Case-control study of HIV seroconversion in health care workers after percutaneous exposure to HIV-infected blood: D. Cardo, MD, P. Srivastava, MS, C. Ciesielski, MD, R. Marcus, MPH, P. McKibben, D. Culver, PhD, B. Bolyard, RN, MPH,∗ D. Bell, MD. Needlestick Surveillance Group, Centers for Disease Control and Prevention, Atlanta, GA