BACILLUS TETANI 481 



The Tetanus Antitoxin Unit. The tetanus antitoxin unit of the 

 United States may be defined as "ten times the minimal quantity of 

 tetanus antitoxin necessary to protect a 350-gram guinea-pig against 

 a standard dose of tetanus toxin obtained from the United States 

 Public Health and Marine Hospital Laboratory." It has theoretically 

 the power to neutralize one thousand minimal lethal doses of tetanus 

 toxin, and it has, consequently, ten times the theoretical strength of 

 the diphtheria antitoxin unit. 



Distribution of Tetanus Bacilli in Nature. Under ordinary con- 

 ditions the tetanus bacillus appears to be a saprophyte, and man is 

 not necessary for its continued existence. The organisms are found 

 very commonly in the excrement of the herbivora, notably horses and 

 cattle. 1 Sormani 2 has even claimed that the virulence of the tetanus 

 bacillus is maintained by frequent passages of the organism through 

 the intestines of the herbivora. Pizzini 3 has found tetanus bacilli 

 in the feces of peasants who tended horses. Not all observers, however, 

 subscribe to the intestinal theory. Hoffmann, 4 for example, found 

 the organism only once out of twenty-two samples of feces from twenty- 

 two different horses. 



Tetanus spores are found widely distributed in nature, particularly 

 in the upper layers of the soil; in temperate climates their distribution 

 is somewhat irregular, but in the tropics they appear to be very widely 

 disseminated. Tetanus spores also occur in gelatin occasionally, and 

 they have even been detected in cat gut. Levy and Bruns, 5 and 

 Anderson 6 have all found tetanus spores in commercial gelatin. The 

 potential dangers attending the use of gelatin as a hemostatic are 

 apparent. 7 Tetanus spores have also been found in vaccine virus in 

 the past, 8 and Carini 9 has found spores in vaccine virus; and at least 

 two outbreaks of tetanus, one in this country and one in Europe, have 

 resulted from the infection of diphtheria antitoxin with tetanus spores. 

 Rabinovitch 10 has also found tetanus spores in washings from straw- 

 berries sold in Berlin. 



1 Sanchez, Toledo, and Baillon, La Semaine Med., 1,890, No. 45; Centralbl. f. Bakt. 

 1890, ix, 18. 



2 Behand. der 10th Intern, med. Kong., Berlin, 1890, v, 152. 



3 Riv. d'igiene e san. publ., 1898, x, 170. 



4 Hyg. Rund., 1905, xv, 1233. 



5 Grenzgeb. der Med. u. Chir., 1902, x, 235; Deutsch. med. Wchnschr., 1902, 130. 



6 Mar. Hosp. Lab. Bull., 1902, ix. 



7 Zibell, Munchen. med. Wchnschr., 1901, 1643, for literature. 



8 McFarland, Lancet, September, 1902. 



9 Centralbl. f. Bakt., Orig., 1904, xxxvii, 48. 



10 Arch. f. Hyg., 1907, Ixi, 103. 



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