Jacob John, M.D., Ph.D., Ashish Bavdekar, D.N.B., Temsunaro Rongsen-Chandola, Ph.D., Shanta Dutta, M.D., Ph.D., Madhu Gupta, M.D., Ph.D., Suman Kanungo, Ph.D., Bireshwar Sinha, M.D., Manikandan Srinivasan, M.D., Ankita Shrivastava, M.P.H., Adarsh Bansal, M.P.H., Ashita Singh, M.D., Roshine M. Koshy, M.D., Dasharatha R. Jinka, M.D., Mathew S. Thomas, M.D., Anna P. Alexander, M.D., Shajin Thankaraj, M.D., Sheena E. Ebenezer, M.D., Arun S. Karthikeyan, Ph.D., Dilesh Kumar, M.P.H., K. N Swathi, M.D., Reshma Raju, M.D., M.P.H., Nikhil Sahai, B.Tech., Balaji Veeraraghavan, M.D., Ph.D., Manoj V. Murhekar, M.D., Venkata R. Mohan, M.D., Sindhu K. Natarajan, M.D., Ph.D., Karthikeyan Ramanujam, Ph.D., Prasanna Samuel, Ph.D., Nathan C. Lo, M.D., Ph.D., Jason Andrews, M.D., Nicholas C. Grassly, D.Phil., Gagandeep Kang, M.D., Ph.D., and NSSEFI team
Background: In 2017, more than half the cases of typhoid fever worldwide were projected to have occurred in India. In the absence of contemporary population-based data, it is unclear whether declining trends of hospitalization for typhoid in India reflect increased antibiotic treatment or a true reduction in infection.
Methods: From 2017 through 2020, we conducted weekly surveillance for acute febrile illness and measured the incidence of typhoid fever (as confirmed on blood culture) in a prospective cohort of children between the ages of 6 months and 14 years at three urban sites and one rural site in India. At an additional urban site and five rural sites, we combined blood-culture testing of hospitalized patients who had a fever with survey data regarding health care use to estimate incidence in the community.
Results: A total of 24,062 children who were enrolled in four cohorts contributed 46,959 child-years of observation. Among these children, 299 culture-confirmed typhoid cases were recorded, with an incidence per 100,000 child-years of 576 to 1173 cases in urban sites and 35 in rural Pune. The estimated incidence of typhoid fever from hospital surveillance ranged from 12 to 1622 cases per 100,000 child-years among children between the ages of 6 months and 14 years and from 108 to 970 cases per 100,000 person-years among those who were 15 years of age or older. Salmonella enterica serovar Paratyphi was isolated from 33 children, for an overall incidence of 68 cases per 100,000 child-years after adjustment for age.
Conclusions: The incidence of typhoid fever in urban India remains high, with generally lower estimates of incidence in most rural areas.
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