title: Impact of long-lasting insecticidal nets on prevalence of subclinical malaria among children in the presence of pyrethroid resistance in Anopheles culicifacies in Central India.
abstract: BACKGROUND
  Subclinical (asymptomatic) cases of malaria could be a major barrier to the success of malaria elimination programs. This study has evaluated the impact of long-lasting insecticidal nets (LLINs) on the prevalence of subclinical malaria in the presence of pyrethroid resistance in the main malaria vector Anopheles culicifacies on malaria transmission among a cohort of children in villages of the Keshkal sub-district in Chhattisgarh state.
  
  
  METHODS
  A cohort of 6582 children ages less than 14 years was enrolled from 80 study clusters. Post monsoon survey was carried out at baseline before LLIN distribution, and 5862 children were followed up in the subsequent year. Study outcomes included assessment of subclinical malarial infections and use of LLINs among the study cohort in the presence of varied levels of pyrethroid resistance.
  
  
  RESULTS
  In the baseline survey, the proportion of subclinical malaria was 6·1%. LLIN use during the previous night was 94·8%. Overall, prevalence of subclinical malaria was significantly reduced to 1% (p<0·001) in the second survey. LLIN users were protected from malaria (OR: 0·25, 95% CI=0·12-0·52, p<0.001) and subclinical malaria (OR: 0·25, 95% CI=0·11-0·58, p=0·001) despite the presence of pyrethroid resistance in the study area.
  
  
  CONCLUSIONS
  In this low transmission area, sleeping under LLINs significantly reduced the burden of malaria among children. In the presence of pyrethroid resistant malaria vector, a high LLIN use of 94·5% was observed to have significantly brought down the proportion of subclinical malaria among the cohort children.
authors.affiliation: National Institute of Malaria Research (ICMR) IIR-WHO Project, Field Unit, Kondagaon, Chhattisgarh, India. Electronic address: mehul4frnds@gmail.com.
authors.forename: Mehul Kumar
authors.initials: MK
authors.lastname: Chourasia
authors.affiliation: National Institute of Malaria Research (ICMR), Sector-8, Dwarka, New Delhi 110077, India. Electronic address: kamarajur2000@yahoo.com.
authors.forename: Raghavendra
authors.initials: R
authors.lastname: Kamaraju
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK. Electronic address: immo.kleinschmidt@lshtm.ac.uk.
authors.forename: Immo
authors.initials: I
authors.lastname: Kleinschmidt
authors.affiliation: National Institute of Malaria Research (ICMR), Field Unit, Lalpur, Raipur Chhattisgarh, India. Electronic address: rmbhatt@rediffmail.com.
authors.forename: Rajendra M
authors.initials: RM
authors.lastname: Bhatt
authors.affiliation: National Institute of Malaria Research (ICMR) IIR-WHO Project, Field Unit, Kondagaon, Chhattisgarh, India. Electronic address: dipakswain@gmail.com.
authors.forename: Dipak Kumar
authors.initials: DK
authors.lastname: Swain
authors.affiliation: World Health Organization, Avenue Appia, 1211 Geneva-27, Switzerland. Electronic address: knoxt@who.int.
authors.forename: Tessa Bellamy
authors.initials: TB
authors.lastname: Knox
authors.affiliation: National Institute of Malaria Research (ICMR), Sector-8, Dwarka, New Delhi 110077, India. Electronic address: neenavalecha@gmail.com.
authors.forename: Neena
authors.initials: N
authors.lastname: Valecha
mesh_terms: D000818:Animals; D000852:Anopheles; D002648:Child; D005260:Female; D006801:Humans; D007194:India; D007223:Infant; D007305:Insecticide Resistance; D057148:Insecticide-Treated Bednets; D007306:Insecticides / Q000494:pharmacology*; D008288:Malaria / Q000453:epidemiology*; D008297:Male; D009032:Mosquito Control; D015995:Prevalence; D011722:Pyrethrins / Q000494:pharmacology*
chemical_list: D007306:Insecticides; D011722:Pyrethrins
keywords: India; LLIN; Malaria; Pyrethroid resistance; Subclinical malaria