Memorandum on immunological procedures which service personnel and their families may need at home and abroad.

  • Great Britain. Ministry of Defence.
Date:
1968
Catalogue details

Licence: Public Domain Mark

Credit: Memorandum on immunological procedures which service personnel and their families may need at home and abroad. Source: Wellcome Collection.

    40/132 (page 36)
    Section 10 Active immunization against diphtheria 90 Susceptibility to diphtheria In the United Kingdom unimmunized children under twelve will usually be susceptible to diphtheria and are unlikely to suffer from severe reactions to the vaccines. No test for susceptibility is therefore necessary for them. For adults and children over twelve, however, the following considerations apply: (a) Owing to the great reduction in the incidence of diphtheria in the United Kingdom, acquirement of natural immunity as a result of sub-clinical or mild infection is now unlikely. Such a natural immunity is, however, a possibility in individuals over twelve years of age and these persons do not need vaccination. A proportion of them would suffer more or less severe local or general reactions if vaccinated. (b) Conversely, individuals who have been immunized in early childhood, but who have not been given maintenance doses, will show an increasing tendency for their immunity to wane as adult life approaches. Hence from twelve years old onwards a test of susceptibility should be carried out before vaccination against diphtheria. Susceptibility test 91 The Schick Test (a) This is a biological test to determine whether a person has already developed his — or her own diphtheria antitoxin and is therefore no longer susceptible to the disease. (b) The test consists of the intradermal injection of Schick toxin. This is a toxic filtrate of a culture of Corynebacterium diphtheriae diluted with a buffer solution. The dose is 0:2 ml. and the strength of the diluted toxin such that this amount is rendered ineffective by mixing with 1/750 unit of antitoxin, but still causes a reaction when mixed with 1/1250 unit, if such mixtures are tested in the skin of a guinea-pig. In man, the average amount of antitoxin in the blood to neutralize the test dose is 1/200 unit per ml. (c) Since certain individuals may react to constituents of the test fluid other than the toxin, a control test is also made by injecting, at a different site, a similar dose of the fluid which has been treated by heat to destroy the toxin in it. 92 Technique The skin of the middle of the flexor surface of both forearms is cleaned with spirit and allowed to dry. 0-2 ml. of toxin is then injected intradermally, as described in para 62, into the cleansed site on the left arm and 0-2 ml. of control fluid is injected