RISK-FACTORS FOR TYPHOID-FEVER IN AN ENDEMIC SETTING, KARACHI, PAKISTAN

We conducted a study to evaluate risk factors for developing typhoid f ever in a setting where the disease is endemic in Karachi, Pakistan. W e enrolled 100 cases with blood culture-confirmed Salmonella typhi bet ween July and October 1994 and 200 age-matched neighbourhood controls. Cases had a median age of 5.8 years. In a conditional logistic regres sion model, eating ice cream (Odds ratio [OR] = 2.3; 95% confidence in terval [CI] 1.2-4.2, attributable risk [AR] = 36%), eating food from a roadside cabin during the summer months (OR = 4.6, 95% CI 1.6-13.0; A R = 18%), taking antimicrobials in the 2 weeks preceding the onset of symptoms (OR = 5.7, 95% CI 2.3-13.9, AR = 21%), and drinking water at the work-site (OR = 44.0, 95% CI 2.8-680, AR = 8%) were all independen tly associated with typhoid fever. There was no difference in the micr obiological water quality of home drinking water between cases and con trols. Typhoid fever in Karachi resulted from high-dose exposures from multiple sources with individual susceptibility increased by young ag e and prior antimicrobial use. Improving commercial food hygiene and d ecreasing unnecessary antimicrobial use would be expected to decrease the burden of typhoid fever.