title: [Characteristics of HIV infections among over 50-year-olds population in China].
abstract: OBJECTIVE
  To analyze the characteristics on demographical, spatial distribution and transmission mode of HIV infections among 50-year-old population.
  
  
  METHODS
  Related information on demography, spatial distribution, high risk behavioral and history of HIV infections among 50-year-old population were collected and analyzed. Possible time of infection based on their first CD4 testing results right after the HIV diagnoses, was estimated.
  
  
  RESULTS
  Since 2008, the number of new HIV/AIDS cases among the over-50-year-olds was reported increasing annually. The number of aged 50 and above in 2014 was 4.2 times than the number in 2008. 50-year-old or older population were infected mainly through heterosexual behavior (88.0%). Among these cases, 83.9% self-reported as having histories on extramarital sex intercourse and the number was increasing yearly. Among male cases who admitted as having heterosexual experience, 95.1% of them reported as having histories of extramarital sex intercourse while 53.4% of the female cases reported as having the same experiences. 46.6% of spouses of the females or with fixed partners were HIV positive. Through estimating the time of infection and the time interval between infection and diagnosis, we found that the proportion was 15.5%, from infection to diagnosis as 3 years among the 50 and older age groups, but the proportion of 8 years from infection to diagnosis was 43.6%. We estimated that 66.5% of the new HIV cases who were at age 50 and over, were infected when they were at that age span. The average time from infection and being tested was (6.8 ± 2.7) years.
  
  
  CONCLUSIONS
  The increasing number of being diagnosed on HIV among the 50-year-olds population might be related to both high risk exposure and belated diagnoses among this population, calling for the necessity of deriving the sources of HIV infection and tailoring the HIV prevention strategies in this population.
authors.affiliation: Division of Epidemiology, National Center for AIDS/STD Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China.
authors.forename: L Y
authors.initials: LY
authors.lastname: Wang
authors.forename: Q Q
authors.initials: QQ
authors.lastname: Qin
authors.forename: L
authors.initials: L
authors.lastname: Ge
authors.forename: Z W
authors.initials: ZW
authors.lastname: Ding
authors.forename: C
authors.initials: C
authors.lastname: Cai
authors.forename: W
authors.initials: W
authors.lastname: Guo
authors.forename: Y
authors.initials: Y
authors.lastname: Cui
mesh_terms: D002681:China / Q000453:epidemiology; D005260:Female; D015658:HIV Infections / Q000453:epidemiology*; D020010:Heterosexuality / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012309:Risk-Taking; D012747:Sexual Partners / Q000523:psychology