WASSERMANN REACTION. The Wassermann, or, per haps more correctly, the Bordet-Wassermann test of the blood serum and of the spinal fluid for active syphilis was elaborated in 1906 by Wassermann, Neisser and Bruck. It depends on the fact well-known to bacteriologists that foreign organic substances, e.g., disease germs in the body, stimulate the formation of compounds (which appear in the blood) designed to destroy the foreign or ganic substances or germs (see IMMUNITY). These anti-bodies effect their purpose with the aid of a substance present in prac tically all blood sera and known as complement. Bordet and Gengou, by devising a simple test for complement, showed that, in the process, complement was put out of action.
Wassermann, Neisser and Bruck adapted the Bordet-Gengou phenomenon to the purpose of detecting anti-syphilitic substance in the blood serum. They found that, in a mixture of (a) extract of liver of an infant dead of syphilis (which they regarded as ex tract of the germs of syphilis—Spirochaeta pallida—with which the liver was stuffed), (b) fresh serum of a guinea-pig—comple ment—, and (c) serum (previously heated to destroy its natural complement) of a syphilitic person, the complement was put out of action, and that this did not occur when serum of a normal person was substituted for that of a syphilitic. Thus they demon strated, as they thought, anti-spirochaeta-pallida substance in the blood of the syphilitic person and inferred from this that a similar phenomenon in any serum would prove syphilitic infection.
Later discoveries showed that extract of such an organ as nor mal heart of any animal would serve in the test as well as syphilitic liver, and it is now believed that the test does not discover anti spirochaeta-pallida substances, but anti-bodies to tissue cells which have degenerated in consequence of the action of Sp. pallida and act as foreign organic substances. The reliability of the test can best be described in the words of a committee of the Medical Research Council as follows : There is no process of biochemical diagnosis that gives more trust worthy information or is liable to a smaller margin of error than the Wassermann test when it is performed with completeness and with proper skill and care.
The percentages of cases of syphilis which give positive re actions to the Wassermann test vary with different pathologists, who have modified the original technique considerably—in the preparation of the extract, the proportions of the different re agents to one another and the periods during which they are allowed to interact, but broadly the reaction is negative for the first fortnight after appearance of the primary syphilitic lesion, and is positive in almost I 00 per cent of cases by the end of a month or six weeks. In older cases with outward signs of active syphilis the percentage is almost as high, but in those with no obvious signs (latent syphilis) it is rather lower. Treatment in the early stages usually converts the reaction to negative in a few weeks, but in later stages a persistently positive reaction is very common. A negative reaction does not prove cure or absence of the disease, and suspension of treatment when the reaction first disappears is commonly followed by relapse, a fact which the general public often does not realise. The reaction may be negative in the blood serum but positive in the spinal fluid, and vice versa.