title: Characterizing viral subtypes to assess patterns of HIV transmission.
abstract: We characterized HIV-1 subtypes among 204 persons newly diagnosed with HIV in Ontario from 2003 to 2005 using samples from the Canadian HIV Strain and Drug Resistance Surveillance Program. We examined HIV-1 subtype by demographic characteristics and exposure category, and determined independent predictors of infection with a non-B HIV subtype using multivariate logistic regression. The distribution of HIV subtypes was: B 77.0%, C 10.3%, AG 4.9%, A 2.5%, AE 2.5% and others 3.0%. Overall, 23.0% were non-B, greater in women than in men (62.8% versus 12.4%, P < 0.0001) and persons under 35 years (31.1% versus 18.5% in those ≥35, P = 0.04). Non-B subtype was predominant (78.9%) among persons from HIV-endemic regions and considerable (28.6%) among other persons infected heterosexually. In multivariate modelling adjusted for gender, non-B subtype was significantly associated with birth in an HIV-endemic region (adjusted odds ratio [aOR] 59.2, P < 0.0001) and heterosexual exposure (aOR 6.3, P = 0.02). Additionally, compared with men who had sex with men, non-B subtype was greater among heterosexual women (aOR 17.8, P < 0.001) and women who injected drugs (injection drug use, aOR 13.4, P = 0.01). We found a non-negligible proportion of non-B subtypes among women infected heterosexually not from HIV-endemic countries, providing interesting insights into HIV transmission patterns.
authors.affiliation: Surveillance and Epidemiology Division, Public Health Agency of Canada, Ottawa, Canada.
authors.forename: C
authors.initials: C
authors.lastname: Rank
authors.forename: J G
authors.initials: JG
authors.lastname: Njihia
authors.forename: R S
authors.initials: RS
authors.lastname: Remis
authors.forename: L
authors.initials: L
authors.lastname: Shah
authors.forename: C
authors.initials: C
authors.lastname: Swantee
authors.forename: J I
authors.initials: JI
authors.lastname: Brooks
authors.forename: G C
authors.initials: GC
authors.lastname: Jayaraman
authors.forename: C P
authors.initials: CP
authors.lastname: Archibald
mesh_terms: D000328:Adult; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D015658:HIV Infections / Q000453:epidemiology / Q000635:transmission* / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics; D006716:Homosexuality; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D012111:Residence Characteristics; D012307:Risk Factors