Incorporating Heterogeneity in Malaria Models: Methods, Examples, and Implications

Heterogeneity in malaria transmission is a critical factor that influences the effectiveness of control strategies and the dynamics of disease spread. In this talk, I will address several key sources of heterogeneity in malaria models, including spatial, temporal, and age-related variations, particularly in light of the recent approval of the RTS,S malaria vaccine.
I will present two models: the first is an age-structured PDE malaria (P. falciparum) model that couples vector-host epidemiological dynamics with immunity dynamics. This model tracks the acquisition and loss of anti-disease immunity over time and examines its nonlinear feedback on transmission parameters. Motivated by the newly approved RTS,S vaccine, the model also investigates the impact of vaccination, revealing a reduction in severe disease among young children but a slight increase in severe malaria among older children due to delayed exposure and lower acquired immunity.

The second model addresses genetic heterogeneity in susceptibility to Plasmodium vivax malaria. It explores the role of the Duffy-negative genotype in modifying transmission dynamics, using a seasonal framework to track genotype changes and derive the basic reproduction number, $R_0$. Calibrated with data from the Amazonas region in Brazil, this model identifies the critical proportion of Duffy-negative individuals required to protect the population without additional interventions. It also assesses how different Duffy-negative proportions influence monthly P. vivax incidence, providing insights into the interaction between genetic resistance and malaria burden.