title: Placental Plasmodium falciparum malaria infection: operational accuracy of HRP2 rapid diagnostic tests in a malaria endemic setting.
abstract: BACKGROUND
  Malaria has a negative effect on the outcome of pregnancy. Pregnant women are at high risk of severe malaria and severe haemolytic anaemia, which contribute 60-70% of foetal and perinatal losses. Peripheral blood smear microscopy under-estimates sequestered placental infections, therefore malaria rapid diagnostic tests (RDTs) detecting histidine rich protein-2 antigen (HRP-2) in peripheral blood are a potential alternative.
  
  
  METHODS
  HRP-2 RDTs accuracy in detecting malaria in pregnancy (MIP >28 weeks gestation) and placental Plasmodium falciparum malaria (after childbirth) were conducted using Giemsa microscopy and placental histopathology respectively as the reference standard. The study was conducted in Mbale Hospital, using the midwives to perform and interpret the RDT results. Discordant results samples were spot checked using PCR techniques.
  
  
  RESULTS
  Among 433 febrile women tested, RDTs had a sensitivity of 96.8% (95% CI 92-98.8), specificity of 73.5% (95% CI 67.8-78.6), a positive predictive value (PPV) of 68.0% (95% CI 61.4-73.9), and negative predictive value (NPV) of 97.5% (95% CI 94.0-99.0) in detecting peripheral P. falciparum malaria during pregnancy. At delivery, in non-symptomatic women, RDTs had a 80.9% sensitivity (95% CI 57.4-93.7) and a 87.5% specificity (95%CI 80.9-92.1), PPV of 47.2% (95% CI 30.7-64.2) and NPV of 97.1% (95% CI 92.2-99.1) in detecting placental P. falciparum infections among 173 samples. At delivery, 41% of peripheral infections were detected by microscopy without concurrent placental infection. The combination of RDTs and microscopy improved the sensitivity to 90.5% and the specificity to 98.4% for detecting placental malaria infection (McNemar's X(2)> 3.84). RDTs were not superior to microscopy in detecting placental infection (McNemar's X(2)< 3.84). Presence of malaria in pregnancy and active placental malaria infection were 38% and 12% respectively. Placental infections were associated with poor pregnancy outcome [pre-term, still birth and low birth weight] (aOR = 37.9) and late pregnancy malaria infection (aOR = 20.9). Mosquito net use (aOR 2.1) and increasing parity (aOR 2.7) were associated with lower risk for malaria in pregnancy.
  
  
  CONCLUSIONS
  Use of HRP-2 RDTs to detect malaria in pregnancy in symptomatic women was accurate when performed by midwives. A combination of RDTs and microscopy provided the best means of detecting placental malaria. RDTs were not superior to microscopy in detecting placental infection. With a high sensitivity and specificity, RDTs could be a useful tool for assessing malaria in pregnancy, with further (cost-) effectiveness studies.
authors: Malaria Consortium, Upper Naguru East Road, P,O, Box 8045, Kampala, Uganda. drdjkyabayinze@yahoo.com
authors: Daniel J
authors: DJ
authors: Kyabayinze
authors: James K
authors: JK
authors: Tibenderana
authors: Mercy
authors: M
authors: Nassali
authors: Lynette K
authors: LK
authors: Tumwine
authors: Clare
authors: C
authors: Riches
authors: Mark
authors: M
authors: Montague
authors: Helen
authors: H
authors: Counihan
authors: Prudence
authors: P
authors: Hamade
authors: Jean-Pierre
authors: JP
authors: Van Geertruyden
authors: Sylvia
authors: S
authors: Meek
mesh_terms: D000293:Adolescent; D000328:Adult; D000953:Antigens, Protozoan / Q000097:blood*; D001769:Blood / Q000469:parasitology; D019411:Clinical Laboratory Techniques / Q000379:methods*; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000469:parasitology; D008853:Microscopy; D010922:Placenta Diseases / Q000175:diagnosis* / Q000469:parasitology; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000175:diagnosis*; D015800:Protozoan Proteins / Q000097:blood*; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000953:Antigens, Protozoan; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins