7th Call - Dr. Charles Brown

Project Title: Molecular Surveillance of Plasmodium vivax infection and Duffy genotypes in Ghana.

Principal Investigator: Dr. Charles Brown (Department of Medical Laboratory Sciences, SAHS, University of Ghana)

Email Address: cbrown@ug.edu.gh

Award Amount: GHC 24,953.00

Project Status: On-going

Summary:

Plasmodium vivax infection is not thought to be transmitted in western and central Africa, because of the very high prevalence of the red blood cell (RBC) Duffy-negative phenotype in local populations. The Duffy-negative phenotype is a condition which is thought to confer complete resistance against blood infection with P. vivax. However, recent studies from different malaria-endemic regions have now shown that P. vivax can infect RBCs and cause clinical disease in Duffy-negative people: in western Kenya, in the Western Brazilian Amazon region, in Madagascar, in African West Coast (Equatorial Guinea and Angola), and in Mauritania, north-west Africa. This suggests that the relationship between P. vivax and the Duffy antigen is more complex than customarily described. Some investigators have interpreted such findings to imply that the parasite may be in the process of evolving the ability to infect Duffy-negative individuals by using other receptors than Duffy to invade the erythrocytes. However,it has been argued that P. vivax transmission can be expected in populations with high levels of RBC Duffy negativity and in which malaria transmission intensities are sufficiently high, as it is in many disease endemic areas of western and central Africa. In a study published in 2012, it was reported that nested-PCR and DNA-sequence analyses of selected samples unequivocally confirmed the presence of P. vivax in Mali. An important limitation of this work was the inability to link such confirmed P. vivax infections with the Duffy and G6PD phenotypes of the individuals affected. Little is known about the distribution of Duffy phenotypes in Ghana. In addition, there is no information (to the best of our knowledge) on P. vivax infection, its prevalence and impact on public health. The study proposes to look at the presence of P. vivax infections in Duffy-negative individuals at selected sites across Ghana. It is expected that at the end of the study, human blood samples infected with P. vivax will be detected and the frequency of Duffy blood group and Duffy genotypes will be determined in any P. vivax human isolates.