1. P. Jha is at the Economics Advisory Service, World Health Organization, Geneva, Switzerland.
2. N. J. D. Nagelkerke, B. Willbond, S. Moses, and F. A. Plummer are in the Departments of Medical Microbiology, Community Health Sciences and Medicine, University of Manitoba, Winnipeg, MB, Canada R3E 0W3.
3. N.J.D.N. is also in the Department of Public Health, University of Rotterdam, Rotterdam, and National Institute of Public Health and the Environment, Amsterdam, Netherlands.
4. E. N. Ngugi and F.A.P. are at the Department of Community Health, University of Nairobi, Nairobi, Kenya.
5. J. V. R. Prasada Rao is at the National AIDS Control Organization, Ministry of Health and Family Welfare, New Delhi, India.
6. F.A.P. is also at the National Microbiology Laboratory, Health Canada, Winnipeg, MB, Canada.