title: Effects of community-level bed net coverage on malaria morbidity in Lilongwe, Malawi.
abstract: The protective effect of insecticide-treated bed nets against individual-level malaria transmission is well known, however community-level effects are less understood. Protective effects from community-level bed net use against malaria transmission have been observed in clinical trials, however, the relationship is less clear outside of a controlled research setting. The objective of this research was to investigate the effect of community-level bed net use against malaria transmission outside of a bed net clinical trial setting in Lilongwe, Malawi following national efforts to scale-up ownership of long-lasting, insecticide-treated bed nets.
  
  
  
  An annual, cross-sectional, household-randomized, malaria transmission intensity survey was conducted in Lilongwe, Malawi (2011-2013). Health, demographic, and geographic-location data were collected. Participant blood samples were tested for Plasmodium falciparum presence. The percentage of people sleeping under a bed net within 400-m and 1-km radii of all participants was measured. Mixed effects logistic regression models were used to measure the relationship between malaria prevalence and surrounding bed net coverage. Each year, 800 people were enrolled (400 <5 years; 200 5-19 years; 200 ≥20 years; total n = 2400).
  
  
  
  From 2011 to 2013, malaria prevalence declined from 12.9 to 5.6%, while bed net use increased from 53.8 to 78.6%. For every 1% increase in community bed net coverage, malaria prevalence decreased among children under 5 years old [adjusted odds ratio: 0.98 (0.96, 1.00)]. Similar effects were observed in participants 5-19 years [unadjusted odds ratio: 0.98 (0.97, 1.00)]; the effect was attenuated after adjusting for individual-level bed net use. Community coverage was not associated with malaria prevalence among adults ≥20 years. Supplemental analyses identified more pronounced indirect protective effects from community-level bed net use against malaria transmission among children under 5 years who were sleeping under a bed net [adjusted odds ratio: 0.97 (0.94, 0.99)], compared to children who were not sleeping under a bed net [adjusted odds ratio: 0.99 (0.97, 1.01)].
  
  
  
  Malawi's efforts to scale up ownership of long-lasting, insecticide-treated bed nets are effective in increasing reported use. Increased community-level bed net coverage appears to provide additional protection against malaria transmission beyond individual use in a real-world context.
authors.affiliation: Carolina Population Center, University of North Carolina, 308 W Rosemary, CB 8120, Chapel Hill, NC, 27599, USA. escamill@email.unc.edu.
authors.forename: Veronica
authors.initials: V
authors.lastname: Escamilla
authors.affiliation: Division of Infectious Diseases, University of North Carolina, Chapel Hill, NC, 27599, USA.
authors.forename: Alisa
authors.initials: A
authors.lastname: Alker
authors.affiliation: UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Leonard
authors.initials: L
authors.lastname: Dandalo
authors.affiliation: Division of Infectious Diseases, University of North Carolina, Chapel Hill, NC, 27599, USA.|Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA.|Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC, 27599, USA.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Juliano
authors.affiliation: Division of Infectious Diseases, University of North Carolina, Chapel Hill, NC, 27599, USA.|Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA.
authors.forename: William C
authors.initials: WC
authors.lastname: Miller
authors.affiliation: UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Portia
authors.initials: P
authors.lastname: Kamthuza
authors.affiliation: UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Tapiwa
authors.initials: T
authors.lastname: Tembo
authors.affiliation: UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Gerald
authors.initials: G
authors.lastname: Tegha
authors.affiliation: UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Francis
authors.initials: F
authors.lastname: Martinson
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, 27599, USA.|Department of Geography, University of North Carolina, Chapel Hill, NC, 27599, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Emch
authors.affiliation: Division of Infectious Diseases, University of North Carolina, Chapel Hill, NC, 27599, USA.|UNC Project-Malawi, Lilongwe, Malawi.
authors.forename: Irving F
authors.initials: IF
authors.lastname: Hoffman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D018562:Disease Transmission, Infectious / Q000517:prevention & control*; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D057148:Insecticide-Treated Bednets / Q000706:statistics & numerical data*; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000517:prevention & control*; D008295:Malawi / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009032:Mosquito Control / Q000379:methods*; D010963:Plasmodium falciparum; D015995:Prevalence; D011897:Random Allocation; D055815:Young Adult