CAUSE. Plague is not caused by filth, over crowding, diseased grain, or inundations. It is always caused by the presence of the plague bacillus, or Bacillus pest is. The micro6rganism was discovered independently by Kitasato and Yersin in 1894. It is a small oval rod, short and thick, with rounded ends that take stain more readily than the central portion, showing the 'pole staining.' The bacilli are found in pairs or singly. and, in cultures, arranged in chains. They do not form spores and are motile. They occur in enormous numbers in the smaller glands (buboes), in the spleen, and after death in the blood. The lower animals, especially rats, are infected in large numbers from the dust in pest-laden houses. The unsanitary conditions under which the affected individuals live give ample opportunity for the direct or indirect transmission of the disease from patient to patient. Flies and other insects carry it. (See INSECTS, PROPAGATION OF DISEASES BT.) Kita sato considers that the bacillus may enter the body by the skin surface, through cracks or wounds, by the respiratory passages, or by the alimentary canal.
Sy AIPVMATOLOGY. Two forms of the dread disease are described—pcstis major and pcstis minor. Pest is minor includes various patholog ical conditions, all of favorable prognosis, pre sumed to be caused by the plague infections. Slight fever, slight swelling of the glands, or local tenderness with trivial systemic involvement. eon stitute the attack. In other cases, prostration, headache, vertigo. and gastrointestinal disturb ance, occur. Those cases occurring in houses in which plague has been found. and during a plague epidemic, are considered to he related to the scourge: but no bacteriological examinations have verified the suspicions. Pest is major (the severe or ordinary plague) may he of one of the following five varieties: (1) Bubonic, (2) pneu monie, (3) septiexmic, 14) py(emic, or (5) local inoculation. An average attack of ordinary bubonic plague presents the following course: The period of inoculation lasts from three to seven days. The period of invasion, or prodromal period, varies from 24 to 48 hours in length, and during it the patient suffers with fever, weakness, lassitude, vertigo, headache, and vom iting. Bubo development follows, with stagger
ing gait, tremulous speech, and great restlessness; a temperature of 104° F. or higher; a full pulse, averaging 130 to the minute: a dry granular tongue covered with a yellow velvety fur, but with a red margin ; an anxious and pallid face: constipation; and the enlargement of glands in the neck, groins, or axillie, constituting the buboes. Following the appearance of the buboes occurs a fall in temperature and pulse rate. and this generally on the second or third day of the disease. After a remission of a little over two days, the fever ascends to 103° or 105° F., at which point it remains for seven days, during which time the bubo reaches its full development. After 10 days the temperature falls. Emacia tion and exhaustion are extreme. The patient may now die of heart failure, in syncope; or of hemorrhage, of peritonitis, of jaundice, of hyper rexia; or he may recover alter about two mouth.' convalescence. The Imbous often sup purate, or become necrotic. sometimes involving considerable areas of surrounding tissues. Some times foci of broneho pneumonia are found in the lungs. each focus surrounded by a congested pulmonary tissue. tiecosionally the alveoli are found full of sanguinolent fluid which is swarm ing with plague bacilli. Or, multiple abscesses and pulmonary infarcts arc noted. These cases in which lung involvement is prominent are called pneumonic plague.
Piy...costs, Morannirv, ANn :MORTALITY% In 1.1W vast majority of eases the prognosis of the disease is extremely unfavorable, much depend ing on the character of different epidemics. Sep tietemic :Ind pneumonic eases ar almost always fatal. After convalescence, weakness and a neur asthenia may persist for a long period. The rate of mortality varies much. In certain en demics from one-half to three-quarters of an entire population has perished. In the Hong Kong epidemic of 1894 the mortality was 95 per cent. In Bombay during 1896 and 1897 it was 50 to 60 per cent., while during 189S to 1901 it averaged SO per cent.