title: Prevalence and risk factors of Lassa seropositivity in inhabitants of the forest region of Guinea: a cross-sectional study.
abstract: BACKGROUND
  Lassa fever is a viral hemorrhagic fever endemic in West Africa. The reservoir host of the virus is a multimammate rat, Mastomys natalensis. Prevalence estimates of Lassa virus antibodies in humans vary greatly between studies, and the main modes of transmission of the virus from rodents to humans remain unclear. We aimed to (i) estimate the prevalence of Lassa virus-specific IgG antibodies (LV IgG) in the human population of a rural area of Guinea, and (ii) identify risk factors for positive LV IgG.
  
  
  RESULTS
  A population-based cross-sectional study design was used. In April 2000, all individuals one year of age and older living in three prefectures located in the tropical secondary forest area of Guinea (Gueckedou, Lola and Yomou) were sampled using two-stage cluster sampling. For each individual identified by the sampling procedure and who agreed to participate, a standardized questionnaire was completed to collect data on personal exposure to potential risk factors for Lassa fever (mainly contact with rodents), and a blood sample was tested for LV IgG. A multiple logistic regression model was used to determine risk factors for positive LV IgG. A total of 1424 subjects were interviewed and 977 sera were tested. Prevalence of positive LV Ig was of 12.9% [10.8%-15.0%] and 10.0% [8.1%-11.9%] in rural and urban areas, respectively. Two risk factors of positive LV IgG were identified: to have, in the past twelve months, undergone an injection (odds ratio [OR] = 1.8 [1.1-3.1]), or lived with someone displaying a haemorrhage (OR = 1.7 [1.1-2.9]). No factors related to contacts with rats and/or mice remained statistically significant in the multivariate analysis.
  
  
  CONCLUSIONS
  Our study underlines the potential importance of person-to-person transmission of Lassa fever, via close contact in the same household or nosocomial exposure.
authors.affiliation: Epicentre, Paris, France. solen.kerneis@cch.aphp.com
authors.forename: Solen
authors.initials: S
authors.lastname: Kernéis
authors.forename: Lamine
authors.initials: L
authors.lastname: Koivogui
authors.forename: N'Faly
authors.initials: N
authors.lastname: Magassouba
authors.forename: Kekoura
authors.initials: K
authors.lastname: Koulemou
authors.forename: Rosamund
authors.initials: R
authors.lastname: Lewis
authors.forename: Aristide
authors.initials: A
authors.lastname: Aplogan
authors.forename: Rebecca F
authors.initials: RF
authors.lastname: Grais
authors.forename: Philippe J
authors.initials: PJ
authors.lastname: Guerin
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fichet-Calvet
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology*; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004197:Disease Reservoirs / Q000821:virology; D005260:Female; D016701:Guinea / Q000453:epidemiology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007835:Lassa Fever / Q000097:blood / Q000453:epidemiology* / Q000276:immunology* / Q000635:transmission; D007836:Lassa virus / Q000276:immunology*; D008297:Male; D051379:Mice; D008875:Middle Aged; D010375:Pedigree; D015995:Prevalence; D051381:Rats; D012307:Risk Factors; D012377:Rodentia / Q000821:virology; D012424:Rural Population; D014504:Urban Health; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G