The clinical outcome of Plasmodium falciparum infections ranges from asymptomatic parasitemia to severe malaria syndromes associated with high mortality. The virulence of P. falciparum infections is associated with the type of P. falciparum erythrocyte membrane protein 1 (PfEMP1) expressed on the surface of infected erythrocytes to anchor these to the vascular lining. Although var2csa, the var gene encoding the PfEMP1 associated with placental malaria, was discovered in 2003, the identification of the var/PfEMP1 variants associated with severe malaria in children has remained elusive. To identify var/PfEMP1 variants associated with severe disease outcome, we compared var transcript levels in parasites from 88 children with severe malaria and 40 children admitted to the hospital with uncomplicated malaria. Transcript analysis was performed by RT-quantitative PCR using a set of 42 primer pairs amplifying var subtype-specific loci covering most var/ PfEMP1 subtypes. In addition, we characterized the near-fulllength sequence of the most prominently expressed var genes in three patients diagnosed with severe anemia and/or cerebral malaria. The combined analysis showed that severe malaria syndromes, including severe anemia and cerebral malaria, are associated with high transcript levels of PfEMP1 domain cassette 8-encoding var genes. Transcript levels of group A var genes, including genes encoding domain cassette 13, were also significantly higher in patients with severe syndromes compared with those with uncomplicated malaria. This study specifies the var/PfEMP1 types expressed in severe malaria in children, and thereby provides unique targets for future efforts to prevent and treat severe malaria infections.

Alpha + -thalassaemia is well known for conferring partial protection to against severe malaria. On the other, Glutathione -S-transferase (GST) polymorphism has recently been associated to severe malaria in children. A retrospective cross sectional study was carried out to determine the relationship between genotypic polymorphisms of alpha + -thalassaemia and glutathione-S-transferase in children with severe malaria. A total of 148 DNA samples from children aged between 1 and 15 years with mild and severe malaria were retrieved and determined by polymerase chain reaction. Children with Glutathione-S-transferase-pi1 (GSTP1)-polymorphism were observed to have three fold risk (OR = 2.9; 95% CI =1.3-6.1; P = 0.006) of developing severe malaria compared to mild malaria in Mnyuzi-Korogwe, north-eastern, Tanzania. In the presence of Glutathione-S-transferase-pi1 polymorphism, children were found to have 3% decreased protective effect of alpha + -thalassaemia polymorphisms (homozygotes and heterozygotes) against severe malaria although this was not statistically significant [ OR = 0.81 (95% CI = 0.5-1.5; P = 0.5) to OR = 0.78 (95% CI = 0.4-1.5; P = 0.44)]. We conclude that Glutathione-S-transferase-pi1 polymorphism increases risk of developing severe malaria due to Plasmodium falciparum in children. The observed inverse relationship between GSTP1 polymorphisms and alpha + -thalassaemia to children with severe malaria need further investigation.