48 BACTERIOLOGY 



in or extends into the larynx, the condition is called 

 membranous croup or laryngeal diphtheria. The mem- 

 brane may close the larynx and death from suffocation 

 result unless intubation or tracheotomy is performed. 



Prevention of Infection. An absolutely certain pre- 

 ventive of infection is an immunizing dose of antitoxin. 

 An injection of from 1000 to 3000 units is considered 

 sufficient for immunization, while curative doses range 

 from 3000 to 20,000 units, depending on the severity 

 of the case and the stage at which the antitoxin is ad- 

 ministered. 



A rare and curious condition exists in some individuals, 

 in which the person is said to be sensitized to horse- 

 serum. In such persons, who are frequently asthmatics, 

 the administration of antitoxin may give rise to severe 

 asthmatic paroxysms, cardiac weakness, suspension of 

 respiration, and even death. It is a remarkable thing 

 that most of such people are frequently thrown into 

 asthmatic paroxysms by the presence of a horse or the 

 odors of horses. 



Bacillus Typhosus (Bacillus of Eberth). A ^Bl-motile, 

 facultative anaerobic bacterium. There is practically 

 but one source of infection, the feces or urine of a typhoid 

 patient, and one avenue of infection, the digestive tract, 

 so that to have typhoid fever one must virtually eat 

 some one's excreta, no matter with what dish it may be 

 served. A contaminated water-supply is the greatest 

 agent of infection. 



