High Frequency of the Fyes Duffy Antigen Receptor for Chemokines Allele in the Absence of Plasmodium Vivax in Kilifi, Kenya

Abstract

Malaria is a human disease that is caused by the Plasmodium parasite and it is a life-threatening disease. Plasmodium vivax being one of the parasites among other Plasmodium parasites is a major cause in spreading malaria in humans. The other four parasites that affect the human species include Plasmodium falciparum, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi. Plasmodium vivax is predominant in the Asian and the American continents whereas Plasmodium falciparum is predominant in the African continent and is mainly being tackled along the coastal and western regions of Kenya. Plasmodium vivax is usually neglected in the African continent since it has been shown that the African population is negative for the Duffy blood-group antigen genotype with the presence of the FYES allele. Since this gene is silenced, it does not mediate invasion of erythrocytes by the Plasmodium vivax parasite. Due to the high prevalence of the absence of the Duffy blood-group antigen on the surface of the red blood cells, Plasmodium vivax is not highly considered as compared to Plasmodium falciparum which is highly prevalent in the African continent, especially in Kenya. This study was geared towards finding the frequency of the FYES allele in malaria patients from Kilifi County Hospital. Parasite genomic DNA was extracted from 204 blood samples. The DARC gene was amplified by Polymerase Chain Reaction (PCR). Samples that generated good amplicons were analysed by Restriction Fragment Length Polymorphism (RFLP) to validate whether the individuals being tested were Duffy positive or Duffy negative. The samples tested matched the pattern of the Duffy negative control. The samples were then tested for Plasmodium vivax infections using vivax primers and a positive control sample. All the samples were negative for P. vivax infections. In conclusion, P. vivax is not prevalent in the Kilifi region since the FYES allele is expressed at a high frequency in this region.