Genetic Diversity and Complexity of Plasmodium Falciparum Infections inLagos, Nigeria

Background: Genetic diversity in Plasmodium falciparum populations is of major importance in the outcome of antimalarial drug trialsand vaccine design. Merozoite surface protein-1 (msp 1) and msp 2 are well known antigenic markers for distinguishing persistent and new infections with P. falciparum. Methods: Parasite DNA was extracted from one hundred blood samples collected from patients confirmed by microscopy to be P. falciparum-positive followed by PCR-genotyping for msp 1 (block2) and msp 2 (block 3) allelic families. Results: All the families of msp 1 locus (K1, MAD20 and R033) and msp 2 (FC27 and 3D7) were observed. K1 was the most predominant msp 1 allelic family (60/100) followed by MAD20 (50/100) while R033 had the least frequency (45/100). In the msp 2 locus, FC27 showed higher frequency (62/100) than 3D7 (55/100). The allelic families existed alone and/or in combination with other families. However, no R033/MAD20 combination was observed. Multiplicity of Infection (MOI) with msp 1 was higher in Ikorodu (1.50) than in Lekki (1.39) while MOI with msp 2 was lower in Ikorodu (1.14) than in Lekki (1.76). There was however no significant difference in the mean MOI between the two study areas (P=0.427). Conclusion: The observation of limited parasite diversity may signal the need for the use of less subjective genotyping tools in distinguishing recrudescence and reinfections with P. falciparum during drug trials.