title: Pregnant women are a reservoir of malaria transmission in Blantyre, Malawi.
abstract: BACKGROUND
  During pregnancy, women living in malaria-endemic regions are at increased risk of malaria infection and can harbour chronic placental infections. Intermittent preventive treatment with sulphadoxine-pyrimethamine (SP-IPTp) is administered to reduce malaria morbidity. It was hypothesized that the presence of placental malaria infection and SP-IPTp use would increase the risk of peripheral blood gametocytes, the parasite stage that is transmissible to mosquitoes. This would suggest that pregnant women may be important reservoirs of malaria transmission.
  
  
  METHODS
  Light microscopy was used to assess peripheral gametocytaemia in pregnant women enrolled in a longitudinal, observational study in Blantyre, Malawi to determine the association between placental malaria and maternal gametocytaemia. The relationship between SP-IPTp and gametocytaemia was also examined.
  
  
  RESULTS
  2,719 samples from 448 women were analysed and 32 episodes of microscopic gametocytaemia were detected in 27 women. At the time of enrolment 22 of 446 women (4.9%) had gametocytaemia and of the 341 women for whom there was sufficient sampling to analyse infection over the entire course of pregnancy, 27 (7.9%) were gametocytaemic at least once. Gametocytaemia at enrollment was associated with placental malaria, defined as malaria pigment or parasites detected by histology or qPCR, respectively (OR: 32.4, 95% CI: 4.2-250.2), but was not associated with adverse maternal or foetal outcomes. Administration of SP-IPTp did not affect gametocyte clearance or release into peripheral blood.
  
  
  CONCLUSIONS
  Gametocytaemia is present in 5% of pregnant women at their first antenatal visit and associated with placental malaria. SP-IPTp does not alter the risk of gametocytaemia. These data suggest that pregnant women are a significant reservoir of gametocyte transmission and should not be overlooked in elimination efforts. Interventions targeting this population would benefit from reaching women prior to first antenatal visit.
authors.affiliation: Center for Vaccine Development, School of Medicine, University of Maryland, Baltimore, MD, USA. sarah.boudova@som.umaryland.edu.
authors.forename: Sarah
authors.initials: S
authors.lastname: Boudová
authors.forename: Lauren M
authors.initials: LM
authors.lastname: Cohee
authors.forename: Linda
authors.initials: L
authors.lastname: Kalilani-Phiri
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Thesing
authors.forename: Steve
authors.initials: S
authors.lastname: Kamiza
authors.forename: Atis
authors.initials: A
authors.lastname: Muehlenbachs
authors.forename: Terrie E
authors.initials: TE
authors.lastname: Taylor
authors.forename: Miriam K
authors.initials: MK
authors.lastname: Laufer
mesh_terms: D000328:Adult; D000962:Antimalarials / Q000627:therapeutic use; D001769:Blood / Q000469:parasitology; D004197:Disease Reservoirs; D018562:Disease Transmission, Infectious; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008288:Malaria / Q000188:drug therapy / Q000453:epidemiology* / Q000635:transmission*; D008295:Malawi / Q000453:epidemiology; D008853:Microscopy; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D000962:Antimalarials