title: Reduction of multiplicity of infections but no change in msp2 genetic diversity in Plasmodium falciparum isolates from Congolese children after introduction of artemisinin-combination therapy.
abstract: BACKGROUND
  In this first study conducted after the introduction of artemisinin-combination therapy (ACT), the major objective was to evaluate Plasmodium falciparum genetic diversity and multiplicity of infection in isolates from Congolese children between one and nine years of age enrolled and followed up for one year. The secondary objective was to characterize the msp2 profiles of P. falciparum isolates collected from successive malaria episodes in ten children who had four or more clinical episodes during the follow up.
  
  
  METHODS
  Three-hundred and thirteen children residing in southern part of Brazzaville participated in this study. Blood samples were obtained from all children at enrollment and checked for P. falciparum infection. Based on the one year follow-up data, two clinical groups were considered according to the number of malaria episodes presented over the follow up period: "protected"(children who did not experience any episode) and "unprotected" (those who experienced more that two episodes). Therefore, the msp2 genetic diversity of P. falciparum isolates collected at enrollment in the two groups was characterized by allele-specific nested PCR and compared. The msp2 profiles of P. falciparum isolates collected from successive malaria episodes was also characterized by allele-specific nested PCR.
  
  
  RESULTS
  Forty-three percent of FC27 and fifty-seven percent of 3D7 in protected vs fifty-six percent of FC27 and forty-four percent of 3D7 in isolates from unprotected children were detected. Seven and two alleles belonging to the FC27, and six and three alleles belonging to 3D7 families were distinguished in isolates from protected and unprotected children respectively. The mean multiplicity of infection (MOI) values at inclusion for the msp2 locus was 1.29 and 1.43 for protected and unprotected children respectively. 43 isolates were obtained from the ten children who had four or more clinical episodes during the follow up. A total of 63 alleles or fragments corresponding to 57% (36/63) FC27 and 43% (27/63) 3D7 were detected. The variant 400bp of FC27 was the most prevalent. 46% (20/43), 42% (18/43), 2% (1/43) and 2% (1/43) of isolates were found to have 1, 2, 3 and 4 parasite genotypes respectively and the mean MOI was 1.78.
  
  
  CONCLUSIONS
  This study shows that the introduction of ACT in the Republic of Congo has reduced the MOI but not the genetic diversity of P. falciparum isolates from children living in Southern districts of Brazzaville.
authors.affiliation: Fondation Congolaise pour la Recherche Médicale, Brazzaville, Republic of Congo.
authors.forename: Rod
authors.initials: R
authors.lastname: Ibara-Okabande
authors.forename: Felix
authors.initials: F
authors.lastname: Koukouikila-Koussounda
authors.forename: Mathieu
authors.initials: M
authors.lastname: Ndounga
authors.forename: Jeannhey
authors.initials: J
authors.lastname: Vouvoungui
authors.forename: Vladimir
authors.initials: V
authors.lastname: Malonga
authors.forename: Prisca Nadine
authors.initials: PN
authors.lastname: Casimiro
authors.forename: Jean Rosaire
authors.initials: JR
authors.lastname: Ibara
authors.forename: Anissa
authors.initials: A
authors.lastname: Sidibe
authors.forename: Francine
authors.initials: F
authors.lastname: Ntoumi
mesh_terms: D000953:Antigens, Protozoan / Q000235:genetics*; D000962:Antimalarials / Q000008:administration & dosage*; D037621:Artemisinins / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D003223:Congo / Q000453:epidemiology; D004359:Drug Therapy, Combination; D005787:Gene Frequency; D017125:Genes, Protozoan; D014644:Genetic Variation; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology / Q000469:parasitology*; D017720:Molecular Epidemiology; D010963:Plasmodium falciparum / Q000235:genetics* / Q000302:isolation & purification; D015800:Protozoan Proteins / Q000235:genetics*; D012008:Recurrence
chemical_list: D000953:Antigens, Protozoan; D000962:Antimalarials; D037621:Artemisinins; D015800:Protozoan Proteins; C065974:merozoite surface protein 2, Plasmodium; C031327:artemisinin