1. Ontario Ministry of Natural Resources, Wildlife Research Section, P.O. Box 5000, Maple, Ontario, Canada L6A 1S9
2. The authors are listed in alphabetic order, in recognition of varied contributions from a team with diverse talents
3. Present address: R.R. 1, Cheltenham, Ontario, Canada L0P 1C0
4. Department of Microbiology and Immunology, University of Toronto, Toronto, Ontario, Canada M5S 1A1
5. Present address: Box 1132, Red Lake, Ontario, Canada P0V 2M0
6. Connaught Laboratories Limited, 1775 Steeles Ave. West, Willowdale, Ontario, Canada M2R 3T4
7. Present address: Aviation, Fire and Forest Resources Branch, 747 Queen Street, Sault Ste. Marie, Ontario, Canada P6A 5M7
8. Present address: 20 Preston Place, Toronto, Ontario, Canada M4N 2S9