System for the timely detection and identification of an incursion or emergence of diseases or infections in a country, zone or compartment. An early detection system should be under the control of the Veterinary Services and should include the following characteristics: -representative coverage of target animal populations by field services; -ability to undertake effective disease investigation and reporting; -access to laboratories capable of diagnosing and differentiating relevant diseases; -a training programme for veterinarians, veterinary paraprofessionals, livestock owners/keepers and others involved in handling animals for detecting and reporting unusual animal health incidents; -the legal obligation of private veterinarians to report to the Veterinary Authority;-a national chain command.