1. Rajendra Memorial Research Institute of Medical Sciences, Agam Kuan, Patna 800 007, India
2. National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme-XM, Beliaghata, Kolkata 700 010, India
3. National Center for Infectious Diseases, Centers for Disease Control and Prevention, Building 22, Mail Stop F-12, 4770 Buford Highway, Atlanta, Georgia 30334