1. Central Animal Laboratory, Catholic University of Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
2. Department of Otorhinolaryngology, Catholic University of Nijmegen, P.O. Box 9101, 6500 HB Nijmegen, The Netherlands
3. Department of Animal Supply, Laboratory for Parasitology and Mycology, National Institute of Public Health and Environmental Protection, P.O. Box 1, 3720 BA Bilthoven, The Netherlands; Department for Laboratory Animal Bacteriology, Laboratory for
Parasitology and Mycology, National Institute of Public Health and Environmental Protection, P.O. Box 1, 3720 BA Bilthoven, The Netherlands
4. Department for Laboratory Animal Bacteriology, Laboratory for Parasitology and Mycology, National Institute of Public Health and Environmental Protection, P.O. Box 1, 3720 BA Bilthoven, The Netherlands