1. Department of Virology, Immunobiology and ParasitologyNational Veterinary InstituteUppsalaSweden
2. Department of Veterinary Epidemiology and Public HealthUniversity of SurreyGuildfordUK
3. Department of Clinical SciencesSwedish University of Agricultural SciencesUppsalaSweden
4. Equine Hospital SolvallaStockholmSweden
5. Department of Disease Control and EpidemiologyNational Veterinary InstituteUppsalaSweden