blood groups the spatial aggregation pattern was strongly overdispersed (A = 0.159; B = 0.133 and O = 0.210); individuals of the blood group rBr, make the greatest contribution to environmental contamination, because they presented the greatest values for the abundance and a more intense overdispersion

Nuevo enfoque para la interpretacion de la coproscopia cuantitativa en humanos / New interpretation of the quantitative fecal examination in humans

The pattern of spatial disposition of eggs of the parasites (Ascaris lumbricoides, Trichuris trichiura and Ancylostomidae) into the faeces was found overdispersed, independently of the technique of prodiagnosis used (Direct smear without standarisation, Stoll, Shore & Lynch, Kato-Katz and Mc Master). Therefore, differences were not detected in the interpretation of the results among the techniques at the population level, in quantitative studies. In an overdispersed pattern, only few hosts are the major responsibles for the environmental contamination. The importance of this spatial arrangement for parasite control purposes, is discussed