Environmental surveillance for Salmonella Typhi as a tool to estimate the incidence of typhoid fever in low-income populations.

Uzzell, Christopher B., Troman, Catherine M., Rigby, Jonathan, Raghava Mohan, Venkata, John, Jacob, Abraham, Dilip, Srinivasan, Rajan, Nair, Satheesh, Meschke, John Scott, Elviss, Nicola, Kang, Gagandeep, Feasey, Nicholas ORCID: https://orcid.org/0000-0003-4041-1405 and Grassly, Nicholas C. (2023) 'Environmental surveillance for Salmonella Typhi as a tool to estimate the incidence of typhoid fever in low-income populations.'. Wellcome Open Research, Vol 8, e9.

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Abstract

Background: The World Health Organisation recommends prioritised use of recently prequalified typhoid conjugate vaccines in countries with the highest incidence of typhoid fever. However, representative typhoid surveillance data are lacking in many low-income countries because of the costs and challenges of diagnostic clinical microbiology. Environmental surveillance (ES) of Salmonella Typhi in sewage and wastewater using molecular methods may offer a low-cost alternative, but its performance in comparison with clinical surveillance has not been assessed.
Methods: We developed a harmonised protocol for typhoid ES and its implementation in communities in India and Malawi where it will be compared with findings from hospital-based surveillance for typhoid fever. The protocol includes methods for ES site selection based on geospatial analysis, grab and trap sample collection at sewage and wastewater sites, and laboratory methods for sample processing, concentration and quantitative polymerase chain reaction (PCR) to detect Salmonella Typhi. The optimal locations for ES sites based on digital elevation models and mapping of sewage and river networks are described for each community and their suitability confirmed through field investigation. We will compare the prevalence and abundance of Salmonella Typhi in ES samples collected each month over a 12-month period to the incidence of blood culture confirmed typhoid cases recorded at referral hospitals serving the study areas.
Conclusions: If environmental detection of Salmonella Typhi correlates with the incidence of typhoid fever estimated through clinical surveillance, typhoid ES may be a powerful and low-cost tool to estimate the local burden of typhoid fever and support the introduction of typhoid conjugate vaccines. Typhoid ES could also allow the impact of vaccination to be assessed and rapidly identify circulation of drug resistant strains.

Item Type:	Article
Subjects:	WA Public Health > WA 30 Socioeconomic factors in public health (General) WA Public Health > Sanitation. Environmental Control > General Sanitation and Environmental Control > WA 670 General works WA Public Health > Statistics. Surveys > WA 950 Theory or methods of medical statistics. Epidemiologic methods WC Communicable Diseases > Infection. Bacterial Infections > Enteric Infections > WC 269 Salmonella infections WC Communicable Diseases > Infection. Bacterial Infections > Enteric Infections > WC 270 Typhoid fever
Faculty: Department:	Clinical Sciences & International Health > Clinical Sciences Department
Digital Object Identifer (DOI):	https://doi.org/10.12688/wellcomeopenres.17687.1
SWORD Depositor:	JISC Pubrouter
Depositing User:	JISC Pubrouter
Date Deposited:	14 Mar 2023 13:06
Last Modified:	14 Mar 2023 13:06
URI:	https://archive.lstmed.ac.uk/id/eprint/21795

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