Estimating the Seroincidence of Scrub Typhus using Antibody Dynamics after Infection
1
Issued Date
2024-08-07
Resource Type
eISSN
14761645
Scopus ID
2-s2.0-85201029677
Pubmed ID
38861980
Journal Title
The American journal of tropical medicine and hygiene
Volume
111
Issue
2
Start Page
267
End Page
276
Rights Holder(s)
SCOPUS
Bibliographic Citation
The American journal of tropical medicine and hygiene Vol.111 No.2 (2024) , 267-276
Suggested Citation
Aiemjoy K., Katuwal N., Vaidya K., Shrestha S., Thapa M., Teunis P., Bogoch I.I., Trowbridge P., Blacksell S.D., Paris D.H., Wangrangsimakul T., Varghese G.M., Maude R.J., Tamrakar D., Andrews J.R. Estimating the Seroincidence of Scrub Typhus using Antibody Dynamics after Infection. The American journal of tropical medicine and hygiene Vol.111 No.2 (2024) , 267-276. 276. doi:10.4269/ajtmh.23-0475 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/100538
Title
Estimating the Seroincidence of Scrub Typhus using Antibody Dynamics after Infection
Author's Affiliation
Faculty of Tropical Medicine, Mahidol University
Mahidol Oxford Tropical Medicine Research Unit
The University of Hong Kong Li Ka Shing Faculty of Medicine
MSU College of Human Medicine
Dhulikel Hospital, Kathmandu
Stanford University School of Medicine
Rollins School of Public Health
Universität Basel
UC Davis School of Medicine
Swiss Tropical and Public Health Institute Swiss TPH
University of Toronto Faculty of Medicine
The Open University
Nuffield Department of Medicine
Christian Medical College, Vellore
Mahidol Oxford Tropical Medicine Research Unit
The University of Hong Kong Li Ka Shing Faculty of Medicine
MSU College of Human Medicine
Dhulikel Hospital, Kathmandu
Stanford University School of Medicine
Rollins School of Public Health
Universität Basel
UC Davis School of Medicine
Swiss Tropical and Public Health Institute Swiss TPH
University of Toronto Faculty of Medicine
The Open University
Nuffield Department of Medicine
Christian Medical College, Vellore
Corresponding Author(s)
Other Contributor(s)
Abstract
Scrub typhus, a vector-borne bacterial infection, is an important but neglected disease globally. Accurately characterizing the burden is challenging because of nonspecific symptoms and limited diagnostics. Prior seroepidemiology studies have struggled to find consensus cutoffs that permit comparisons of estimates across contexts and time. In this study, we present a novel approach that does not require a cutoff and instead uses information about antibody kinetics after infection to estimate seroincidence. We use data from three cohorts of scrub typhus patients in Chiang Rai, Thailand, and Vellore, India, to characterize antibody kinetics after infection and two population serosurveys in the Kathmandu Valley, Nepal, and Tamil Nadu, India, to estimate seroincidence. The samples were tested for IgM and IgG responses to Orientia tsutsugamushi-derived recombinant 56-kDa antigen using commercial enzyme-linked immunosorbent assay kits. We used Bayesian hierarchical models to characterize antibody responses after scrub typhus infection and used the joint distributions of the peak antibody titers and decay rates to estimate population-level incidence rates in the cross-sectional serosurveys. Median responses persisted above an optical density (OD) of 1.8 for 23.6 months for IgG and an OD of 1 for 4.5 months for IgM. Among 18- to 29-year-olds, the seroincidence was 10 per 1,000 person-years (95% CI, 5-19) in Tamil Nadu, India, and 14 per 1,000 person-years (95% CI: 10-20) in the Kathmandu Valley, Nepal. When seroincidence was calculated with antibody decay ignored, the disease burden was underestimated by more than 50%. The approach can be deployed prospectively, coupled with existing serosurveys, or leverage banked samples to efficiently generate scrub typhus seroincidence estimates.