147 



of 1903-4. There occurred 160 cases with 77 deaths, the last case 

 appearing January 30, 1908. The following table shows the inci- 

 dence of human plague: 



EPIDEMIOLOGICAL OBSERVATIONS IN SAN FRANCISCO. 



Abundant epidemiological data associating the rat a with plague 

 have been collected in San Francisco. For the purpose of illustration 

 a detailed reference to a few cases will be made. Two small boys 

 (October, 1907) while playing in an unused cellar found the body of a 

 dead rat. The corpse was buried with unusual funeral honors. 

 In forty-eight hours both were ill with bubonic plague. A laborer 

 finding a sick rat on the wharf picked it up with the naked hand and 

 threw it into the bay. He was seized three days later with plague. 

 Doctor C. and family lived in a second-story flat over a grocery store 

 in the residence section. Being annoyed for some days by a foul 

 odor the doctor caused the wainscoting around the plumbing to be 

 removed. One or two rat cadavers were found in the hollow wall. 

 In two or three days the two members of the family who used the room 

 sickened, one dying on the fifth day of cervical bubonic plague. It 

 is probable that infected rat fleas were set free by the removal of 

 the wainscoting. 



Dead rats were frequently found in or near houses where plague 

 had occurred. Immediately upon the discovery of a case of plague 

 trained men were sent into the neighborhood and a thorough search 

 made for rats. This work consisted in the removal of defective 

 wooden floors and walls of insanitary buildings and other harboring 

 places. Extensive rat catacombs were frequently found in these 

 operations. In the yard of a house in which 4 cases had occurred 

 20 cadavers were found under the board covering. In the walls of 

 a Chinese restaurant 87 dead rats were uncovered. 



a M. norvegicus and M. rattus. 



