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University of Zululand (2018)

Theoretical modelling of temperature and rainfall influence on Schistosoma species population dynamics

Adekiya, Tayo Alex

Titre : Theoretical modelling of temperature and rainfall influence on Schistosoma species population dynamics

Auteur : Adekiya, Tayo Alex

Université de soutenance : University of Zululand

Grade : Masters (MSc) in Biochemistry 2018

Résumé
Schistosomiasis, otherwise known as snail fever or bilharzia, is caused by parasitic at- worms called schistosomes. In human, these schistosomes infected the intestines or the urinary tract where they develop to form other acute and chronic diseases which include fever, malaise, severe abdominal pain, skin rashes, liver disease, lung disease, intestinal disease and urinary tract disease depending on the schistosomes. The reoccurrence of Schistosoma infections over the years may result into cancer of the bladder, obstruction in urinary tract, portal or pulmonary hypertension and even death. This study was de- veloped to investigate the in uence of temperature and rainfall on population dynamics of Schistosoma species over South Africa. Also, to investigate time-dependent control strategies, so as to ascertain the best cost-e ectiveness optimal control strategy for schis- tosomiasis eradication/control. In this study, a deterministic schistosomiasis climate-based model was developed using di erential equations. The numerical simulations of the system were done using MAT- LAB and Ferret software in order to examine the e ect of climate variability on the transmission dynamics of schistosomiasis. Furthermore, a deterministic model for the transmission of schistosomiasis disease and optimal control analysis of the model was also derived and analyzed. The model is found to exhibit multiple equilibria, the necessary conditions for the optimal control of the disease was derived and analyzed. In addition, the cost-e ectiveness of the controls was investigated in order to determine the most e ec- tive strategy to control the disease with minimum costs. Finally, the numerical solutions were presented. vi Numerical simulations showed that the impact of climate change on population dynamics of schistosomiasis infection is greatly pronounced on the production, survivability and fecundity rate of both freshwater snails and schistosomes. It was also showed by the nu- merical simulations that all the strategies employed for schistosomiasis control have great e ects both on the population of infected human and infected snail with control strate- gies B, D, F, G, I and J showed great decrease e ects on the number of infected human population. In the cost-e ectiveness of the control strategies, the results suggest that in the presence of limited resources, policy makers may adopt the strategy I (combination of the prevention, treatment and snail control) over J which includes additional cost of controlling loss of immunity. Finally, the model further suggested future opportunity for modi cation and re nement for the prediction of the e ects of climate variability on the transmission dynamics of Schistosoma.

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