biostudies-literatureDevamani CSMedical Research Councile132https://www.ebi.ac.uk/biostudies/studies/S-EPMC9306010biostudies-literatureUnknown150Scrub typhus is a common bacterial infection in Asia caused by <i>Orientia tsutsugamushi</i>. This serological cohort study estimated the incidence of infection in a rural population in South India. Participants were enrolled through systematic sampling in 46 villages at baseline, and revisited the following year. Blood samples were tested for IgG antibodies using ELISA, followed by indirect immunofluorescence assays (IFA) in those positive for ELISA at both rounds. A case was defined as sero-conversion (ELISA), or at least a 4-fold titre increase (IFA), between the two time points. In addition to crude incidence rate estimates, we used piecewise linear rates across calendar months, with rates proportional to the monthly incidence of local hospital cases to address seasonality and unequal Epidemiology and infectionThe incidence of <i>Orientia tsutsugamushi</i> infection in rural South India.PMC9306010MR/S023275/1Devamani CSPrakash JAJAlexander NStenos JSchmidt WPfalseThe incidence of <i>Orientia tsutsugamushi</i> infection in rural South India.Scrub typhus is a common bacterial infection in Asia caused by <i>Orientia tsutsugamushi</i>. This serological cohort study estimated the incidence of infection in a rural population in South India. Participants were enrolled through systematic sampling in 46 villages at baseline, and revisited the following year. Blood samples were tested for IgG antibodies using ELISA, followed by indirect immunofluorescence assays (IFA) in those positive for ELISA at both rounds. A case was defined as sero-conversion (ELISA), or at least a 4-fold titre increase (IFA), between the two time points. In addition to crude incidence rate estimates, we used piecewise linear rates across calendar months, with rates proportional to the monthly incidence of local hospital cases to address seasonality and unequal 2022-01-01T00:00:00Z2022 Jun2025-04-18T15:34:03.478Z2025-02-19T02:26:19.243ZS-EPMC93060103576516810.1017/S0950268822001170