1 Biostatistics Section, and Division of Bacteriology, National Institute for Biological Standards and Control, South Mimms, Potters Bar, Sexually Transmitted Bacteria Reference Laboratory, Health Protection Agency, Centre for Infections, Colindale, United Kingdom; Laboratory Reference and Research Branch, Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; Labor Dr. Krone and Partner, Bad Salzuflen, Germany; Sexually Transmitted Infections Reference Centre, National Institute for Communicable Diseases (NHLS), Johannesburg, South Africa; Diagnostic Laboratory for Infectious Diseases & Perinatal Screening Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands; Dept. of Clinical Biochemistry, Statens Serum Institut, Copenhagen, Denmark; SEALS Area Serology Laboratory, Prince of Wales Hospital, Randwick, New South Wales, Australia; and HUSLAB, Unit of Immunology, Clinical Microbiology, Helsinki University Hospital, Helsinki, Finland.