Allelic diversity of MSP1 and MSP2 repeat loci correlate with levels of malaria endemicity in Senegal and Nigerian populations

Abstract

Background Characterizing the genetic diversity of malaria parasite populations in different endemic settings (from low to high) could be helpful in determining the effectiveness of malaria interventions. This study compared Plasmodium falciparum parasite population diversity from two sites with low (pre-elimination) and high transmission in Senegal and Nigeria, respectively. Methods Parasite genomic DNA was extracted from 187 dried blood spot collected from confirmed uncomplicated P. falciparum malaria infected patients in Senegal (94) and Nigeria (93). Allelic polymorphism at merozoite surface protein 1 (msp1) and merozoite surface protein- 2 (msp2) genes were assessed by nested PCR. Results The most frequent msp1 and msp2 allelic families are the K1 and IC3D7 allelotypes in both Senegal and Nigeria. Multiplicity of infection (MOI) of greater that 1 and thus complex infections was common in both study sites in Senegal (Thies:1.51/2.53; Kedougou:2.2/2.0 for msp1/2) than in Nigeria (Gbagada: 1.39/1.96; Oredo: 1.35/1.75]). The heterozygosity of msp1 gene was higher in P. falciparum isolates from Senegal (Thies: 0.62; Kedougou: 0.53) than isolates from Nigeria (Gbagada: 0.55; Oredo: 0.50). In Senegal, K1 alleles was associated with heavy than with moderate parasite density. Meanwhile, equal proportions of K1 were observed in both heavy and moderate infection types in Nigeria. The IC3D7 subtype allele of the msp2 family was the most frequent in heavily parasitaemic individuals from both countries than in the moderately infected participants. Conclusion The unexpectedly low genetic diversity of infections high endemic Nigerian setting compared to the low endemic settings in Senegal is suggestive of possible epidemic outbreak in Nigeria.

Low genetic diversity of Plasmodium falciparum merozoite surface protein 1 and 2 and multiplicity of infections in western Ethiopia following effective malaria interventions

“…Examples of these include Senegal and Eswatini, which are now heading towards pre-elimination. Though high MOI and genetic diversity have been associated with higher malaria-endemicity, these indices as determined by msp1 and msp2 typing may not be sensitive enough at a lower overall transmission level as seen in Ethiopia [ 12 , 41 , 50 , 51 ]. However, the lack of differences with the relative variance in transmission intensities might be an indication that malaria control measures that reduce entomological inoculation rate [ 52 , 53 ], and deployment of artemisinin-combination therapy that reduce population diversity by removing the drug-sensitive parasites [ 54 ] have been effective in Ethiopia.…”

Temporal dynamics of Plasmodium falciparum population in Metehara, east-central Ethiopia

“…A study [49] that examined the genetic diversity of P. falciparum within a household in north-central Nigeria, reported remarkable degree of genetic diversity and polyclonal infections. Further study that analysed P. falciparum isolates from Nigeria and Senegal found K1 and IC/3D7 to be the most frequent msp1 and msp2 allelic families in both countries [50]. MOI was over 1 showing the widespread presence of polyclonal infections in both countries although more commonly in Senegal than in Nigeria.…”

Low genetic diversity of Plasmodium falciparum merozoite surface protein 1 and 2 and multiplicity of infections in western Ethiopia following effective malaria interventions

“…Examples of these include Senegal and Eswatini, which are now heading towards pre-elimination. Though high MOI, and genetic diversity has been associated with higher malaria-endemicity, these indices as determined by msp1 and msp2 typing may not be sensitive enough at a lower overall transmission level as seen in Ethiopia (12,35,45,46). However, the lack of differences with the relative variance in transmission intensities might be an indication that malaria control measures that reduce entomological inoculation rate (47,48), and deployment of artemisinin-combination therapy that reduce population diversity by removing the drug sensitive parasites (49) have been effective in Ethiopia.…”