title: Reduced prevalence of placental malaria in primiparae with blood group O.
abstract: BACKGROUND
  Blood group O protects African children against severe malaria and has reached high prevalence in malarious regions. However, its role in malaria in pregnancy is ambiguous. In 839 delivering Ghanaian women, associations of ABO blood groups with Plasmodium falciparum infection were examined.
  
  
  METHODS
  Plasmodium falciparum infection was diagnosed in placental blood samples by microscopy and PCR assays. Present or past infection was defined as the detection of parasitaemia or haemozoin by microscopy, or a positive PCR result. Blood groups were inferred from genotyping rs8176719 (indicating the O allele) and rs8176746/rs8176747 (distinguishing the B allele from the A allele).
  
  
  RESULTS
  The majority of women had blood group O (55.4%); present or past P. falciparum infection was seen in 62.3% of all women. Among multiparae, the blood groups had no influence on P. falciparum infection. In contrast, primiparae with blood group O had significantly less present or past infection than women with non-O blood groups (61.5 vs 76.2%, P = 0.007). In multivariate analysis, the odds of present or past placental P. falciparum infection were reduced by 45% in blood group O primiparae (aOR, 0.55 [95% CI, 0.33-0.94]).
  
  
  CONCLUSIONS
  The present study shows a clear protective effect of blood group O against malaria in primiparae. This accords with findings in severe malaria and in vitro results. The data underline the relevance of host genetic protection among primiparae, i.e. the high-risk group for malaria in pregnancy, and contribute to the understanding of high O allele frequencies in Africa.
authors: George
authors: G
authors: Bedu-Addo
authors: Prabhanjan P
authors: PP
authors: Gai
authors: Stefanie
authors: S
authors: Meese
authors: Teunis A
authors: TA
authors: Eggelte
authors: Kumarasamy
authors: K
authors: Thangaraj
authors: Institute of Tropical Medicine and International Health, Charité - University Medicine Berlin, Berlin, Germany. frank.mockenhaupt@charite.de.
authors: Frank P
authors: FP
authors: Mockenhaupt
mesh_terms: D000017:ABO Blood-Group System / Q000502:physiology*; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000453:epidemiology; D016017:Odds Ratio; D010298:Parity; D010922:Placenta Diseases / Q000097:blood / Q000453:epidemiology; D010963:Plasmodium falciparum; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000097:blood / Q000453:epidemiology
chemical_list: D000017:ABO Blood-Group System