EXTENSIVE GENETIC DIVERSITY OF PLASMODIUM-FALCIPARUM ISOLATES COLLECTED FROM PATIENTS WITH SEVERE MALARIA IN DAKAR, SENEGAL

While some genetic host factors are known to protect against severe Pl asmodium falciparum malaria, little is known about parasite virulence factors. We have compared the generic characteristics of P. falciparum isolates collected from 56 severe malaria patients and from 30 mild m alaria patients recruited in Hopital Principal, Dakar, Senegal. All is olates were typed using polymerase chain reaction amplification of pol ymorphic genetic loci (MSP-1, MSP-2, HRP1, GLURP, CSP, RESA, and the m ultigene family Pf60). The complexity of infections was lower in sever s than in mild malaria and the parasite genetic diversity in both grou ps was very large. No specific genetic make-up was associated with sev erity; there were, however, marked differences in allele frequencies i n both groups, with a prevalence up to 60% of MSP-2 alleles specifical ly observed in the severe malaria isolates. In addition, the presence of MSP-1/RO33 alleles was significantly associated with a higher plasm a level of tumour necrosis factor a receptor 1 (P<0.05), a reported in dicator of severity in human malaria. These results point to potential differences in the genetic characteristics of parasites inducing seve re versus mild pathology.