ABSTRACT
The hypothesis that blood phenotype B is associated to typhoid fever either directly or interacting with other phenotypes of the Rh or MNSs blood systems was tested. 256 children from the Northern Area of Santiago (Chile) with bacteriologically confirmed typhoid fever and 329 afebrile controls matched by age and gender from the same population, were studied. Association was found between phenotype RH3 and protection against disease for the whole group (OR = 0.67; p < 0.042) and for males (OR = 0.05; p = 0.014) although the gender-RH3 interaction was at the limit of significance. RH8 and Ss phenotypes were associated to increased susceptibility (OR = 1.83; p < 0.034 and OR = 1.56; p = 0.01, respectively). Controlling RH3 and Ss phenotypes by B, increased their effects (OR = 0.26; p = 0.04 and OR = 3.42; p = 0.026, respectively), but interactions did not reach statistical significance. These results show a susceptibility cline whose implications and applicability deserve further studies. A high proportion of S. paratyphi B (23.8%) appeared in this series, which may imply sample heterogeneity. The meaning of these findings need further epidemiological and genetic studies.
Subject(s)
Blood Group Antigens , Typhoid Fever/blood , Child , Female , Humans , Male , PhenotypeABSTRACT
We surveyed a probabilistic sample of 1383 school children attending elementary school (5th to 8th grade) in La Pincoya, a neighborhood of northern Santiago. 53.7% had smoked at least once, and 1 out of 5 were regular smokers of 1-4 cigarettes (72%) or more than 5 cigarettes a day (14%). The incidence of smoking was higher among boys and increased with age. Smoking occurs in different places including the street (19%). About 60% of children get their cigarettes from other children or adults. Those who buy, do so by units rather than packs. The incidence of smoking raised to 64% among children of parents who smoked. Pleasure or imitation were quoted as main reasons for smoking.
