Although contagious abortion of cattle and other domestic animals has long been known to be a serious economic problem, and the possibility of human infections with the causal organism has been long in the minds of investigators, it is less than five years ago since the first human case of infection with this organism was recognized. Since then, a number of cases have been recognized in this and other countries. It is now an established fact thatBrucella melitensisvarietyabortusmay infect man. The disease of man contracted from cattle or hogs is indistinguishable clinically from that prevalent in Mediterranean countries and known as undulant, or Malta fever. In Mediterranean countries it is contracted from goats by consuming infected milk or cheese, or by handling infected goats or infected goat meat, or from contaminated soil or dust. In this country, although the animal host is not the same as