title: Decreasing Proportion of Recent Infections among Newly Diagnosed HIV-1 Cases in Switzerland, 2008 to 2013 Based on Line-Immunoassay-Based Algorithms.
abstract: BACKGROUND
  HIV surveillance requires monitoring of new HIV diagnoses and differentiation of incident and older infections. In 2008, Switzerland implemented a system for monitoring incident HIV infections based on the results of a line immunoassay (Inno-Lia) mandatorily conducted for HIV confirmation and type differentiation (HIV-1, HIV-2) of all newly diagnosed patients. Based on this system, we assessed the proportion of incident HIV infection among newly diagnosed cases in Switzerland during 2008-2013.
  
  
  RESULTS
  Inno-Lia antibody reaction patterns recorded in anonymous HIV notifications to the federal health authority were classified by 10 published algorithms into incident (up to 12 months) or older infections. Utilizing these data, annual incident infection estimates were obtained in two ways, (i) based on the diagnostic performance of the algorithms and utilizing the relationship 'incident = true incident + false incident', (ii) based on the window-periods of the algorithms and utilizing the relationship 'Prevalence = Incidence x Duration'. From 2008-2013, 3'851 HIV notifications were received. Adult HIV-1 infections amounted to 3'809 cases, and 3'636 of them (95.5%) contained Inno-Lia data. Incident infection totals calculated were similar for the performance- and window-based methods, amounting on average to 1'755 (95% confidence interval, 1588-1923) and 1'790 cases (95% CI, 1679-1900), respectively. More than half of these were among men who had sex with men. Both methods showed a continuous decline of annual incident infections 2008-2013, totaling -59.5% and -50.2%, respectively. The decline of incident infections continued even in 2012, when a 15% increase in HIV notifications had been observed. This increase was entirely due to older infections. Overall declines 2008-2013 were of similar extent among the major transmission groups.
  
  
  CONCLUSIONS
  Inno-Lia based incident HIV-1 infection surveillance proved useful and reliable. It represents a free, additional public health benefit of the use of this relatively costly test for HIV confirmation and type differentiation.
authors.affiliation: University of Zurich, Institute of Medical Virology, Swiss National Center for Retroviruses, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
authors.forename: Jörg
authors.initials: J
authors.lastname: Schüpbach
authors.affiliation: Blood Transfusion Service, Swiss Red Cross Berne, Berne, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Niederhauser
authors.affiliation: Geneva University Hospitals, Laboratory of Virology, Genève, 14, Switzerland.
authors.forename: Sabine
authors.initials: S
authors.lastname: Yerly
authors.affiliation: University Hospital, Clinic for Immunology, Zurich, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Regenass
authors.affiliation: University of Berne, Institute of Infectious Diseases, Berne, Switzerland.
authors.forename: Meri
authors.initials: M
authors.lastname: Gorgievski
authors.affiliation: University Hospital, Service of Immunology and Allergy, University Hospital Center, Lausanne, Switzerland.
authors.forename: Vincent
authors.initials: V
authors.lastname: Aubert
authors.affiliation: Institut Dr. Viollier AG, Basel, Switzerland.
authors.forename: Diana
authors.initials: D
authors.lastname: Ciardo
authors.affiliation: University of Basel, Institute for Medical Microbiology, Basel, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Klimkait
authors.affiliation: Zentrum für Labormedizin St. Gallen, St. Gallen, Switzerland.
authors.forename: Günter
authors.initials: G
authors.lastname: Dollenmaier
authors.affiliation: Clinique de la Source, Laboratoire, Lausanne, Switzerland.
authors.forename: Corinne
authors.initials: C
authors.lastname: Andreutti
authors.affiliation: Ente ospedaliero cantonale, Servizio di microbiologia, Bellinzona, Switzerland.
authors.forename: Gladys
authors.initials: G
authors.lastname: Martinetti
authors.affiliation: Labor Synlab Luzern, Lucerne, Switzerland.
authors.forename: Marcel
authors.initials: M
authors.lastname: Brandenberger
authors.affiliation: Swiss Federal Office of Public Health, CH-3003, Berne, Switzerland.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Gebhardt
mesh_terms: D000328:Adult; D000465:Algorithms; D003430:Cross-Sectional Studies; D062665:Epidemiological Monitoring; D005260:Female; D015483:HIV Antibodies / Q000097:blood*; D015658:HIV Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1 / Q000276:immunology; D015498:HIV-2 / Q000276:immunology; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D013557:Switzerland / Q000453:epidemiology
chemical_list: D015483:HIV Antibodies