The diversity of Plasmodium falciparum isolates from asymptomatic and symptomatic school-age children in Kinshasa province, Democratic Republic of Congo

Abstract

Background. Understanding Plasmodium falciparum population diversity and transmission dynamics provides information on the intensity of malaria transmission, which is needed for assessing malaria control interventions. We investigated P. falciparum allelic diversity and multiplicity of infection (MOI) in asymptomatic and symptomatic school-age children in Kinshasa province, Democratic Republic of Congo (DRC). Methods. A total of 438 DNA samples (248 asymptomatic and 190 symptomatic) were characterized by nested PCR and genotyping the polymorphic regions of pfmsp1 block 2 and pfmsp2 block 3. Results. Nine allele types were observed in pfmsp1 block2. The K1-type allele was predominant with 78% (229/293) prevalence, followed by the MAD20-type allele (52%, 152/293) and RO33-type allele (44%, 129/293). Twelve alleles were detected in pfmsp2; and the 3D7-type allele was the most frequent with 84% (256/304) prevalence, followed by the FC27-type allele (66%, 201/304). Polyclonal infections were detected in 63% (95% CI: 56, 69) of the samples, and the MOI was 2.0 (95% CI: 1.9, 2.1) in P. falciparum single species infections. MOIs significantly increased in Plasmodium falciparum isolates from symptomatic parasite carriers than asymptomatic ones (2.24 versus 1.69, Adjusted b: 0.36, (95% CI: 0.01, 0.72), p = 0.046) and parasitemia >10,000 parasites/µL compared to parasitemia <5,000 parasites/µL (2.68 versus 1.63, Adjusted b: 0.89, (95% CI: 0.46, 1.25), p < 0.001). Conclusion. Our survey showed low allelic diversity and MOI of P. falciparum, which reflects a moderate intensity of malaria transmission in the study areas. MOIs were more likely to be common in symptomatic infections and increased with the parasitemia level. Further studies in different transmission zones are needed to understand the epidemiology and parasite complexity in the DRC.