Undulant fever is caused in Britain by infection with brucella abortus which is usually spread to man by the ingestion of raw milk from infected cattle. It is also an occupational hazard of veterinary surgeons, laboratory personnel, slaughter house workers and others. In Malta, the disease is due to Br. melitensis and is transmitted by infected goat’s milk. In the USA and the Far East Br. suis acquired from pigs may be the causative organism. The disease is not notifiable. The incubation period is about three weeks.