title: Evaluation of the usefulness of Treponema pallidum hemagglutination test in the diagnosis of syphilis in weak reactive Venereal Disease Research Laboratory sera.
abstract: OBJECTIVE
  Biological false positive (BFP) reactivity by the Venereal Disease Research Laboratory (VDRL) test used for diagnosis of syphilis is a cause for concern. The use of the VDRL as a screening procedure is challenged by some studies. The aim of this study is to determine the prevalence of BFP reactions in different subject groups and to assess the usefulness of Treponema pallidum hemagglutination (TPHA) test in low titre VDRL reactive sera.
  
  
  METHODS
  A total of 5785 sera from sexually transmitted diseases (STD) clinic attendees, antenatal clinic attendees, husbands of antenatal cases, peripheral health centres attendees (representing community population) and from patients referred from different OPDs/wards were screened for BFP reactions by the VDRL test. Sera reactive in the VDRL test were confirmed by the TPHA test.
  
  
  RESULTS
  Out of 80 qualitative VDRL reactive sera, 68 had <1:8 titre on quantitation and TPHA was positive in 59 samples, indicating BFP reactivity in 0.2% in all the subject groups. BFP was nil in the community population. The male-to-female ratio of BFP reactions was 2:1. VDRL and TPHA positivity was highest (76%) in the age group of 20-29 years. The seroprevalence of syphilis varied from 0.4% to 3.5% in different patient groups.
  
  
  CONCLUSIONS
  The results of this study highlight that the TPHA positivity was high (86.8%) in sera with VDRL titre less than 1:8. Therefore, for the diagnosis of syphilis, it is recommended that a confirmatory test such as TPHA should be performed on all sera with a reactive VDRL regardless of its titre.
authors.affiliation: Regional STD Teaching, Training and Research Centre, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi, India.
authors.forename: Manju
authors.initials: M
authors.lastname: Bala
authors.forename: Aman
authors.initials: A
authors.lastname: Toor
authors.forename: Meenakshi
authors.initials: M
authors.lastname: Malhotra
authors.forename: Monika
authors.initials: M
authors.lastname: Kakran
authors.forename: Sumathi
authors.initials: S
authors.lastname: Muralidhar
authors.forename: V
authors.initials: V
authors.lastname: Ramesh