Let’s summarize:
First, malaria is more serious in central Africa because the climate is a tropical rain forest climate, hot and humid, suitable for the survival of mosquitoes and other malaria parasite vectors.
Second, the public health system is lacking. Central Africa is a region where the world's least developed countries are concentrated, with per capita GDP generally less than US$800. Perennial famine and fiscal deficits have resulted in a serious lack of medical funding. Coupled with backward technology, malaria patients cannot be effectively isolated and treated, leading to large-scale transmission.
Another point is the problem of medicines. Quinine and other special medicines are difficult to buy locally, so most foreign travelers bring their own. You can imagine what the situation is on the ground.