Environmental surveillance for Salmonella Typhi and its association with typhoid fever incidence in India and Malawi
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Published version
Author(s)
Type
Journal Article
Abstract
BACKGROUND: Environmental surveillance (ES) for Salmonella Typhi potentially offers a low-cost tool to identify communities with a high burden of typhoid fever. METHODS: We developed standardised protocols for typhoid ES, including sampling site selection, validation, characterisation; grab or trap sample collection, concentration; and quantitative PCR targeting Salmonella genes (ttr, staG and tviB) and a marker of human faecal contamination (HF183). ES was implemented over 12-months in a historically high typhoid fever incidence setting (Vellore, India) and a lower incidence setting (Blantyre, Malawi) during 2021-2022. RESULTS: S. Typhi prevalence in ES samples was higher in Vellore compared with Blantyre; 39/520 (7.5%, 95% Confidence Interval 4.4-12.4%) vs. 11/533 (2.1%, 1.1-4.0%) in grab and 79/517 (15.3%, 9.8-23.0%) vs. 23/594 (3.9%, 1.9-7.9%) in trap samples. Detection was clustered by ES site and correlated with site catchment population in Vellore but not Blantyre. Incidence of culture-confirmed typhoid in local hospitals was low during the study and zero some months in Vellore despite S. Typhi detection in ES. CONCLUSIONS: ES describes the prevalence and distribution of S. Typhi even in the absence of typhoid cases and could inform vaccine introduction. Expanded implementation and comparison with clinical and serological surveillance will further establish its public health utility.
Date Issued
2024-04-15
Date Acceptance
2023-09-28
Citation
Journal of Infectious Diseases, 2024, 229 (4), pp.979-987
ISSN
0022-1899
Publisher
Oxford University Press
Start Page
979
End Page
987
Journal / Book Title
Journal of Infectious Diseases
Volume
229
Issue
4
Copyright Statement
© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of
America. This is an Open Access article distributed under the terms of the Creative Commons Attribution
License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and
reproduction in any medium, provided the original work is properly cited.
America. This is an Open Access article distributed under the terms of the Creative Commons Attribution
License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and
reproduction in any medium, provided the original work is properly cited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/37775091
Subjects
India
Malawi
Salmonella Typhi
typhoid fever
typhoid-paratyphoid vaccines
wastewater surveillance
Publication Status
Published
Coverage Spatial
United States
Article Number
jiad427
Date Publish Online
2023-09-29