Continuous and pulsed epidemiological models for onchocerciasis with implications for eradication strategy

Area of Science:

• Epidemiology
• Mathematical Modeling
• Public Health

Background:

• Onchocerciasis is a significant endemic disease in sub-Saharan Africa.
• Existing complex mathematical models for onchocerciasis eradication have shown limitations in predicting real-world outcomes.
• The immunological complexity of onchocerciasis hinders accurate modeling of eradication strategies.

Purpose of the Study:

• To simplify mathematical models for onchocerciasis by incorporating a single empirical parameter for immunological aspects.
• To analyze the efficacy of continuous versus intermittent treatment strategies for onchocerciasis eradication.
• To develop simplified model criteria for achieving disease elimination.

Main Methods:

• Reduced a vector-borne epidemiological model to an infectious disease model with nonlinear incidence using asymptotic approximation.
• Developed and analyzed two model versions: continuous treatment and pulsed (interval) treatment.
• Conducted thorough mathematical analysis to determine equilibrium and periodic solutions and conditions for endemic disease existence.

Main Results:

• The continuous treatment model serves as an excellent approximation for the more realistic pulsed treatment model.
• Analytical results and numerical experiments identified conditions for disease eradication.
• Current onchocerciasis eradication strategies are insufficient for high-incidence regions and progress too slowly even towards disease-free states.

Conclusions:

• Simplified mathematical models can effectively guide onchocerciasis eradication strategies.
• The findings highlight the inadequacy of current eradication efforts in the most affected areas.
• Revised strategies are necessary to accelerate onchocerciasis elimination, particularly in regions with the highest disease burden.