Epidemiologic investigations of dengue infection in Mexico, 1980

A binational investigation was conducted in two Mexican cities in 1980 to study epidemiologic characteristics of dengue. Two study areas were selected in each of the cities (Merida and Tampico); in each area, in February and in September, sanitarians recorded information concerning abundance of Aedes aegypti, and public health nurses obtained blood specimens and clinical information from residents. Ninety-nine individuals (24% of the study population) showed serologic evidence of recent dengue 1 infection by hemagglutination inhibition or complement fixation. Infection rates in the four study areas (9%-51%) increased with age in three of the four areas and were higher in females in all four areas. These differences in rates may be related to exposure to infectious mosquitoes in the home; A. aegypti feed most actively during daylight hours, and both females (p less than 0.001) and older individuals (p less than 0.001) were more likely than males or younger persons to be in the home when the study was conducted. A positive correlation was found between infection rates and the container index (number of potential A. aegypti breeding sites per premise--Pearson correlation coefficient 0.95, p = 0.05), suggesting that this index may be a useful predictor of neighborhoods at high risk of dengue transmission. Pending additional studies, public cleanup campaigns should be targeted to neighborhoods in which container indices are highest when an outbreak of dengue is likely to occur.