A TEST FOR IMMUNITY 



453 



this mixture, but his work was interrupted by the World War. 

 Later, Dr. WilUam H. Park of the New York City Laboratories, 

 inoculated children with the antitoxin and toxin, known as toxin- 

 antitoxin, and was successful in having them develop an active 

 immunity which was permanent. 



A test for immunity. Li 19L3, Dr. Bela Schick devised the 

 Schick test of susceptibility. When small quantities of toxin are 

 put under the skin of children, the reaction will indicate whether 

 the child is naturally immune or not. If naturally immune, the 

 toxin will be neutralized by antitoxins in the blood and no effect 

 is produced. If not immune, a slight local irritation results in 

 the form of a red spot which appears and disappears within a def- 

 inite time period. It indicates that there are not sufficient anti- 

 toxins in the blood to neutralize the small amount of toxin injected. 



Cause of diphtheria. Diphtheria (sometimes called '^ mem- 

 branous croup ") is justly regarded as one of the most dreaded of 

 the diseases of childhood. It is a disease of temperate climates, 

 occurring most frequently in the colder months. In cities, the 

 disease is always more or less prevalent; in rural communities, it 

 is more likely to occur in 

 epidemics. 



Deaths from diphtheria 

 occur chiefly among chil- 

 dren less than five years 

 old. There is a definite 

 increase in susceptibility 

 to the disease during the 

 first two years of life, 

 and a gradual develop- 

 ment of immunity there- 

 after, especially if the 

 individual lives in a well- 

 populated district and is more or less exposed to the disease. 



Am. Ass. for Med. Frog. 



Note that the ages of greatest susceptibility to diph- 

 theria is among the pre-school children group. This 

 is where the greatest prevention work should be done. 



