The Dick Reaction and Scarlet Fever Morbidity following Injections of a Purified and Tannic Acid Precipitated Erythrogenic Toxin

Abstract

The purpose of this study was to de-termine the value of small intradermal doses of purified and tannic acid precipitated scarlet fever streptococcus toxin in causing the Dick reaction to become negative and in preventing subsequent attacks of scarlet fever. Dick tests were made on 11,140 persons in the age group 5 to 16, both inclusive: the 6-yr.-old group showed 56.1% Dick positive, the 14-yr.-old group gave only 28.8% positive, without the benefit of any artificial immunization. 3 intradermal doses of 0.1 cc. each of the antigen (750, 3000 and 10,000 STD) with a 2-week interval were practicable. Subse-quent Dick tests showed that 85-90% of those treated developed a Dick-negative reaction. Additional tests from 44-47 months later showed no loss in immunity. Even smaller doses proved sufficient to immunize a high % of those treated. The influence of such immunizations on the incidence of scarlet fever was observed over a period of 4 yrs. in a total of 41,109 person-years as compared to a similar control group. In the 6-9 age control group the annual attack rate was 9.29 per 1000 as against 1.47 in the treated Dick positive group. In the 10-15 group the corresponding rates were 3.15 and 0.66. The failures occurring within the treated group fall within the calculated expectancy on the basis of 85-90% becoming immune following the immunizing injns. A few failures also occurred in the group giving a negative Dick reaction without previous injections of immunizing toxin.