Is a specific infectious disease of horses that is sometimes seen in man as the result of accidental infection.

Is caused by the Bacillus mallei, a non-motile, non-sporu-lating, aerobic or optionally anaerobic bacillus 2 to 5 in length. Is pathogenic for man and lower animals. Stains by ordinary methods, but not by Gram's. Grows on ordinary media, but best on glycerin agar.

It makes its appearance in the membrane of the nose in horses in the form of small nodules the size of a pea. These may increase in size, but eventually break down and ulcerate, with the formation of irregular ulcers, having yellowish, elevated, and indurated borders from which some bloody pus is discharged. Lymph-nodes become enlarged, and metastatic abscesses may result. The lungs are frequently involved and macroscopically resemble a tuberculous bronchopneumonia.

Microscopically the nodules consist of masses of small round cells and epithelioid cells. Do not find giant cells.

If the skin is involved the condition is known as "farcy," and the nodules as "farcy buds." They generally undergo central necrosis and suppuration with very extensive ulceration.

Man may become infected through lesions of the mucous membranes of the eye or nose or of the skin, and the result is usually fatal. The course is that of an acute febrile affection suggesting typhoid fever.

Fig. 33. - Bacillus Mallei, from a Culture upon Glycerin Agar-agar. X 1000 (Frankel and Pfeiffer).