1. Department of Epidemiology, Institute of Public Health Celje, Ipavceva 18, Sl 3000 Celje, Slovenia
2. Clinical Institute for Laboratory Diagnostics of the University School of Medicine Zagreb and Clinical Hospital Centre Zagreb, Croatia
3. Department of Dermatovenereology, University Medical Centre Ljubljana, Ljubljana, Slovenia
4. Department of Genito-Urinary Medicine, General Infirmary, Leeds LS