Genetic Polymorphism of Merozoite Surface Protein-2 (MSP-2) in Plasmodium falciparum Isolates from Endemic Sub-Counties, A Case Study in Kisii County, Kenya

Background: Despite a lot of efforts being put in place globally to reduce malaria burden, malaria is still one of the major public health problem. P. falciparum analysis of the Msp2 gene gives paramount evidence in the evaluation of malaria epidemiology to assist in the ongoing malaria control and elimination programs. Therefore this study aimed at examining genetic polymorphism of msp-2 gene of P. falciparum and its multiplicity of infection (MOI) from endemic Sub-Counties in Kisii County, Kenya.

Methodology: Dried blood spots were collected from 249 study participants who were positive for P. falciparum parasite in endemic Sub – Counties in Kisii County from January to April 2021. Parasites density/μl of blood was calculated by multiplying the number of parasites counted and 8000 white cells/μl then dividing by number of white cells counted. Parasite level was considered low if the parasite/μl of blood was < 500, moderate 501 ≤ 5000 and high if it was > 5000 Parasites DNA was extracted using chelex-100® method and nested PCR for amplification followed by fragment analysis using gel electrophoresis.

Results: 246 samples were identified with msp2 alleles where 94% belonged to 3D7 and 83% belonged to FC27. 40 different polymorphic alleles were identified where 13 belonged to FC27 and 27 belonging to 3D7. 86% isolates had multiple msp2 alleles where the Multiplicity of infection (MOI) overall mean was 2.75.

Conclusion: The study isolates showed high genetic polymorphism. Therefore, this suggests that there is high local malaria transmission, meaning there is failure to the scale up of malaria control interventions in the endemic areas of the County.