[1] Hamilton Regional Laboratory Program, Mc Master University, Hamilton, Ont.
[2] Dept. of Pathol. and Molec. Medicine, Mc Master University, Hamilton, Ont.
[3] Dept. Clin. Epidemiol./Biostatist., Mc Master University, Hamilton, Ont.
[4] Ctr. Res. Ctr. Hosp. Univ. Quebec, Departement de Medicine, L'Universite de Laval, Quebec, Que.
[5] Department of Geriatrics, Baycrest Centre for Geriatric Care, University of Toronto, Toronto, Ont.
[6] Father Sean O'Sullivan Res. Centre, St. Joseph's Hospital, Hamilton, Ont.
[7] Department of Sociology, McMaster University, Hamilton, Ont.
[8] Department of Microbiology, Mount Sinai Hospital, Toronto, Ont.
[9] Dept. of Lab. Med. and Pathobiology, University of Toronto, Toronto, Ont.
[10] Winnipeg Health Sciences Centre, Department of Medicine, University of Manitoba, Winnipeg, Man.
[11] Hamilton Hlth. Sciences Corporation, Department of Medicine, McMaster University, Hamilton, Ont.
[12] Department of Microbiology, Sunnybrook/Women's Coll. Hlth. S. C., Toronto, Ont.