Malaria is the vector-transmitted disease that causes the highest
morbidity and mortality in humans. Motivated by the known influence
of sickle-cell anemia on the morbidity and mortality of
we study the effect of malaria on the genetic composition of a host (human) population where
sickle-cell anemia is prevalent and malaria is endemic. The host subpopulations are therefore
classified according to three genotypes, $A$$A$, $AS$, and $SS$. It is known that $A$$A$ malaria-infected
individuals experience higher malaria-induced mortality than $AS$ or $SS$ individuals. However,
individuals carrying the $S$ gene are known to experience a higher mortality rate in a malaria-free
environment than those who lack such a gene. The tradeoffs between increased fitness for some types
in the presence of disease (a population level process) and reduced fitness in a disease-free environment
are explored in this manuscript. We start from the published results of an earlier model and proceed to
remove some model restrictions in order to better understand the impact on the natural hosts' genetics
in an environment where malaria is endemic.
Mathematics Subject Classification: 92D15, 92D25, 92D30, 34C60, 34D15.