Assessing the impact of adverse reactions associated with ivermectin on the dynamics of onchocerciasis in the Democratic Republic of Congo

Ivermectin is the mainstay of onchocerciasis control. However, it has been discovered that it can induce severe adverse reactions in some individuals. Hence, this model is used to assess the impact of adverse reactions that may occur upon uptake of ivermectin on the control of onchocerciasis. Numerical study of the model shows that the fraction of infectious humans who may refuse to continue with treatment due to the experience of a severe adverse effect as well as the severe adverse reaction induced death rate has significant impact on the dynamics of the model. The adverse reaction induced death rate of infectious humans who may refuse to continue with treatment due to the experience of a severe adverse effect was shown to cause a backward bifurcation. Also, an increase in the fraction of infectious humans who may refuse to continue with treatment due to the experience of an adverse drug effect was shown to increase the backward bifurcation range. Numerical simulation of the optimal control model show that the use of both mass administration of ivermectin and vector control strategies will accelerate the achievement of onchocerciasis elimination.