title: Risk factors for late postnatal transmission of human immunodeficiency virus type 1 in sub-Saharan Africa.
abstract: BACKGROUND
  We conducted secondary data analyses of a clinical trial (HIVNET 024) to assess risk factors for late postnatal transmission (LPT) of human immunodeficiency virus type 1 (HIV-1) through breast-feeding.
  
  
  METHODS
  Data regarding live born, singleton infants of HIV-1-infected mothers were analyzed. The timing of HIV-1 transmission through 12 months after birth was defined as: in utero (positive HIV-1 RNA results at birth), perinatal/early postnatal (negative results at birth, positive at 4-6 week visit), or LPT (negative results through the 4-6 week visit, but positive assays thereafter through the 12-month visit). HIV-1-uninfected infants were those with negative HIV-1 enzyme immunoassay results at 12 months of age, or infants with negative HIV-1 RNA results throughout follow-up.
  
  
  RESULTS
  Of 2292 HIV-1-infected enrolled women, 2052 mother/infant pairs met inclusion criteria. Of 1979 infants with HIV-1 tests, 404 were HIV-1-infected, and 382 had known timing of infection (LPT represented 22% of transmissions). Further analyses of LPT included infants who were breast-feeding at the 4-6 week visit (with negative HIV-1 results at that visit) revealed 6.9% of 1317 infants acquired HIV-1 infection through LPT by 12 months of age. More advanced maternal HIV-1 disease at enrollment (lower CD4 counts, higher plasma viral loads) were the factors associated with LPT in adjusted analyses.
  
  
  CONCLUSIONS
  In this breast-feeding population, 6.9% of infants uninfected at 6 weeks of age acquired HIV-1 infection by 12 months. Making interventions to decrease the risk of LPT of HIV-1 available and continuing research regarding the mechanisms of LPT (so as to develop improved interventions to reduce such transmission) remain essential.
authors.affiliation: University of North Carolina Project, Kamuzu Central Hospital, Lilongwe, Malawi. charles.chasela@ucd.ie
authors.forename: Charles
authors.initials: C
authors.lastname: Chasela
authors.forename: Ying Qing
authors.initials: YQ
authors.lastname: Chen
authors.forename: Susan
authors.initials: S
authors.lastname: Fiscus
authors.forename: Irving
authors.initials: I
authors.lastname: Hoffman
authors.forename: Alicia
authors.initials: A
authors.lastname: Young
authors.forename: Megan
authors.initials: M
authors.lastname: Valentine
authors.forename: Lynda
authors.initials: L
authors.lastname: Emel
authors.forename: Taha E
authors.initials: TE
authors.lastname: Taha
authors.forename: Robert L
authors.initials: RL
authors.lastname: Goldenberg
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Read
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000914:Antibodies, Viral / Q000097:blood; D001942:Breast Feeding / Q000009:adverse effects*; D018791:CD4 Lymphocyte Count; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission*; D015497:HIV-1 / Q000302:isolation & purification*; D006801:Humans; D007231:Infant, Newborn; D018445:Infectious Disease Transmission, Vertical; D009035:Mothers; D012367:RNA, Viral / Q000097:blood; D012307:Risk Factors; D019562:Viral Load
chemical_list: D000914:Antibodies, Viral; D012367:RNA, Viral