Modeling HIV/AIDS transmitted heterosexually and from poor clinical settings in individuals with varied economic status

A model for heterosexual transmission for HIV/AIDS in two social classes, namely”the poor and the rich” including transmission from poor clinical settings, is formulated and analysed. Four sub-models are formulated and the disease threshold parameters are computed, for which the disease will died down or persist. Stability (local and global) of both the disease-free and endemic equilibria are investigated using various techniques of dynamical systems such as Lyapunov second method and the Center Manifold theory. To assess the impact of related HIV transmission from poor clinical settings, analysis on the bifurcation parameter was carried out, and we observed that increasing the rate of transmission of HIV through poor clinical settings increases the likelihood of occurrence of backward bifurcation which in turn makes it difficult to control the spread of the disease. The public health implication of this phenomenon (backward bifurcation) is that the classical requirement of having the reproduction number or disease threshold parameter less than unity, although necessary, is no longer sufficient for curtailing the outbreak of the disease. Model parameters were estimated based on the HIV/AIDS/STI Surveillance Report from National AIDS Control Programme of Tanzania. These values were then used to numerically simulate the model. Contrary to popular belief, results show that HIV seems to be most present in rich communities, but develop faster in poor individuals, and consequently increasing the number of AIDS cases and deaths in poor communities. Consequently, improving the conditions in clinical settings and starting massive educational campaign of health care workers on the risk of clinical transmission of HIV, and encouraging positive behavioural change through condom usage and abstinence from sexual activity of infected individuals can greatly reduce the number of outbreaks and the size of the epidemic in both social communities.