title: Malaria risk factors in Butajira area, south-central Ethiopia: a multilevel analysis.
abstract: BACKGROUND
  The highlands of Ethiopia, situated between 1,500 and 2,500 m above sea level, experienced severe malaria epidemics. Despite the intensive control attempts, underway since 2005 and followed by an initial decline, the disease remained a major public health concern. The aim of this study was to identify malaria risk factors in highland-fringe south-central Ethiopia.
  
  
  METHODS
  This study was conducted in six rural kebeles of Butajira area located 130 km south of Addis Ababa, which are part of demographic surveillance site in Meskan and Mareko Districts, Ethiopia. Using a multistage sampling technique 750 households was sampled to obtain the 3,398 people, the estimated sample size for this study. Six repeated cross-sectional surveys were conducted from October 2008 to June 2010. Multilevel, mixed-effects logistic regression models fitted to Plasmodium infection status (positive or negative) and six variables. Both fixed- and random-effects differences in malaria infection were estimated using median odds ratio and interval odds ratio 80%. The odds ratios and 95% confidence intervals were used to estimate the strength of association.
  
  
  RESULTS
  Overall, 19,207 individuals were sampled in six surveys (median and inter-quartile range value three). Six of the five variables had about two-fold to eight-fold increase in prevalence of malaria. Furthermore, among these variables, October-November survey seasons of both during 2008 and 2009 were strongly associated with increased prevalence of malaria infection. Children aged below five years (adjusted OR= 3.62) and children aged five to nine years (adj. OR= 3.39), low altitude (adj. OR= 5.22), mid-level altitude (adj. OR= 3.80), houses with holes (adj. OR= 1.59), survey seasons such as October-November 2008 (adj. OR= 7.84), January-February 2009 (adj. OR= 2.33), June-July 2009 (adj. OR=3.83), October-November 2009 (adj. OR= 7.71), and January-February 2010 (adj. OR= 3.05) were associated with increased malaria infection.The estimates of cluster variances revealed differences in malaria infection. The village-level intercept variance for the individual-level predictor (0.71 [95% CI: 0.28-1.82]; SE=0.34) and final (0.034, [95% CI: 0.002-0.615]; SE=0.05) were lower than that of empty (0.80, [95% CI: 0.32-2.01]; SE=0.21).
  
  
  CONCLUSIONS
  Malaria control efforts in highland fringes must prioritize children below ten years in designing transmission reduction of malaria elimination strategy.
authors.affiliation: Ethiopian Health and Nutrition Research Institute, P, O, Box 1242/5654, Addis Ababa, Ethiopia. woyessaa@yahoo.com
authors.forename: Adugna
authors.initials: A
authors.lastname: Woyessa
authors.forename: Wakgari
authors.initials: W
authors.lastname: Deressa
authors.forename: Ahmed
authors.initials: A
authors.lastname: Ali
authors.forename: Bernt
authors.initials: B
authors.lastname: Lindtjørn
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005002:Ethiopia / Q000453:epidemiology; D006801:Humans; D007223:Infant; D008288:Malaria / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D055361:Multilevel Analysis; D012307:Risk Factors; D012424:Rural Population; D012621:Seasons; D055815:Young Adult
references.citation: BMC Public Health. 2009 Oct 01;9:369
references.pmid: 19796380
references.citation: Acta Trop. 2003 Aug;87(3):331-40
references.pmid: 12875926
references.citation: Malar J. 2010 Jan 04;9:2
references.pmid: 20044942
references.citation: Int J Epidemiol. 2004 Dec;33(6):1337-44
references.pmid: 15242990
references.citation: Demography. 2001 Feb;38(1):115-32
references.pmid: 11227840
references.citation: Trans R Soc Trop Med Hyg. 2010 Feb;104(2):143-7
references.pmid: 19732924
references.citation: Malar J. 2011 Feb 03;10:25
references.pmid: 21288368
references.citation: Parasit Vectors. 2011 Dec 23;4:241
references.pmid: 22196078
references.citation: Malar J. 2009 Feb 13;8:27
references.pmid: 19216781
references.citation: J Epidemiol Community Health. 2006 Apr;60(4):290-7
references.pmid: 16537344
references.citation: Malar J. 2011 Apr 20;10:98
references.pmid: 21507217
references.citation: BMC Public Health. 2014 Jan 31;14:99
references.pmid: 24479770
references.citation: J Med Entomol. 2003 Sep;40(5):706-17
references.pmid: 14596287
references.citation: Am J Trop Med Hyg. 1991 Jul;45(1):77-85
references.pmid: 1867350
references.citation: Trans R Soc Trop Med Hyg. 2000 Jan-Feb;94(1):17-21
references.pmid: 10748890
references.citation: Trans R Soc Trop Med Hyg. 1995 Mar-Apr;89(2):146-50
references.pmid: 7778137
references.citation: Malar J. 2009 Jan 14;8:14
references.pmid: 19144183
references.citation: Trans R Soc Trop Med Hyg. 2007 Sep;101(9):939-47
references.pmid: 17602716
references.citation: Malar J. 2012 Mar 23;11:84
references.pmid: 22443307
references.citation: Malar J. 2011 Jun 24;10:173
references.pmid: 21699741
references.citation: Am J Trop Med Hyg. 2005 Jun;72(6):682-7
references.pmid: 15964950
references.citation: Malar J. 2009 Oct 12;8 Suppl 1:S8
references.pmid: 19818175
references.citation: Malar J. 2006 Nov 10;5:107
references.pmid: 17096835
references.citation: Trop Med Int Health. 2004 Jul;9(7):757-66
references.pmid: 15228485
references.citation: East Afr Med J. 2005 Apr;82(4):186-92
references.pmid: 16122086
references.citation: BMC Public Health. 2008 Sep 21;8:321
references.pmid: 18803880
references.citation: BMJ. 1999 Sep 11;319(7211):663-6
references.pmid: 10480820
references.citation: J Infect Dis. 2005 May 15;191(10):1589-98
references.pmid: 15838785
references.citation: Am J Trop Med Hyg. 2009 Jan;80(1):103-11
references.pmid: 19141847
references.citation: Trans R Soc Trop Med Hyg. 2009 Dec;103(12):1211-20
references.pmid: 19144366
references.citation: Am J Trop Med Hyg. 2009 Dec;81(6):944-9
references.pmid: 19996421