ANALYSIS OF INCIDENCE OF INFECTION WITH ENTEROTOXIGENIC ESCHERICHIA-COLI IN A PROSPECTIVE COHORT STUDY OF INFANT DIARRHEA IN NICARAGUA

Diarrheal episodes with enterotoxigenic Escherichia coli (ETEC) were p rospectively monitored during the first 2 years of life in a cohort of 235 infants from Leon, Nicaragua. ETEC was an etiological finding in 38% (310 of 808) of diarrheal episodes and in 19% (277 of 1,472) of sa mples taken as asymptomatic controls at defined age intervals (P = <0. 0001). The majority of diarrheal episodes (80%) occurred before 12 mon ths of age, The major ETEC type was characterized by colonization fact or CFA I and elaboration of both heat-labile enterotoxin and heat-stab le enterotoxin (ST), The proportion of E. coli strains,vith CFA I was significantly higher in cases with diarrhea (P = 0.002). The second mo st prevalent type showed putative colonization factor PCFO166 and prod uction of ST. The prevalence of PCFO166 was approximately 20%, higher than reported before. Children with a first CFA I episode contracted a second ETEC CFA I infection 24% of the time, compared with 46% for ET EC strains of any subtype, Most of the ETEC episodes were of moderate severity, and only 5% (15 of 310) were characterized as severe. In con clusion, our results give valuable information for the planning of int ervention studies using ETEC vaccines.