title: Asymptomatic Plasmodium falciparum malaria in pregnant women in the Chittagong Hill Districts of Bangladesh.
abstract: BACKGROUND
  Pregnancy is a known risk factor for malaria which is associated with increased maternal and infant mortality and morbidity in areas of moderate-high malaria transmission intensity where Plasmodium falciparum predominates. The nature and impact of malaria, however, is not well understood in pregnant women residing in areas of low, unstable malaria transmission where P. falciparum and P. vivax co-exist.
  
  
  METHODS
  A large longitudinal active surveillance study of malaria was conducted in the Chittagong Hill Districts of Bangladesh. Over 32 months in 2010-2013, the period prevalence of asymptomatic P. falciparum infections was assessed by rapid diagnostic test and blood smear and compared among men, non-pregnant women and pregnant women. A subset of samples was tested for infection by PCR. Hemoglobin was assessed. Independent risk factors for malaria infection were determined using a multivariate logistic regression model.
  
  
  RESULTS
  Total of 34 asymptomatic P. falciparum infections were detected by RDT/smear from 3,110 tests. The period prevalence of asymptomatic P. falciparum infection in pregnant women was 2.3%, compared to 0.5% in non-pregnant women and 0.9% in men. All RDT/smear positive samples that were tested by PCR were PCR-positive, and PCR detected additional 35 infections that were RDT/smear negative. In a multivariate logistic regression analysis, pregnant women had 5.4-fold higher odds of infection as compared to non-pregnant women. Malaria-positive pregnant women, though asymptomatic, had statistically lower hemoglobin than those without malaria or pregnancy. Asymptomatic malaria was found to be evenly distributed across space and time, in contrast to symptomatic infections which tend to cluster.
  
  
  CONCLUSIONS
  Pregnancy is a risk factor for asymptomatic P. falciparum infection in the Chittagong Hill Districts of Bangladesh, and pregnancy and malaria interact to heighten the effect of each on hemoglobin. The even distribution of asymptomatic malaria, without temporal and spatial clustering, may have critical implications for malaria elimination strategies.
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Wasif A
authors.initials: WA
authors.lastname: Khan
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Sean R
authors.initials: SR
authors.lastname: Galagan
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Chai Shwai
authors.initials: CS
authors.lastname: Prue
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Jacob
authors.initials: J
authors.lastname: Khyang
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Sabeena
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Malathi
authors.initials: M
authors.lastname: Ram
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Mohammad Shafiul
authors.initials: MS
authors.lastname: Alam
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: M Zahirul
authors.initials: MZ
authors.lastname: Haq
authors.affiliation: Centre for Population, Urbanization and Climate Change, International Centre for Diarrhoeal Disease Research, Bangladesh, Dhaka, Bangladesh.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Akter
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Gregory
authors.initials: G
authors.lastname: Glass
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Douglas E
authors.initials: DE
authors.lastname: Norris
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: Timothy
authors.initials: T
authors.lastname: Shields
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Sack
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors.forename: David J
authors.initials: DJ
authors.lastname: Sullivan
authors.affiliation: Johns Hopkins Malaria Research Institute, Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America.
authors.forename: Myaing M
authors.initials: MM
authors.lastname: Nyunt
mesh_terms: D000293:Adolescent; D000328:Adult; D001459:Bangladesh / Q000453:epidemiology; D062665:Epidemiological Monitoring; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000097:blood / Q000453:epidemiology*; D008297:Male; D010963:Plasmodium falciparum; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000097:blood / Q000453:epidemiology*; D012307:Risk Factors