title: The role of migration and domestic transmission in the spread of HIV-1 non-B subtypes in Switzerland.
abstract: BACKGROUND
  By analyzing human immunodeficiency virus type 1 (HIV-1) pol sequences from the Swiss HIV Cohort Study (SHCS), we explored whether the prevalence of non-B subtypes reflects domestic transmission or migration patterns.
  
  
  METHODS
  Swiss non-B sequences and sequences collected abroad were pooled to construct maximum likelihood trees, which were analyzed for Swiss-specific subepidemics, (subtrees including ≥80% Swiss sequences, bootstrap >70%; macroscale analysis) or evidence for domestic transmission (sequence pairs with genetic distance <1.5%, bootstrap ≥98%; microscale analysis).
  
  
  RESULTS
  Of 8287 SHCS participants, 1732 (21%) were infected with non-B subtypes, of which A (n = 328), C (n = 272), CRF01_AE (n = 258), and CRF02_AG (n = 285) were studied further. The macroscale analysis revealed that 21% (A), 16% (C), 24% (CRF01_AE), and 28% (CRF02_AG) belonged to Swiss-specific subepidemics. The microscale analysis identified 26 possible transmission pairs: 3 (12%) including only homosexual Swiss men of white ethnicity; 3 (12%) including homosexual white men from Switzerland and partners from foreign countries; and 10 (38%) involving heterosexual white Swiss men and females of different nationality and predominantly nonwhite ethnicity.
  
  
  CONCLUSIONS
  Of all non-B infections diagnosed in Switzerland, <25% could be prevented by domestic interventions. Awareness should be raised among immigrants and Swiss individuals with partners from high prevalence countries to contain the spread of non-B subtypes.
authors: Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, Switzerland. vowv@usz.uzh.ch
authors: Viktor
authors: V
authors: von Wyl
authors: Roger D
authors: RD
authors: Kouyos
authors: Sabine
authors: S
authors: Yerly
authors: Jürg
authors: J
authors: Böni
authors: Cyril
authors: C
authors: Shah
authors: Philippe
authors: P
authors: Bürgisser
authors: Thomas
authors: T
authors: Klimkait
authors: Rainer
authors: R
authors: Weber
authors: Bernard
authors: B
authors: Hirschel
authors: Matthias
authors: M
authors: Cavassini
authors: Cornelia
authors: C
authors: Staehelin
authors: Manuel
authors: M
authors: Battegay
authors: Pietro L
authors: PL
authors: Vernazza
authors: Enos
authors: E
authors: Bernasconi
authors: Bruno
authors: B
authors: Ledergerber
authors: Sebastian
authors: S
authors: Bonhoeffer
authors: Huldrych F
authors: HF
authors: Günthard
mesh_terms: D044466:Asian People / Q000706:statistics & numerical data; D044383:Black People / Q000706:statistics & numerical data; D016000:Cluster Analysis; D004641:Emigration and Immigration; D005260:Female; D015684:Gene Products, pol / Q000378:metabolism; D015658:HIV Infections / Q000208:ethnology* / Q000235:genetics / Q000635:transmission*; D015497:HIV-1 / Q000235:genetics* / Q000378:metabolism; D020010:Heterosexuality / Q000706:statistics & numerical data; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D008969:Molecular Sequence Data; D015995:Prevalence; D013557:Switzerland / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data
chemical_list: D015684:Gene Products, pol