Epidemiology and management of a bovine brucellosis cluster in Northern Ireland

An epidemiological investigation was undertaken of 41 bovine brucellosis outbreaks that occurred within a 10-month period, in a region where eradication measures appeared to be succeeding. The primary outbreak comprised three herds with significant within-herd spread and a high probability of multiple abortions. Direct contact between cattle at pasture was the most likely means of between-herd transmission for most (71%) outbreaks, with an attack rate of 28.1% in herds immediately neighbouring the primary outbreak herds and 11.3% in the next concentric ring of farms. Resolution of the incident was attributed to a rapid response by the veterinary authorities, detailed epidemiological investigations, repeated, prolonged testing of contact herds and employment of parallel testing.