Incidence of typhoid bacteremia in infants and young children in southern coastal Pakistan

Abstract

Introduction: The burden of typhoid fever in preschool children is not well recognized. The purpose of this study was to estimate the incidence of typhoid bacteremia in Pakistani children <5 years of age, with a focus on children younger than 2 years of age. This will help to inform prevention policies in highly endemic countries.

Methods: Household surveillance from February 1, 2007 to May 12, 2008, was carried out by community health workers in 2 low-income, coastal communities of Karachi. Workers referred each sick child <5 years old to the local clinic. Blood for culture was obtained from those who gave consent, and inoculated in BACTEC Peds Plus bottles (Becton Dickinson, Sparks, MD) and processed per manufacturer's guidelines.

Results: Overall, 5570 children contributed 3949 observation years. Blood culture was obtained from 1165 cases, yielding 36 pathogens. Salmonella Typhi was isolated in 16 cases, Salmonella Paratyphi A in 2 cases, and Salmonella Paratyphi B in 1 case. The incidence of typhoid bacteremia in children <2 years of age was 443.1 (95% confidence interval, 193.8-876.5) per 100,000 child years. The overall incidence rate of typhoid for children <5 years was 405.1 (95% confidence interval, 239.8-643.9) per 100,000 child years.

Conclusion: Typhoid is a common and significant cause of morbidity among young children in Pakistan, including children less than 2 years of age. Vaccines that provide protection to preschool children should be included in typhoid control efforts.