Climate Dependent Malaria Disease Transmission Model and its Analysis

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Date

2018-01-05

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Addis Ababa University

Abstract

The impact of climate change on human health, particularly through the potential increase in vector- and water-borne diseases, has received increasing attention in recent years. Environmental variables are known to a_ect signi_cantly the population dynamics and abundance of insects major catalysts of vector-borne diseases, but the exact extent and consequences of this sensitivity are not yet well-established. Malaria infection continues to be a major problem in many parts of the world including Africa. We focus here on mathematical model that describes the impact of climate variation on the malaria dynamics. To study this relation, a non-autonomous deterministic model is designed by incorporating the e_ect of both temperature and rainfall to the dispersion and mortality rate of adult mosquitoes and this is used to assess the impact of the variability in temperature and rainfall on the transmission dynamics of malaria in a population. In the model, the periodic variation of seasonal variables as well as the non-periodic variation due to the long term climate variation has been incorporated and analysed. In both cases, it has been shown that the disease-free solution of the model is globally asymptotically stable when the basic reproduction ratio is less than unity in the periodic system and when the threshold function is less than unity in the nonperiodic system. The disease is uniformly persistent when the basic reproduction ratio is greater than unity in the periodic system and when the threshold function is greater than unity with some additional conditions in the non-periodic system. The model has been validated using epidemiological data collected from western region of Ethiopia, by considering the trends for monthly number of microscopically con_rmed cases of malaria during the years 2000-2012 and the climate variation in the region. Then time dependent optimal control theory in the non periodic environment is applied to investigate optimal strategies for controlling the spread of malaria disease using insecticide treated bed nets, spray of mosquito insecticide and treatment as the system time dependent control variables. The possible impact of using combinations of two controls or one at a time on the spread of the disease is also examined.

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Asymptotic Stability, Periodic and Non-Periodic Climate Dependent Growth Rates, Validation Using Epidemiological Data, Time Dependent Optimal Control

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