Environmental surveillance for Salmonella Typhi and its association with typhoid fever incidence in India and Malawi.
India
Malawi
Salmonella Typhi
typhoid fever
typhoid-paratyphoid vaccines
wastewater surveillance
Journal
The Journal of infectious diseases
ISSN: 1537-6613
Titre abrégé: J Infect Dis
Pays: United States
ID NLM: 0413675
Informations de publication
Date de publication:
29 Sep 2023
29 Sep 2023
Historique:
received:
07
07
2023
revised:
15
09
2023
accepted:
26
09
2023
medline:
30
9
2023
pubmed:
30
9
2023
entrez:
29
9
2023
Statut:
aheadofprint
Résumé
Environmental surveillance (ES) for Salmonella Typhi potentially offers a low-cost tool to identify communities with a high burden of typhoid fever. 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. 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. 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.
Sections du résumé
BACKGROUND
BACKGROUND
Environmental surveillance (ES) for Salmonella Typhi potentially offers a low-cost tool to identify communities with a high burden of typhoid fever.
METHODS
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
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
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.
Identifiants
pubmed: 37775091
pii: 7286615
doi: 10.1093/infdis/jiad427
pii:
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Informations de copyright
© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.