title: Health centre surveys as a potential tool for monitoring malaria epidemiology by area and over time.
abstract: BACKGROUND
  Presently, many malaria control programmes use health facility data to evaluate the impact of their interventions. Facility-based malaria data, although useful, have problems with completeness, validity and representativeness and reliance on routinely collected health facility data might undermine demonstration of the magnitude of the impact of the recent scaleups of malaria interventions. To determine whether carefully conducted health centre surveys can be reliable means of monitoring area specific malaria epidemiology, we have compared malaria specific indices obtained from surveys in health centres with indices obtained from cross-sectional surveys conducted in their catchment communities.
  
  
  METHODS
  A series of age stratified, seasonal, cross-sectional surveys were conducted during the peak malaria transmission season in 2008 and during the following dry season in 2009 in six ecologically diverse areas in The Gambia. Participants were patients who attended the health centres plus a representative sample from the catchment villages of these health facilities. Parasitaemia, anaemia, attributable proportion of fever and anti-MSP1-(19) antibody seroprevalence were compared in the health facility attendees and community participants.
  
  
  RESULTS
  A total of 16,230 subjects completed the study; approximately half participated in the health centre surveys and half in the wet season surveys. Data from both the health centre and community surveys showed that malaria endemicity in The Gambia is now low, heterogeneous and seasonal. In the wet season, parasitaemia, seroprevalence and fever prevalence were higher in subjects seen in the health centres than in the community surveys. Age patterns of parasitaemia, attributable proportions of fever and seroprevalence rates were similar in subjects who participated in the community and health centre surveys.
  
  
  CONCLUSIONS
  Health centre surveys have potential as a surveillance tool for evaluating area specific malaria control activities and for monitoring changes in local malaria epidemiology over time.
authors.affiliation: Medical Research Council Laboratories, Banjul, The Gambia. aroduro@yahoo.com
authors.forename: Abraham R
authors.initials: AR
authors.lastname: Oduro
authors.forename: Kalifa A
authors.initials: KA
authors.lastname: Bojang
authors.forename: David J
authors.initials: DJ
authors.lastname: Conway
authors.forename: Tumani
authors.initials: T
authors.lastname: Corrah
authors.forename: Brian M
authors.initials: BM
authors.lastname: Greenwood
authors.forename: David
authors.initials: D
authors.lastname: Schellenberg
mesh_terms: D000367:Age Factors; D000554:Ambulatory Care Facilities / Q000458:organization & administration*; D003430:Cross-Sectional Studies; D005260:Female; D005714:Gambia / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D008288:Malaria / Q000453:epidemiology*; D008297:Male
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