152 BACTERIOLOGY FOR NURSES 



Prophylaxis. — Vaccination against cholera has 

 been successfully practiced in India for some years. 

 Guinea-pigs are immunized by repeated intraperito- 

 neal injections of small doses of spirilla until a high 

 degree of immunity is attained. If the blood- 

 serum from the immunized guinea-pig be injected, 

 with a fatal dose of the virulent spirilla, into a suscep- 

 tible guinea-pig, it is found that a small dose of the 

 immune blood-serum will protect the susceptible 

 animal against a ten times fatal dose of virulent 

 spirilla. The immunized blood-serum dissolves (bac- 

 teriolysis) the spirilla, the phenomenon being known 

 as "Pfeiffer's reaction." The blood-serum of an 

 immunized animal has also an agglutinative action 

 against the cholera spirilla, analogous to Widal,'s 

 reaction in typhoid fever. 



Haffkine's vaccination against cholera, which is 

 employed so extensively in India, is carried out in 

 accordance with these principles and has proved to be 

 successful. 



Powell gives the following statistics: — 



Number Cases Deaths 



Unvaccinated 6549 198 124 



Vaccinated 5778 27 14 



Besides vaccination for the prevention of cholera, 

 the careful observance of quarantine, particularly 



