406 Tetanus 



Immunity. All animals are not alike susceptible to 

 tetanus. Men, horses, mice, rabbits, and guinea-pigs are 

 susceptible; dogs much less so. Cattle suffer chiefly after 

 accouchement, and after abortion. Most birds are scarcely at 

 all susceptible either to the bacilli or to their toxin. Am- 

 phibians and reptiles are immune, though it is said that frogs 

 can be made susceptible by elevation of their body-tempera- 

 ture. 



Antitoxin. By the gradual introduction of tetanus toxin 

 Behring and Kitasato * have been able to produce a power- 

 ful antitoxic substance in the blood of animals. 



The method of obtaining tetanus antitoxic serum is much 

 like that employed for securing diphtheria antitoxic serum 

 (q. -v.), except that a longer time is required for immunizing 

 the animals, and that the doses of toxin administered are 

 of necessity smaller because of its greater activity. Horses, 

 dogs, and goats may be used for the purpose. 



Madsen f found that for each of the specific poisons, 

 tetanolysin and tetanospasmin, a specific antitoxin is pro- 

 duced, the one annulling the convulsive, the other the 

 hemolytic properties of the toxin. 



As tetanus is not a common affection, and the antitoxic 

 serum, like most immune serums, is not permanent, Tizzoni 

 and Cattani,{ who have experimented extensively upon the 

 subject, have successfully prepared it in a solid form, in 

 which, it is claimed, it can be kept indefinitely, shipped 

 any distance, and used after simple solution in water. 

 The method consists in precipitating the antitoxin from 

 the blood of immunized dogs with alcohol. 



The strength of the serum is usually expressed i : 1,000,000, 

 i : 10,000,000, etc., which indicates that i c.c. of the serum 

 is capable of protecting 1,000,000 or 10,000,000 grams of 

 guinea-pig from infection. 



Behring and Knorr have introduced an arbitrary unit 

 by which antitoxic strength of the tetanus serum can be 

 expressed. It is difficult to define in plain terms, but seems 

 to be the least quantity of the serum that will protect a 250- 

 gram guinea-pig against 1,000,000 fatal doses of fresh toxin. 



* " Deutsche med. Wochenschrift," 1890, No. 49. 

 t "Zeitschrift fur Hygiene," 1899, xxxm, p. 239, 

 I" Berliner klin. Wochenschrift," 1893 and 1894: "La Riforma 

 Medica," 1892 and 1893; "Centralbl. f. Bakt.," etc., 1890-91. 

 "Zeitschrift fur Hygiene," 1893, xm, p 407. 



