596 Plague 



should also be kept in quarantine before mingling with 

 society. It is much more easy to keep plague out of a 

 port than to combat it when it has entered, for under the 

 latter condition are involved the isolation of the patients 

 in rat-free and vermin-free quarters, the disinfection of 

 the premises and goods where the case arose, and an im- 

 mediate warfare upon the rats and other small animals of the 

 neighborhood. To emphasize how difficult the latter may be 

 it is only necessary to point out that plague reached San 

 Francisco in May, 1907, during which year there were 156 

 cases and 76 deaths. Every precaution was taken to prevent 

 its spread, and extermination of rats, many being found 

 infected, practised. Though at great expense and with the 

 utmost thoroughness the rats were destroyed, the plague 

 spread to the ground squirrels and other small rodents, and in 

 1911 plague-infected rodents were still to be found in the 

 outskirts of the city. 



Immunity. An attack of plague usually exempts from 

 future attacks. Kitasato's experiments first showed that it 

 was possible to bring about immunity against the disease, and 

 Yersin, working in India, and Fitzpatrick, in New York, 

 have successfully immunized large animals (horses, sheep, 

 and goats). The serum of the immunized animals contains 

 specific agglutinins and bacteriolysins as well as an antitoxin, 

 capable not only of preventing the disease, but also of curing 

 it in mice and guinea-pigs and probably in man. 



Haffkine's Prophylactic. Haffkine* followed his plan 

 of preventive inoculation as employed against cholera, and 

 has invented a mode of prophylaxis based upon the use 

 of devitalized cultures. Bouillon cultures are used, and 

 small floating drops of butter are employed to make the 

 "islands" of plague bacilli float. The cultures are grown 

 for a month or so, successive crops of the island-stalactite 

 growth being precipitated by agitating the tube. In this 

 manner an "intense extracellular toxin" containing large 

 numbers of the bacilli is prepared. The culture was killed 

 by exposure to 70 C. for one hour, and used in doses of i to 3 

 c.c. as a preventive inoculation. 



An interesting collection of statistics, showing in a con- 

 vincing manner the value of the Haffkine prophylactic, is 

 published of Leumann, of Hubli. The figures, together 



* "Brit. Med. Jour.," June 12, 1897. 



