558 Plague 



The German Plague Commission* believed that an important 

 improvement in the vaccine could be brought about by the use of 

 the method now generally employed in making bacterio-vaccines 

 (q.v.). They therefore caused the bacilli to grow in Roux bottles 

 upon the surface of agar-agar for forty-eight hours, washed off the 

 bacteria with bouillon or physiological salt solution so that i cc. of 

 the suspension contained about 2.5 mg. of bacilli, and then heated the 

 suspension for an hour or so at 65C. After heating, 0.5 per cent, 

 of phenol was added. This mode of preparation has the advantage 

 of excluding the possibility of the accidental growth of tetanus bacilli 

 and other micro-organisms in the culture. The vaccine appeared to 

 give excellent results in Brazil where it was extensively used. 

 Haffkine, however, considers his method preferable because of the 

 greater quantity of immunizing metabolic products of the bacilli 

 contained in the fluid cultures on account of their prolonged growth. 



The immunity conferred by the Haffkine prophylactic is supposed 

 to last about a year. The preparation must never be used if the 

 person has already been exposed to infection, and is in the incuba- 

 tion stage of the disease, as it contains the toxins of the disease, and 

 therefore greatly intensifies the existing condition. When injected 

 into healthy persons it always produces some fever, slight local 

 swellings, and malaise. 



Kolle and Ottof from experimental studies of plague immunity 

 in rats, came to the conclusion that a prophylactic injection con- 

 sisting of a culture of attenuated plague bacilli would have a much 

 more powerful and lasting effect than one consisting of a killed 

 bacilli. The same conclusion was reached by Kolle and Strong! 

 and the first use of living cultures for preventive inoculation in 

 human beings was byStrongwho found them to be devoid of danger, 

 and is hopeful regarding their efficacy. 



Besredka|| advises the use of a killed culture sehsitized by the 

 application of immune serum. Such vaccine seems to be productive 

 of long enduring immunity when tried upon experimental animals. 



Rowland** is under the impression that the essential immunizing 

 antigen is in the bacterial nucleoproteins. These he extracts from 

 the bacterial cells by treating them while moist with anhydrous 

 sodium sulphate, freezing, permitting the water to be absorbed by 

 the chemical, thawing, and then filtering off the fluid at 37C. The 

 filtrate thus obtained is highly toxic, fatal to rats in minute doses and 

 capable of effecting immunization. 



II. Passive Immunity against plague, through the employment 



* "Arbeiten aus dem Kaiserl. Gesundheitsamte," 1899, xvi. 

 t" Deutsche med. Wochenschrift," 1903, p. 493; "Zeitschrift fur Hygiene," 

 1903, XLV, 507. 



"Deutsche med. Wochenschrift," 1906, xxxii, 413. 

 "Jour. Medical Research," N. S., 1908, xvm, 325. 

 "Bull, de 1'Inst. Pasteur," 1910, vin, 241. 

 ! * "Jour, of Hygiene," 1912, xu, 344. 



