title: A case study of risk factors for lymphatic filariasis in the Republic of Congo.
abstract: BACKGROUND
  Little is known regarding risk factors for lymphatic filariasis (LF) in Central Africa. We studied the epidemiology of LF in an endemic village in the Republic of Congo.
  
  
  METHODS
  Dependent variables were Wuchereria bancrofti antigenemia (ICT card test) and microfilaremia (night blood smears). The following factors were investigated: sex, age, bed net, latrines, source of water, uptake of anthelmintic drugs, hunting/fishing activities, and occasionally sleeping in the bush. Mixed multivariate logistic regression models were used.
  
  
  RESULTS
  134 of 774 subjects aged ≥ 5 years (17.3%) had W. bancrofti antigenemia and 41 (5.3%) had microfilaremia (mf). Infection rates increased with age up to roughly 20 years and remained stable thereafter. Multivariate analysis of antigenemia demonstrated an increased risk for males (OR = 2.0 [1.3-3.0]) and for people who hunt or fish (OR = 1.5 [1.0-2.4]) and a protective effect of latrines (OR = 0.5 [0.4-0.8]). Among males, those hunting or fishing at night had an increased risk for antigenemia (OR = 1.9 [1.1-3.5]), and use of latrines was protective (OR = 0.5 [0.3-0.9]). For females, bed nets were protective (OR = 0.4 [0.1-0.9]), and there was a strong household effect (intraclass correlation coefficient [ICC]: 0.24). When mf was used as the dependent variable, males had a higher risk for infection (OR = 5.4 [2.1-13.4]), latrines had a protective effect (OR = 0.4 [0.1-0.9]) and there was a marked household effect (ICC = 0.49).
  
  
  CONCLUSIONS
  Age, sex, and occupation-dependent exposure to mosquitoes were important risk factors for infection with W. bancrofti in this study. It is likely that men often acquire infection in high transmission areas outside of the village, while children and women are infected in areas with lower transmission inside or near the village. Additional studies are needed to determine whether these findings apply to other areas in Central Africa.
authors.affiliation: UMI 233, Institut de Recherche pour le Développement (IRD) and University of Montpellier 1, 911 avenue Agropolis, P,O, Box 64501, 34394 Montpellier, Cedex 5, France. cedric.chesnais@ird.fr.
authors.forename: Cédric B
authors.initials: CB
authors.lastname: Chesnais
authors.forename: François
authors.initials: F
authors.lastname: Missamou
authors.forename: Sébastien D
authors.initials: SD
authors.lastname: Pion
authors.forename: Jean
authors.initials: J
authors.lastname: Bopda
authors.forename: Frédéric
authors.initials: F
authors.lastname: Louya
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Majewski
authors.forename: Peter U
authors.initials: PU
authors.lastname: Fischer
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Weil
authors.forename: Michel
authors.initials: M
authors.lastname: Boussinesq
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000871:Anthelmintics / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003223:Congo / Q000453:epidemiology; D004605:Elephantiasis, Filarial / Q000453:epidemiology*; D005260:Female; D006801:Humans; D057148:Insecticide-Treated Bednets; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D012498:Sanitary Engineering; D014881:Water Supply; D055815:Young Adult
chemical_list: D000871:Anthelmintics