44S THE HEMORRHAGIC SEPTICEMIA GROUP 
Transmission of Plague.— The Interim Report of the Advisory 
Committee for Plague Prevention in India^ contains an excellent 
summary of the mechanism of plague transmission by the flea. In 
bubonic plague, the most common type seen in man, the plague bacilli 
are locked up in the body, as it were, and cannot of themselves escape 
to other hosts. The rat is usually the source of infection in plague 
epidemics, and rat fleas, Xenopsyllus cheopis, transmit the disease 
from rat to rat and from rat to man. When the host dies (rat or man) 
its ecto-parasites escape if possible to living hosts. It was shown by 
the Indian Commission- that fleas from plague-infected rats frequently 
contained large numbers of plague bacilli in their intestinal tracts, 
and that the bacilli were present at least three weeks after the last 
feeding. In the absence of fleas no infection takes place, at least in 
man. The bite of the infected flea may result in infection, or, since 
the feces of the flea laden with plague bacilli, are usually deposited 
during feeding, the irritant flea bite may lead to scratching of the area, 
resulting in the "rubbing in" of the bacilli deposited with the flea 
feces. Epidemics of pneumonic plague are spread by droplet infection. 
Preventive measures include the appropriate care of the patient and 
measures to reduce the rat population. This is accomplished by careful 
disposal of all garbage, rat proofing all houses and granaries, and an 
activfe campaign against rats by poison, destruction of nests and run- 
ways, and the creation of rodent-free zones of considerable magnitude 
around settlements. 
Bacteriological Diagnosis.— Human.— The juice of buboes,^ of lymph 
glands, of petechise, the blood, the sputum from pneumonic cases, 
and occasionally the urine contain plague bacilli in large numbers. 
Albrecht and Ghon^ have isolated plague bacilli from 5 urines out of a 
total of 17 examined. They may be obtained readily from the spleen, 
liver, lungs and kidneys of the cadaver. 
Animal.— The postmortem appearance of plague-infected rats is 
very characteristic. 
Microscopical Diagnosis.— The presence of Gram-negative, ovoid, 
short bacilli showing bipolar staining in considerable numbers in 
films prepared from material outlined above is very suggestive, but not 
conclusi\e cA'idence of infection with B. pestis. In man the evidence 
is stronger than in rats, for in the latter B. pseudotuberculosis roden- 
tium, B. tulara?nse, and other organisms may be present which produce 
lesions superficially not unlike those of plague. 
Cultural Diagnosis.— Prepare agar plates from the contents of 
enlarged glands or other material, incubate at 30° C. (or 37° C), 
1 Jour. Hyg., 1910, 10, 315. 
2 See Jour. Hyg., 1906, 1907, 1908, 1910, for a discussion of the relation of fleas to the 
transmission of plague. 
3 Buboes which have suppurated frequently either do not contain plague bacilli, or 
plague bacilli in association with extraneous organisms. Even if buboes have not 
developed, the lymphatic glands usually contain the bacilli. 
* Centralbl. f. Bakteriol., 1899, 26, 362. 
