Genetic polymorphism of Plasmodium falciparum isolates based on the merozoite surface protein 1 and 2 (msp-1 and msp-2) genes as a molecular marker in Oveng and Mintom, South Cameroon

Background Malaria remains a critical public health issue in Cameroon, where Plasmodium falciparum is the predominant species responsible for severe clinical cases. Investigating the genetic diversity and multiplicity of infection (MOI) of P. falciparum is essential for understanding transmission dynamics, immune evasion, and the effectiveness of control strategies. This study aimed to characterize the allelic polymorphism and MOI of P. falciparum isolates collected in Oveng and Mintom, two malaria-endemic areas in southern Cameroon. Methods Genomic DNA was extracted from dried blood spots collected from infected individuals. P. falciparum detection and species confirmation were performed using a multiplex polymerase chain reaction (PCR). Genotyping of msp1 (allelic families: KI, MAD20, RO33) and msp2 (allelic families: FC27, 3D7) was conducted via nested PCR. Fragment analysis was used to determine allelic variants and estimate MOI. Results A total of 315 P. falciparum isolates were successfully amplified and genotyped. For msp1 , 12 distinct alleles were identified (3 for KI, 7 for MAD20, and 2 for RO33), with fragment sizes ranging from 172 to 300 bp. For msp2 , 28 alleles were detected (14 for each FC27 and 3D7allelic families), with fragment sizes ranging from 200 to 800 bp. FC27 was the most prevalent allelic family (100%), followed by 3D7 (98.4%), MAD20 (75.2%), and RO33 (74.9%). The number of clones per infection ranged from 1 to 7, with 99% of samples exhibiting polyclonal infections. The mean MOI was significantly higher for msp2 compared to msp1 (4.85 vs. 2.40; P  < 0.05). Expected heterozygosity was 0.83 for msp1 and 0.98 for msp2 , indicating high genetic diversity. Conclusion The observed high allelic diversity and elevated MOI among P. falciparum isolates suggest intense malaria transmission in the study areas. These findings underscore the need to strengthen local malaria control interventions and provide valuable baseline data for future surveillance and vaccine development efforts.