Changes in Plasmodium Falciparum Population Dynamics in Two Populations at Different Time Periods in Ibadan, South-west Nigeria

Abstract

Changing the malaria epidemiology will affect the genetic diversity of Plasmodium falciparum. We studied the association between diversity at the merozoite surface protein 2 loci and the severity of disease in childhood malaria in two populations and at different time periods in Ibadan, southwest Nigeria. Population A comprised of 164 children (75 acute uncomplicated malaria (UM), 48 cerebral malaria (CM) and 41 severe malarial anaemia (SMA), while Population B comprised of 225 children (115 UM, 55 CM, 55 SMA). Results showed a high level of genetic diversity and multiplicity of P.falciparum infections in the two populations. Polyinfections were common in the 2 populations but different (93% for PA and 52% for PB), the mean multiplicity of infections was different (3.98 per infected person for Population A and 1.80 for Population B. The presence of polyinfections was significantly lower only in the SMA group in Population A, p=0.007 but significantly lower in the CM, p=0.003 and SMA groups, p=0.000 in Population B. The presence of FC27 and 3D7 alleles was a significant predictor of SMA in Population A but not in Population B. The absence of polyinfections (single infections) was found to be a strong common factor or predictor of severe malaria in the two populations. We conclude that presence of single infections are associated with the development of severe malaria. In addition, malaria control activities have a great impact on the changing parasite population dynamics.

Key words: msp2, Plasmodium falciparum, severe malaria, genetic diversity