Zoonotic diseases spread from animals to humans. Brucellosis is caused by Brucella species and spreads through infected milk, contact with aborted fetuses, or discharges. It causes undulant fever in humans. Control measures include testing animals regularly, culling infected ones, vaccination (e.g., S19 in calves), and strict hygiene. Farmers should always boil or pasteurize milk before consumption to prevent transmission.