Published in PLOS One on 2026-06-24, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: John Amoah-Mensah, Mohamedahmed Mirghani Hassan Mohamed, Reindorf Nartey Borkor, Rhoda Afutu, Nicholas Kwasi-Do Ohene Opoku
Source: PLOS One • DOI 10.1371/journal.pone.0351747
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
This study investigates the transmission dynamics of typhoid fever and assesses the impact of environmental factors and public health interventions on disease spread. Typhoid fever, caused by Salmonella Typhi, remains a major public health concern in regions with poor sanitation, high population density, and limited access to clean water. Although environmental contamination plays a critical role in sustaining transmission, its contribution is often under explored in mathematical modeling studies.
We developed a deterministic compartmental model incorporating environmental transmission pathways to better understand the role of contaminated water sources and human-environment interactions in the spread of typhoid fever. The model is formulated as a system of nonlinear ordinary differential equations. The basic reproduction number, R0 was derived using the next-generation matrix approach to determine the threshold conditions for disease persistence. We analyzed the existence and stability of the disease-free and endemic equilibrium points, establishing local and global stability results for R0≤1 and R0 > 1, respectively. Sensitivity analysis on the reproduction number and the endemic equilibrium was conducted to identify parameters with the greatest influence on disease transmission. Furthermore, the model was extended to an optimal control framework incorporating two intervention strategies: public health education campaigns and treatment of contaminated water bodies. Pontryagin’s Maximum Principle was applied to characterize the optimal controls and derive the associated optimality system. Model parameters were estimated using reported typhoid fever data from Ethiopia obtained through the World Health Organization. Numerical simulations were performed to evaluate the impact of individual and combined intervention strategies.
Simulation results indicate that the combined implementation of environmental sanitation measures and educational interventions significantly reduces disease burden, particularly during outbreak periods.
These findings highlight the importance of integrating environmental management and community-based public health strategies in typhoid control programs.
Introduction
Typhoid fever is an infectious febrile disease caused by the bacterium Salmonella typhi [1]. The disease is strongly associated with inadequate sanitation, overcrowding, and informal settlements, where environmental conditions facilitate bacterial persistence and transmission [1]. It occurs in both rural and urban settings lacking reliable access to safe water and proper waste disposal systems. Transmission primarily occurs through ingestion of food or water contaminated with fecal material from infected individuals [2]. The clinical presentation typically includes prolonged fever, abdominal pain, malaise, headache, nausea, constipation and diarrhea, and general weakness [3]. In some cases, patients may develop a rash, and severe untreated infections can lead to life-threatening complications [4]. Symptoms may persist for several weeks. Importantly, asymptomatic individuals can shed the bacteria and contribute to continued transmission within the population [5]. Without appropriate treatment, mortality rates have been reported to reach approximately 10% [3].
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider public health desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 John Amoah-Mensah, Mohamedahmed Mirghani Hassan Mohamed, Reindorf Nartey Borkor, Rhoda Afutu, Nicholas Kwasi-Do Ohene Opoku. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
Explore connected evidence
- Evidence brief: Individual, community, and societal drivers of adolescent peer violence in Asella, Ethiopia: A school-based cross-sectional study utilizing the socio-ecological model
- Evidence brief: Implementation, enforcement, and monitoring of tobacco advertising, promotion, and sponsorship (TAPS) laws in Ethiopia: Insights from a qualitative study
- Evidence brief: Finite-time stability of the West Nile Virus model with Brownian motion
