Evidence map›Paper›PMID 41701741›Full record

ArticlePLoS neglected tropical diseases2026

Statistical methods for predicting the presence of Salmonella Typhi in wastewater samples at Asante Akyem Agogo, Ghana.

Sampson Twumasi-Ankrah, Michael Owusu, Michael Owusu-Ansah, Seidu Amenyaglo, Caleb Osei-Wusu Sarfo, Eric Darko, Portia Okyere Boakye, Christopher B Uzzell, Isobel M Blake, Nicholas C Grassly and 2 more

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Article in PLoS neglected tropical diseases, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

12 authors.

Sampson Twumasi-AnkrahDepartment of Statistics and Actuarial Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.ORCID https://orcid.org/0000-0003-2196-0310
Michael OwusuDepartment of Medical Diagnostics, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Michael Owusu-AnsahDepartment of Community Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Seidu AmenyagloKNUST-IVI Collaborative Centre, Agogo, Ashanti Region, Ghana.
Caleb Osei-Wusu SarfoKNUST-IVI Collaborative Centre, Agogo, Ashanti Region, Ghana.
Eric DarkoDepartment of Clinical Microbiology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Portia Okyere BoakyeKNUST-IVI Collaborative Centre, Agogo, Ashanti Region, Ghana.
Christopher B UzzellDepartment of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.
Isobel M BlakeDepartment of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.
Nicholas C GrasslyDepartment of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.
Yaw Adu-SarkodieDepartment of Clinical Microbiology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
Ellis Owusu-DaboSchool of Public Health, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundMonitoring wastewater is vital for tracking typhoid fever in endemic areas. This study evaluated the performance of both spatial and non-spatial models in predicting Salmonella Typhi detection in wastewater from the Asante Akim North district in Ghana and identified key environmental risk factors.

methodsWe collected wastewater samples of Moore swabs at 40 sites across Agogo, Juansa, Hwidiem, and Domeabra over a period of 27 months. Multiplex PCR was used to detect Salmonella Typhi, focusing on the ttr, tviB, and staG genes. An Aquaprobe AP-2000 was also used to measure different physicochemical factors, such as pH, temperature, dissolved oxygen, and salinity. Three non-spatial models, namely Generalized Estimating Equations (Logistic), Mixed-Effects Models, and Random Forest, as well as four spatial models, including Bayesian Generalized Additive Models (GAM) and Spatial Generalized Linear Mixed Models (GLMM), were fitted to the wastewater dataset. Model fitting was done using 5-fold cross-validation, stratified by site. Model performance was evaluated using accuracy, sensitivity, and specificity. We also used SHapley Additive exPlanations (SHAP) analysis to find the most important predictors.

findingsIn general, 44.13% of the samples tested positive for S. Typhi. Detection was much higher during wet seasons (50.17% vs. 35.11%; p < 0.001), with fast flows (64.45%), and in channels that were 1-2 meters wide (58.70%). Positive samples had relatively higher pH (7.46 vs. 7.40; p < 0.001), dissolved oxygen (46.97% vs. 36.77%; p < 0.001), and rainfall (3.92mm vs. 3.30mm; p = 0.022). In comparing both non-spatial and spatial models, the non-spatial Random Forest model demonstrated the highest performance with an accuracy of 0.993, sensitivity of 0.997, and specificity of 0.989. In the SHAP analysis of the preferred non-spatial random forest model, it was found that pH, season, dissolved oxygen, positivity from the previous month, and channel width were identified as the best predictors.

conclusionS. Typhi detection is influenced by wastewater physicochemical properties, with pH, seasonal rainfall, and hydraulic conditions being the most significant. The non-spatial random forest model significantly outperforms both spatial and other non-spatial statistical methods.

Indexed as

Salmonella typhiWastewaterGhanaHumansModels, StatisticalMultiplex Polymerase Chain ReactionSensitivity and SpecificityTyphoid FeverWastewater

Identifiers

PMID41701741
PMCPMC12923122

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