What are the host protective factors against malaria?

Updated: Apr 26, 2019
  • Author: Thomas E Herchline, MD; Chief Editor: Michael Stuart Bronze, MD  more...
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Answer

The sickle cell trait (hemoglobin S), thalassemias, hemoglobin C, and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency are protective against death from P falciparum malaria, with the sickle cell trait being relatively more protective than the other 3. Individuals with hemoglobin E may be protected against P vivax infection. A systematic review and meta-analysis analyzed the significance of some of these hemoglobinopathies and their protective effects against malaria. However, the degree of protection that these hemoglobinopathies confer is variable and they provide mild or no protection against uncomplicated malaria and asymptomatic parasitemia. [8]

Individuals who are heterozygotic for RBC band 3 ovalocytosis are at reduced risk of infection with P falciparum, P knowlesi, and, especially, P vivax malaria. West African populations lacking RBC Duffy antigen are completely refractory to infection by P vivax. Polymorphisms in a host’s TNF (tumor necrosis factor) gene can also be protective against malaria.

Persons living in areas of malaria endemicity may develop partial immunity to infection with time and repeated exposure. This limited immunity reduces the frequency of symptomatic malaria and also reduces the severity of infection. Immunity to malaria infection can be lost over long periods of time spent away from endemic areas with limited exposure. As a result, those individuals born in malaria-endemic regions who move abroad for work or study and then return home may be at increased risk for developing severe malaria and complications of infection.


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