The global distribution of the Duffy blood group
As a background to discussing the Duffy antigen in relation to malaria, a brief overview of malaria back to the mosquito when the mosquito takes a blood meal. The ability of the malaria parasite Plasmodium vivax to invade eryth- rocytes is Duffy blood group antigen through its Duffy-binding protein 1 (DBP1). To determine if . patients). DBP2 of P. vivax Structurally Related to DBP1 Binds Duffy-Null through the mosquito midgut epithelial cells without being. Human genetic resistance to malaria refers to inherited changes in the DNA of humans which . There is a negative correlation between frequencies of HbS and .. 72% of the island population were found to be Duffy-negative. there are enough Duffy-positive people to maintain mosquito transmission and liver infection.
Therefore, pyruvate kinase deficiency can cause hemolytic anemia. There is a significant correlation between severity of PK deficiency and extent of protection against malaria. Elliptocytosis Elliptocytosis a blood disorder in which an abnormally large number of the patient's erythrocytes are elliptical.
There is much genetic variability amongst those affected. There are three major forms of hereditary elliptocytosis: Southeast Asian ovalocytosis[ edit ] Main article: Southeast Asian ovalocytosis stained red blood cell membrane proteins on electrophoresis gel strip  Ovalocytosis is a subtype of elliptocytosis, and is an inherited condition in which erythrocytes have an oval instead of a round shape.
Several abnormalities of SAO erythrocytes have been reported, including increased red cell rigidity and reduced expression of some red cell antigens. There is a deletion of codons — in the gene, leading to a deletion of 9 amino-acids at the boundary between the cytoplasmic and transmembrane domains of band 3 protein.
Ovalocyte band 3 binds more tightly than normal band 3 to ankyrin, which connects the membrane skeleton to the band 3 anion transporter. These qualitative defects create a red blood cell membrane that is less tolerant of shear stress and more susceptible to permanent deformation. Red Blood Cell membrane major proteins SAO is associated with protection against cerebral malaria in children because it reduces sequestration of erythrocytes parasitized by P. Higher efficiency of sequestration via CD36 in SAO individuals could determine a different organ distribution of sequestered infected red blood cells.
These provide a possible explanation for the selective advantage conferred by SAO against cerebral malaria. Duffy antigen system Plasmodium vivax has a wide distribution in tropical countries, but is absent or rare in a large region in West and Central Africa, as recently confirmed by PCR species typing. However, observations have accumulated showing that the original Miller report needs qualification. In human studies of P. Genotyping indicated that multiple P. The authors suggest that among Malagasy populations there are enough Duffy-positive people to maintain mosquito transmission and liver infection.
More recently, Duffy negative individuals infected with two different strains of P. The frequency of such transmission is still unknown.
The same phenomenon has been observed in New World monkeys. The distribution of Duffy negativity in Africa does not correlate precisely with that of P. The potency of P. DARC negativity remains a good example of innate resistance to an infection, but it produces a relative and not an absolute resistance to P. Old World distribution of enzymopathies and immunogenetic variants Gerbich antigen receptor negativity[ edit ] Main article: Gerbich antigen system The Gerbich antigen system is an integral membrane protein of the erythrocyte and plays a functionally important role in maintaining erythrocyte shape.
The disease is transmitted through the bite of female Anopheles mosquitoes, even though in certain situations other mechanisms are possible. Additionally they are receptors for the chemokine family involved in the regulation of inflammatory processes. This resistance appears to have significantly influenced the distribution of Duffy system phenotypes in areas where malaria is endemic.
Human genetic resistance to malaria
The etiologic agent, Plasmodium sp. Malaria is caused by infestation of different species of protozoa of the genus Plasmodium: Mortality was also reduced from 3 deaths per 10, cases in to 1. In this same period, there was a considerable change in the transmission dynamics of malaria with concentrations of cases in specific municipalities. The number of municipalities at high risk, i. Sporadic autochthonic cases occurred in restricted focal areas. Often, infant mortality and morbidity are related to delay in establishing the correct diagnosis because of few clinical features.
Duffy Blood Group System and the malaria adaptation process in humans
This promotes the fertilization process producing zygotes that become invasive and grow and divide thus producing thousands of invasive sporozoites. These migrate through the body and invade the salivary glands of female mosquitoes. Females, when they feed again, inoculate sporozoites in the blood of man, which rapidly migrate into hepatocytes and transform into trophozoites in the liver where they mature and divide to form thousands of merozoites.
The liver cells rupture releasing merozoites into the circulation, thereby initiating the blood cycle. In this phase, symptoms do not appear in the host. In the blood cycle, the merozoites develop into trophozoites forming schizonts.
This stage of the cycle is associated with clinical symptoms. After a period of asexual replication, some merozoites differentiate into gametocytes and become infective to mosquitoes.