Malaria resistance (Duffy type)

Malaria resistanceGenetic testing and malaria resistance (Duffy antigen)

Malaria is one of the most common infectious diseases, infecting about 200 million people annually. It is widespread in tropical and subtropical regions, including parts of the Americas, Asia and Africa. It is an enormous health problem as two to three million people, mostly children under 5 years of age, die annually from malaria.

Malaria type Duffy represents more than 50 percent of all annual cases of malaria. Fortunately, it is the milder and usually not life-threatening form. Malaria type Duffy is a result of an infection with one of two types of protozoa of the genus Plasmodium (vivax, knowlesi). But malaria is caused also by three other types of parasites: ovale, malariae, and falciparum. The latter is the leading cause of malaria connected mortality as it causes the most severe form of the disease. Despite the fact that malaria can "only" cause fever, nausea and flu-like simptoms, do not underestimate any of the types of the disease, because with improper action you can risk serious complications, regardless of the cause.

Bite of a mosquito from genus Anopheles infects us indirectly

Plasmodium vivax malaria parasite infects first the female Anopheles mosquito that transmits the infection to humans. Plasmodium then forms a protein called PvDVP that binds to a specific antigen, called Duffy antigen. Such antigens are encountered quite commonly in our red blood cells and they form the Duffy antigen system, which is similar to the AB0 blood group system. Duffy positive people have these antigens, while blood cells of Duffy negative people are absent of these antigens.

Plasmodium vivax needs Duffy proteins to enter the red blood cells and subsequently develop the infection. Consequently, Duffy-negative individuals are resistant to malaria. As there are no antigens on the surface of red blood cells, through which the parasite infects them, the infection with this parasite is not possible.

The vast majority Caucasians (whites) are Duffy-positive and the absence of Duffy antigen is more common in Africans and inhabitants of Papua New Guinea. Probably, at some point in evolution, a mutation occurred, giving people a better chance of survival. People with a mutation were most likely to survive, leading to a retained mutation in the population. Duffy negative heterozygotes are individuals who have twice as little Duffy antigens, since this is in accordance with the genetic makeup of the gene DARC. Heterozygosity does not provide reliable resistance, but still leads to a reduced susceptibility to infection.