{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T17:51:38Z","timestamp":1782323498300,"version":"3.54.5"},"reference-count":31,"publisher":"Public Library of Science (PLoS)","issue":"6","license":[{"start":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T00:00:00Z","timestamp":1782259200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"\n Background<\/jats:title>\n 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\u00a0under explored\u00a0in mathematical modeling studies.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n 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,\n R<\/jats:italic>\n 0<\/jats:sub>\n 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\n \n \n \n \n \n \n R<\/mml:mi>\n 0<\/mml:mn>\n <\/mml:msub>\n \u2264<\/mml:mo>\n 1<\/mml:mn>\n <\/mml:mrow>\n <\/mml:math>\n <\/jats:alternatives>\n <\/jats:inline-formula>\n and\n R<\/jats:italic>\n 0<\/jats:sub>\n \u2009>\u20091, 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\u2019s 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.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n Simulation results indicate that the combined implementation of environmental sanitation measures and educational interventions significantly reduces disease burden, particularly during outbreak periods.<\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n These findings highlight the importance of integrating environmental management and community-based public health strategies in typhoid control programs.<\/jats:p>\n <\/jats:sec>","DOI":"10.1371\/journal.pone.0351747","type":"journal-article","created":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T17:29:41Z","timestamp":1782322181000},"page":"e0351747","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Optimal control of Typhoid fever transmission under environmental and public health interventions"],"prefix":"10.1371","volume":"21","author":[{"given":"John","family":"Amoah-Mensah","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Mohamedahmed","family":"Mirghani Hassan Mohamed","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Reindorf","family":"Nartey Borkor","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rhoda","family":"Afutu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8086-8333","authenticated-orcid":true,"given":"Nicholas Kwasi-Do Ohene","family":"Opoku","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,6,24]]},"reference":[{"issue":"12","key":"pone.0351747.ref001","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pntd.0004212","article-title":"Environmental Transmission of Typhoid Fever in an Urban Slum","volume":"9","author":"A Akullian","year":"2015","journal-title":"PLoS Negl Trop Dis"},{"issue":"2","key":"pone.0351747.ref002","doi-asserted-by":"crossref","first-page":"300","DOI":"10.18203\/2349-3933.ijam20171035","article-title":"Typhoid fever: a review","volume":"4","author":"UK Paul","year":"2017","journal-title":"Int J Adv Med"},{"key":"pone.0351747.ref003","doi-asserted-by":"crossref","DOI":"10.1093\/cid\/ciz611","article-title":"The Invisible Burden: Diagnosing and Combatting Typhoid Fever in Asia and Africa","volume":"69","author":"VE Pitzer","year":"2019","journal-title":"Clin Infect Dis"},{"key":"pone.0351747.ref004","doi-asserted-by":"crossref","DOI":"10.1093\/cid\/ciaa1321","article-title":"Healthcare Utilization Patterns for Acute Febrile Illness in Bangladesh, Nepal, and Pakistan: Results from the Surveillance for Enteric Fever in Asia Project","volume":"71","author":"JR Andrews","year":"2020","journal-title":"Clin Infect Dis"},{"key":"pone.0351747.ref005","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1016\/j.procs.2022.12.138","article-title":"Data mining for epidemiology: The correlation of typhoid fever occurrence and environmental factors","volume":"216","author":"F Asadi","year":"2023","journal-title":"Procedia Computer Science"},{"key":"pone.0351747.ref006","doi-asserted-by":"crossref","unstructured":"Nthiiri J. Mathematical modelling of typhoid fever disease incorporating protection against infection. 2016.","DOI":"10.9734\/BJMCS\/2016\/23325"},{"key":"pone.0351747.ref007","doi-asserted-by":"crossref","first-page":"41","DOI":"10.1016\/j.ijid.2022.03.036","article-title":"Toward Typhoid Fever Elimination","volume":"119","author":"F Khanam","year":"2022","journal-title":"Int J Infect Dis"},{"issue":"05","key":"pone.0351747.ref008","first-page":"1","article-title":"A deterministic mathematical model for direct and indirect transmission dynamics of typhoid fever","volume":"4","author":"S Edward","year":"2017","journal-title":"Open Access Library Journal"},{"issue":"2","key":"pone.0351747.ref009","first-page":"64","article-title":"Solution of a deterministic mathematical model of typhoid fever by variational iteration method","volume":"13","author":"O Peter","year":"2018","journal-title":"Science World Journal"},{"key":"pone.0351747.ref010","doi-asserted-by":"crossref","first-page":"100153","DOI":"10.1016\/j.rinam.2021.100153","article-title":"Dynamics analysis of typhoid fever with public health education programs and final epidemic size relation","volume":"10","author":"SS Musa","year":"2021","journal-title":"Results in Applied Mathematics"},{"key":"pone.0351747.ref011","doi-asserted-by":"crossref","first-page":"65","DOI":"10.12988\/asb.2015.41059","article-title":"Mathematical analysis of typhoid model with saturated incidence rate","volume":"7","author":"MA Khan","year":"2015","journal-title":"asb"},{"key":"pone.0351747.ref012","article-title":"Mathematical Modeling to Assess the Drivers of the Recent Emergence of Typhoid Fever in Blantyre, Malawi","author":"VE Pitzer","year":"2015","journal-title":"Clin Infect Dis"},{"issue":"1","key":"pone.0351747.ref013","first-page":"44","article-title":"Modelling typhoid fever with education, vaccination and treatment","volume":"1","author":"S Edward","year":"2016","journal-title":"Eng Math"},{"issue":"4","key":"pone.0351747.ref014","first-page":"298","article-title":"Modeling the impact of screening and treatment on the dynamics of typhoid fever","volume":"14","author":"N Nyerere","year":"2018","journal-title":"World Journal of Modelling and Simulation"},{"key":"pone.0351747.ref015","doi-asserted-by":"crossref","first-page":"104463","DOI":"10.1016\/j.rinp.2021.104463","article-title":"Direct and indirect transmission of typhoid fever model with optimal control","volume":"27","author":"OJ Peter","year":"2021","journal-title":"Results in Physics"},{"issue":"4","key":"pone.0351747.ref016","doi-asserted-by":"crossref","first-page":"965","DOI":"10.1016\/j.vaccine.2022.12.032","article-title":"Comparison of model predictions of typhoid conjugate vaccine public health impact and cost-effectiveness","volume":"41","author":"H Burrows","year":"2023","journal-title":"Vaccine"},{"issue":"02","key":"pone.0351747.ref017","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1142\/S0218339022500164","article-title":"Modeling the role of vaccination, environmental sanitation, and saturated treatment on the spread of typhoid fever","volume":"30","author":"TK Irena","year":"2022","journal-title":"J Biol Syst"},{"key":"pone.0351747.ref018","doi-asserted-by":"crossref","DOI":"10.3389\/fams.2023.1151270","article-title":"A mathematical model on the transmission dynamics of typhoid fever with treatment and booster vaccination","volume":"9","author":"A Kailan Suhuyini","year":"2023","journal-title":"Front Appl Math Stat"},{"key":"pone.0351747.ref019","doi-asserted-by":"crossref","first-page":"2324518","DOI":"10.1155\/2017\/2324518","article-title":"Modelling and Optimal Control of Typhoid Fever Disease with Cost-Effective Strategies","volume":"2017","author":"GT Tilahun","year":"2017","journal-title":"Comput Math Methods Med"},{"key":"pone.0351747.ref020","doi-asserted-by":"crossref","first-page":"111074","DOI":"10.1016\/j.chaos.2021.111074","article-title":"Mathematical modeling, forecasting, and optimal control of typhoid fever transmission dynamics","volume":"149","author":"H Abboubakar","year":"2021","journal-title":"Chaos, Solitons & Fractals"},{"issue":"1","key":"pone.0351747.ref021","doi-asserted-by":"crossref","first-page":"15284","DOI":"10.1038\/s41598-023-42244-5","article-title":"The stability analysis of a nonlinear mathematical model for typhoid fever disease","volume":"13","author":"IU Khan","year":"2023","journal-title":"Sci Rep"},{"issue":"1","key":"pone.0351747.ref022","doi-asserted-by":"crossref","first-page":"21993","DOI":"10.1038\/s41598-023-48405-w","article-title":"Numerical investigation of a typhoid disease model in fuzzy environment","volume":"13","author":"F Dayan","year":"2023","journal-title":"Sci Rep"},{"issue":"5","key":"pone.0351747.ref023","doi-asserted-by":"crossref","first-page":"6213","DOI":"10.1007\/s40808-024-02111-2","article-title":"A non-linear mathematical model for typhoid fever transmission dynamics with medically hygienic compartment","volume":"10","author":"FO Lawal","year":"2024","journal-title":"Model Earth Syst Environ"},{"issue":"1","key":"pone.0351747.ref024","article-title":"Transmission dynamics of typhoid fever with nonlinear incidence rate and saturated treatment","volume":"14","author":"Laxman","year":"2025","journal-title":"Int J Dynam Control"},{"issue":"1","key":"pone.0351747.ref025","doi-asserted-by":"crossref","first-page":"1212057","DOI":"10.1155\/jom\/1212057","article-title":"Mathematical Modeling and Cost-Effectiveness Analysis of an SeEeIeRe Typhoid Fever Model","volume":"2025","author":"S Nana-Kyere","year":"2025","journal-title":"Journal of Mathematics"},{"key":"pone.0351747.ref026","doi-asserted-by":"crossref","DOI":"10.2196\/67544","article-title":"Risk Factors for Typhoid Fever: Systematic Review","volume":"11","author":"P Boakye Okyere","year":"2025","journal-title":"JMIR Public Health Surveill"},{"issue":"7","key":"pone.0351747.ref027","doi-asserted-by":"crossref","first-page":"2928","DOI":"10.4249\/scholarpedia.2928","article-title":"Nelder-Mead algorithm","volume":"4","author":"S Singer","year":"2009","journal-title":"Scholarpedia"},{"issue":"3","key":"pone.0351747.ref028","doi-asserted-by":"crossref","first-page":"482","DOI":"10.4269\/ajtmh.22-0427","article-title":"Evaluation of Sampling and Concentration Methods for Salmonella enterica Serovar Typhi Detection from Wastewater","volume":"108","author":"N Zhou","year":"2023","journal-title":"Am J Trop Med Hyg"},{"key":"pone.0351747.ref029","doi-asserted-by":"crossref","first-page":"107120","DOI":"10.1016\/j.rinp.2023.107120","article-title":"Modeling the impact of screening and treatment on typhoid fever dynamics in unprotected population","volume":"54","author":"JI Irunde","year":"2023","journal-title":"Results in Physics"},{"key":"pone.0351747.ref030","unstructured":"Lewis AD. The maximum principle of Pontryagin in control and in optimal control. 2006."},{"key":"pone.0351747.ref031","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1155\/2022\/9084283","article-title":"Modelling the Transmission Dynamics of Meningitis among High and Low-Risk People in Ghana with Cost-Effectiveness Analysis","volume":"2022","author":"NK-DO Opoku","year":"2022","journal-title":"Abstract and Applied Analysis"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0351747","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,24]],"date-time":"2026-06-24T17:29:54Z","timestamp":1782322194000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0351747"}},"subtitle":[],"editor":[{"given":"Oluwole Daniel","family":"Makinde","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,6,24]]},"references-count":31,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2026,6,24]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0351747","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,6,24]]}}}