Modelling the transmission of Buruli ulcer in fluctuating environments

[摘要] ENGLISH ABSTRACT : Buruli ulcer is a disease caused by Mycobacterium ulcerans. The transmissiondynamics of this disease largely depends on environmental changes.In this thesis a deterministic model for the transmission converge to the disease free and endemic equilibrium respectively. A verygood synergy was obtained between the deterministic model and STELLAmodel. The STELLA model however, provided flexibility through its abilityto accommodate more social dynamics without adding mathematicalintractability. The model provides useful insights in the dynamics of Buruliulcer and has significant implication to the management of disease. of Buruli ulcer influctuating environments is proposed. The model incorporates periodicityin the disease transmission pathways and the Mycobacterium ulceransdensity, that are thought to vary seasonally. Two reproduction numbers,time-averaged reproduction number [R0] and the basic reproduction numberR0, are determined and compared. The time-averaged reproductionnumber obtained shows that Buruli ulcer epidemic is driven by the dynamicsof the environments. It shows inaccuracy in predicting the numberof infections. Numerical simulations confirmed that if R0 > 1 the infectionis sustained seasonally. The model outcome suggests that environmentalfluctuation should be taken into consideration in designing policies aimedat Buruli ulcer control and management. In addition to the deterministicmodel, a systems dynamic model for the transmission of Buruli ulcer byusing STELLA is also proposed with and without periodicity in the diseasetransmission pathways and the Mycobacterium ulcerans density. Themodel simulations confirm that when R0 < 1 and R0 > 1 the solutions converge to the disease free and endemic equilibrium respectively. A verygood synergy was obtained between the deterministic model and STELLAmodel. The STELLA model however, provided flexibility through its abilityto accommodate more social dynamics without adding mathematicalintractability. The model provides useful insights in the dynamics of Buruliulcer and has significant implication to the management of disease.

[发布机构] Stellenbosch University