Etiology and Pathology of Rat-bite Fever

Our knowledge of the causative agent of rat-bite fever is of recent date. Futaki and his associates reported in their first communication the finding of a long spirochete, measuring 9 to I0/z in the lymph glands on the 10th or 13th day of illness, and on the 33rd day in tissue fluid obtained from the bitten area. Those found in the lymph exudate had small waves, those from sections of lymph glands, numerous steep waves. Later on they discovered in man, in the wound of the rat bite, and in the blood of mice which had received injections of patient's blood, shorter, thick spirochetes, 2 to 6 ~ long. These had regular, close, and steep waves, and a filament at each end. As these long and short spirochetes are morphologically distinct, and both have been demonstrated in ratbite fever, the question arose whether they are of the same species, or whether rat-bite fever may be caused by two different spirochetes. The problem could not be solved at the time by Futaki and his coworkers. In the meantime, Ishiwara and his associates found in their investigations of experimental rat-bite fever spirochetes of the shorter variety, which were morphologically identical with the short variety of Futaki. Kitagawa and Mukoyama, as well as Midzukuchi, reported finding these spirochetes in experimental rat-bite fever.