616 ANAPHYLAXIS IN RELATION TO INFECTION AND IMMUNITY 



certain food or foods from the diet of hypersensitive persons has resulted 

 in an improvement or cure of an eczema. 



The diagnosis of food idiosyncrasy may be made on the basis of the 

 experience of the patient that the ingestion of a certain food is followed 

 by the occurrence of certain symptoms. Cutaneous and intracutaneous 

 skin tests have also been employed, and apparently with success. The 

 cutaneous tests are conducted by cleansing the skin of the arm with alcohol 

 and abrading a small area of skin with a needle or von Pirquet borer. 

 A small amount of the food, as a drop of egg-white or a drop of a 5 per 

 cent, watery solution of the food, is now applied and rubbed into the 

 abraded skin. A control test should be made with salt solution or water 

 alone, as persons with an irritable skin may react with slight edema and 

 erythema to the trauma. A positive reaction is indicated by the develop- 

 ment of a well defined urticarial wheal surrounded by a zone of erythema 

 and similar to the cutaneous serum reaction shown in Fig. 123. The 

 reaction appears within five to ten minutes and lasts from twenty to 

 forty-five minutes. 



The intracutaneous test is more delicate but somewhat more painful 

 and likely to yield confusing and non-specific reactions. It consists 

 in the intracutaneous injection of a very minute amount of a sterile 

 solution of the protein of the food; usually 0.1 c.c. of 0.1 per cent, solu- 

 tion suffices. The reactions should not be read until after the elapse of 

 forty-eight hours, as non-specific reactions may be observed during the 

 first twenty-four hours after injection. Positive reactions are indicated by 

 the formation of a tender papule with well-marked edema and erythema. 



As a general rule a series of tests with different foods may be done 

 with the skin of both arms; soluble proteins of various foods are marketed 

 in a convenient form for the tests. 



The treatment of food idiosyncrasy consists in the withdrawal of the 

 food from the diet and attempts toward desensitization by feeding the 

 food in very small and non-toxic doses until the skin reaction disappears 

 or becomes very weak. If a person is very sensitive it is well to begin . 

 with a dose of less than 0.01 gram three times per day, gradually in- 

 creasing until the food may be ingested without apparent harm. The 

 process of desensitization, however, is prolonged, and in my experience 

 has not been accomplished in several cases of extreme hypersensitiveness 

 to egg-albumen. Attempts have also been made to desensitize by sub- 

 cutaneous injections of a sterile solution of the particular protein con- 

 cerned. The initial doses should be small and approximately the smallest 

 amount capable of eliciting an intracutaneous reaction. 



4. Certain drugs, such as iodoform, iron citrate, and even atropin, 



