1. The University of Sydney, Department of Veterinary Clinical Studies, Camden, Australia
2. Epidemiology and Field Studies Branch, National Institute of Arthritis, Metabolism and Digestive Diseases, Phoenix, Ariz.
3. Pasteur Institute, Noumea, New Caledonia
4. Institut d'Elevage et de Medecine Veterinaire en Pays Tropicaux, Noumea, New Caledonia