title: The when and how of male circumcision and the risk of HIV: a retrospective cross-sectional analysis of two HIV surveys from Guinea-Bissau.
abstract: BACKGROUND
  Male circumcision (MC) reduces the risk of HIV, and this risk reduction may be modified by socio-cultural factors such as the timing and method (medical and traditional) of circumcision. Understanding regional variations in circumcision practices and their relationship to HIV is crucial and can increase insight into the HIV epidemic in Africa.
  
  
  METHODS
  We used data from two retrospective HIV surveys conducted in Guinea-Bissau from 1993 to 1996 (1996 cohort) and from 2004 to 2007 (2006 cohort). Multivariate logistical models were used to investigate the relationships between HIV risk and circumcision status, timing, method of circumcision, and socio-demographic factors.
  
  
  RESULTS
  MC was protective against HIV infection in both cohorts, with adjusted odds ratios (AORs) of 0.28 (95% CI 0.12-0.66) and 0.30 (95% CI 0.09-0.93), respectively. We observed that post-pubertal (≥ 13 years) circumcision provided the highest level of HIV risk reduction in both cohorts compared to non-circumcised. However, the difference between pre-pubertal (≤ 12 years) and post-pubertal (≥ 13 years) circumcision was not significant in the multivariate analysis. Seventy-six percent (678/888) of circumcised males in the 2006 cohort were circumcised traditionally, and 7.7% of those males were HIV-infected compared to 1.9% of males circumcised medically, with AOR of 2.7 (95% CI 0.91-8.12).
  
  
  CONCLUSIONS
  MC is highly prevalent in Guinea-Bissau, but ethnic variations in method and timing may affect its protection against HIV. Our findings suggest that sexual risk behaviour and traditional circumcision may increases HIV risk. The relationship between circumcision age, sexual behaviour and HIV status remains unclear and warrants further research.
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau; Department of Infectious Diseases, Odense University Hospital, DK-5000 Odense, Denmark; Center for Global Health, Institute of Clinical Research, University of Southern Denmark, DK-5000 Odense, Denmark.
authors.forename: Dlama Nggida
authors.initials: DN
authors.lastname: Rasmussen
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau; Department of Infectious Diseases, Aarhus University Hospital, DK-8200 Aarhus, Denmark; Center for Global Health, Department of Public Health, Aarhus University, DK-8000 Aarhus, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Wejse
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau; Department of Infectious Diseases, Odense University Hospital, DK-5000 Odense, Denmark.
authors.forename: Olav
authors.initials: O
authors.lastname: Larsen
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau.
authors.forename: Zacarias
authors.initials: Z
authors.lastname: Da Silva
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau; Statens Serums Institute, DK-2300 Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
authors.affiliation: Bandim Health Project, Indepth Network, Apartado 861, 1004 Bissau Codex, Bissau, Guinea-Bissau; Department of Infectious Diseases, Odense University Hospital, DK-5000 Odense, Denmark; Center for Global Health, Institute of Clinical Research, University of Southern Denmark, DK-5000 Odense, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Sodemann
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002944:Circumcision, Male / Q000706:statistics & numerical data*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D006169:Guinea-Bissau; D015658:HIV Infections / Q000517:prevention & control*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D012189:Retrospective Studies; D040242:Risk Reduction Behavior; D012309:Risk-Taking; D012725:Sexual Behavior; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Africa; HIV prevention; HIV/AIDS; circumcision; risk behaviour