1. Blood Systems Research Institute, San Francisco, California
2. Dept. of Laboratory Medicine, University of California, San Francisco, San Francisco, California
3. Stanford Genome Technology Center, Stanford University, Stanford, California
4. Department of Enteric Diseases, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
5. CIWEC Clinic Travel Medicine Center, Katmandu, Nepal
6. Laboratory of Clinical Virology, WHO Regional Reference Laboratory on Poliomyelitis, Institut Pasteur, Tunis, Tunisia
7. WHO National Polio Laboratory, University of Maiduguri Teaching Hospital, Borno State, Nigeria
8. Molecular Epidemiology Unit, Public Health Laboratory Division, Minnesota Dept. of Health, St. Paul, Minnesota