248 PUBLIC HEALTH BACTERIOLOGY 



adrenals. Cats, dogs, and pigeons are very susceptible to 

 mucus infection ; rats and mice are refractory. 



A guinea-pig killed by the injection of a virulent culture 

 of diphtheria bacillus shows congestion of all the organs, 

 especially severe in the suprarenals. 



Toxins. Diphtheria toxin is an extracellular one, that 

 is, it is soluble in the liquid media, and can be obtained 

 separate from the bacillus by filtration through a Chamber- 

 land tube. Toxin formation is best got in meat-infusion 

 broth with added peptones, and rendered alkaline, after 

 two to three weeks' growth at 37-5 C. A free supply of 

 oxygen is important to secure the greatest toxin formation. 



The toxin is readily destroyed by bright light, by 

 exposure in a liquid solution to 6o C, or if in dry state 

 to a temperature over 70 C. Sealed and kept in the dark 

 and in the cold, it may be kept for long periods. It is 

 believed to be closely allied to the albumoses. 



Antitoxin. The mode of preparation and standardiza- 

 tion is described under Antitoxic Sera (page 189). The 

 value of antitoxin in the treatment of diphtheria is now 

 well attested. The results are better the earlier the injec- 

 tion, so that few deaths occur in those injected within 

 twenty-four hours of the onset, the rate gradually rising 

 until by the fifth day the effect is slight. The dose 

 given is not proportionate to the age, but to the severity 

 of the attack and the time that has elapsed before 

 coming under treatment. 2000 to 8000 units should be 

 given to children on these principles, and up to 50,000 

 units have been given in one case. In large doses, it is 

 better to give the higher-potency sera, in which 10,000 

 units can be had in 10 c.c. of serum. In about one-third 

 of the cases injected, serum sickness or serum disease is 

 noted. The symptoms are : an erythematous rash and 

 fever coming on in a week to ten days after the injection. 

 At times general pains and even arthritis may be present. 

 These symptoms are more likely to be produced by large 

 doses of serum. But more alarming symptoms than these 

 occur soon after the injection, as has been referred to 

 under Anaphylaxis (page 212). On analysis these cases 

 are found to occur in people who have not been previously 

 injected, and in people who have had a previous injection 



