264 THE INFECTIOUS DISEASES. 



Characteristic tetanic symptoms followed by death may be induced in mice, guinea- 

 pigs, and rabbits by subcutaneous inoculation of cultures. Man and the horse are 

 markedly susceptible to tetanus ; birds are as a rule insusceptible. If the tetanus ba- 

 cillus be grown in nutrient broth at blood heat out of contact with oxygen the toxin is 

 developed and mingles with the fluid. This toxin when freed from living germs is 

 capable of inducing the symptoms of the disease. Broth cultures may after some 

 weeks have acquired such an extreme intensity that the dried poisonous material, sep- 

 arated from the inert fluids and partially purified, may be fatal to a mouse weighing 15 

 gm. in a dose of 0.00000005 gm. Estimating according to the relative weights of the 

 subjects, the minimal fatal human dose would be about 0.00023 gm. This toxin is ren 

 dered inert by a temperature above 65 C. and by light. 



TETANUS ANTITOXIN. 



By procedures similar to those described in diphtheria immunization 

 (p. 175), the tetanus toxin has been used to secure artificial immunity in 

 dogs, goats, and horses, and here also the blood serum of the immunized 

 animals has been prepared and employed in man 

 for therapeutic purposes with some degree of suc- 

 cess. The theoretical promise of the tetanus an- 

 titoxin for therapeutic purposes in man is, how- 

 ever, in practice rendered in large measure futile, 

 because the existence of the disease is not recog- 

 FIG i&5 -BACILLUS TETANI. niz able until the toxseniia is sufficiently marked to 

 Fromacuiture; showingciub^ P rodu ce the nervous symptoms, at which time an 

 shaped ends with spores. enormous and not easily determined dosage is re- 

 quired to neutralize or counteract the effects of 



the already elaborated poison. Statistics are as yet too meagre to jus- 

 tify a final opinion as to the practical value of serum therapy in 

 tetanus, but it appears to be definitely useful. ' 



Diagnosis. 



For purposes of diagnosis it may be necessary to inoculate a white mouse at the 

 base of the tail with suspicious material at the same time that morphological examina- 

 tion and anaerobic cultures are made. Should tetanus develop in the mouse within a 

 few days control cultures may be made from the exudate at the seat of inoculation. 2 



Other Bacilli of the Tetanus Group. 



Several bacterial species are already known which may be classed in the tetanus 

 group. While varying in size, these bacilli are in general rather large ; spores form in 

 their thickened ends; they are facultative anaerobes; some do, others do not fluidify 

 gelatin, and they retain the stain b}' Gram's method. They are mostly saprophytes 

 and have been found in milk and milk products, in excrement and sewage, etc. None 

 are known to be pathogenic in man. The most noteworthy among these is Bacillus 

 pseudo-tetamcus, Sanfelice, which in morphology and growth characters resembles the 

 Bacillus tetani, but it does not form the toxin. 



1 For a critical resume of tetanus and its treatment with the antitoxic serum, with 

 bibliography, see Moschmwitz, Annals of Surgery, vol. xxxii., p. 219, 1900. 



2 For resume of characters of the tetanus bacillus and its toxin see von Lingelshfim, 

 Kolle and Wassermann's "Handbuch der Mikroorganismen," Bd. ii., p. 566. 



