Part I. Analysis of data gaps pertaining to Salmonella enterica serotype Typhi infections in low and medium human development index countries, 1984-2005

There are only 10 contemporary, population-based studies of typhoid fever that evaluate disease incidence using blood Culture for confirmation of cases. Reported incidence ranged from 13 to 976/100000 persons per year. These studies are likely to have been done preferentially in high-incidence sites which makes generalization of data difficult. Only five of these Studies reported mortality. Of these the median (range) mortality was 0% (0-1 center dot 8%). Since study conditions usually involved enhanced clinical management of patients and the studies were not designed to evaluate mortality as an outcome, their usefulness for generalizing case-fatality rates is uncertain. No contemporary population-based studies reported rates of complications. Hospital-based typhoid fever Studies reported median (range) complication rates of 2 center dot 8% (0 center dot 6-4 center dot 9%) for intestinal perforation and case-fatality rates of 2 center dot 0% (0-14 center dot 8%). Rates of complications other than intestinal perforation were not reported in contemporary hospital-based studies. Hospital-based studies capture information on the most severe illnesses among persons who have access to health-care services limiting their generalizability. Only two Studies have informed the current understanding of typhoid fever age distribution Curves. Extrapolation from population-based Studies Suggests that most typhoid Fever occurs among young children in Asia. To reduce gaps in the Current understanding of typhoid fever incidence, complications, and case-fatality rate, large population-based studies using blood Culture confirmation of cases are needed in representative sites, especially in low and medium human development index countries outside Asia.