150 



rdle in the continuance of plague. This general revision has also 

 eliminated overcrowding as an important factor. In the absence 

 pneumonic cases, and of suctorial insects, this hete noire of the sani- 

 tarian may be disregarded. 



THE OCCURRENCE OF PLAGUE IN THE MARMOT OF ASIA AND THE 

 GROUND SQUIRREL OF CALIFORNIA. 



Rudenko (1900) first pointed out the possibility of contagion by 

 the "Tarbagan," a species of the arctomymas found in Siberia. He 

 observed a connection in 1894 between this rodent and an outbreak 

 of plague in a Cossack family of Soktuewsk. According to Beliatsky 

 and Zabolotny, each having been an observer in the same field, the 

 natives of Siberia and Mongolia often acquire plague in this manner. 

 Le Dantec and other writers have called attention to the probable 

 susceptibility of the marmot (Arctomyshohac), a hibernating rodent of 

 India and China. The marmot of Thibet, in the opinion of this writer, 

 is the natural animal host and purveyor of the virus. The literature 

 of the subject presents no bacteriological evidence, however, of such 

 a relationship, and plague in the arctomyinse of Asia is merely an 

 hypothesis. There is positive evidence though of the susceptibility 

 of the tree squirrel (Sciurinse) to plague infection. Dr. Alice Cor- 

 thorn (1898) reported the finding of a plague-infected squirrel in 

 one of the outbreaks in the Bombay Presidency. 



PLAGUE INFECTION IN GROUND SQUIRRELS.^ 



The demonstration of natural plague in the California ground 

 squirrel (OtospermopMlus beecheyi) is perhaps the most important 

 observation of the antiplague work of the service in 1908. The 

 existence of a plague epizootic in Contra Costa County was suspected 

 as early as the summer of 1903, and efforts were made at that time to 

 collect sick and dead rodents for bacteriological examination. In 

 August (1903) two fatal cases of human infection occurred in widely 

 separated sections of- the county. The investigation which followed 

 failed to connect either with a previous case of human plague, but 

 showed an association with ground squirrels. These deaths occurred 

 during a fatal epizootic among ground squirrels and suggested a con- 

 nection which unfortunately was not confirmed. 



None of the circumstances were forgotten, however, and in the 

 second campaign, begun in September, 1907, in San Francisco, 

 inspectors were detailed to examine all persons dying in the area 

 under suspicion. No plague was reported that autumn and winter. 

 Fatal cases occurred and were reported by the inspectors in July, 1908, 

 as follows: A boy (J. F.) died July 15, near Concord, and a young 



"Genus Citellus, Oken; subgenus Otoapermophilus. "California Mammals," 

 Frank Stephens. 



