Viral: 17. cytomegalovirus 18. Epstein Barr virus 19. hepatitis A 20. hepatitis B 21. hepatitis C 22. hepaptitis D 23. herpes simplex virus (HSV-1 and HSV-2) 24. human immunodeficiency virus (HIV) 25. human papillomavirus (HPV) 26. human T-cell lymphotropic virus (HTLV-1) 27. molluscum contagiosum