Differential age effects in seasonal variation of mortality in a rural Zapotec-speaking municipio, 1945-1970

Seasonal variation in deaths registered from 1945 to 1970 in a rural Zapotec speaking community in Oaxaca, Mexico was analyzed. Total mortality for the community showed the highest incidence during the 5 mth rainy season. When data were analyzed by age into infant, early childhood and other ages, it was apparent that the major component of the seasonal influence was due to higher than expected mortality in children 1 through 4 yr of age. Infant mortality and its components, neonatal and nonneonatal mortality, did not show seasonal variation in this rural community. Thus, the rainy months are particularly hazardous for children 1 through 4 yr of age. Examination of reported causes of death implicates conditions associated with gastrointestinal disorders during the rainy season, as 2/3 of the deaths attributed to gastrointestinal disorders in the 1 through 4 yr old age group occur during the 5 rainy mth. Although infant mortality in this community is high, the lack of seasonal variation in infant mortality may be related to breast feeding.