1. Environment and Natural Resources Area, IASMA Research and Innovation Centre, Fondazione E. Mach, Via E. Mach 1, S. Michele all'Adige, Italy
2. Apodemus AB, Grevgatan 38, SE-114 53 Stockholm, Sweden
3. Department of Medical Cell Biology, Uppsala University, Box 571, SE-751 23 Uppsala, Sweden
4. Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna, Sezione Diagnostica Provinciale di Sondrio, via Bormio 30, 23100 Sondrio, Italy
5. School of Public Health, University of California, 140 Warren Hall, Berkeley, California 94720-7360, USA
6. Public Health Institute, Oakland, California 94607-4046, USA