Abstract:
Background: Genetic diversity in Plasmodium falciparum populations can be used to describe the resilience and
spatial distribution of the parasite in the midst of intensified intervention efforts. This study used microsatellite
analysis to evaluate the genetic diversity and population dynamics of P. falciparum parasites circulating in three
ecological zones of Ghana.
Methods: A total of 1168 afebrile children aged between 3 to 13 years were recruited from five (5) Primary schools
in 3 different ecological zones (Sahel (Tamale and Kumbungu), Forest (Konongo) and Coastal (Ada and Dodowa)) of
Ghana. Asymptomatic malaria parasite carriage was determined using microscopy and PCR, whilst fragment analysis
of 6 microsatellite loci was used to determine the diversity and population structure of P. falciparum parasites.
Results: Out of the 1168 samples examined, 16.1 and 39.5% tested positive for P. falciparum by microscopy and
nested PCR respectively. The genetic diversity of parasites in the 3 ecological zones was generally high, with an
average heterozygosity (He) of 0.804, 0.787 and 0.608 the rainy (peak) season for the Sahel, Forest and Coastal zones
respectively. The mean He for the dry (off-peak) season were 0.562, 0.693 and 0.610 for the Sahel, Forest and Coastal
zones respectively. Parasites from the Forest zone were more closely related to those from the Sahel than from the
Coastal zone, despite the Coastal zone being closer in physical distance to the Forest zone. The fixation indexes
among study sites ranged from 0.049 to 0.112 during the rainy season and 0.112 to 0.348 during the dry season.
Conclusion: A large asymptomatic parasite reservoir was found in the school children during both rainy and dry
seasons, especially those in the Forest and Sahel savannah zones where parasites were also found to be related
compared to those from the Coastal zone. Further studies are recommended to understand why despite the roll
out of several malaria interventions in Ghana, high transmission still persist.
