THE PASTEUR TREATMENT The Pasteur treatment was first applied to human beings in 1885, after prolonged investigation and experimental trial on animals. It is based on the fact that the virus contained in the spinal cord of a rabid animal can be attenuated or intensified in the laboratory at will. By a system of graduated doses the resistance of the patient is raised until he can resist the strongest virus (see PASTEUR; IMMUNITY). For instance, the natural virus of dogs is always of the same strength; but when inoculated into monkeys it becomes weakened, and the process of attenuation can be carried on by passing the virus through a succession of monkeys until it loses the power of causing death. If this weak ened virus is then passed back through guinea-pigs, dogs, or rabbits it regains its former strength. Again, if it be passed through a succession of dogs it becomes intensified up to a maxi mum of strength which is called the virus fixe. Pasteur further discovered that the strength can be reduced by temperature and by keeping the dried tissues of a rabid animal containing the virus. The system of treatment consists in making an emulsion of the cord and graduating the strength of the dose by using a succession of cords, which have been kept for a progressively diminishing length of time. Those which have been kept for fourteen days are used as a starting-point, yielding virus of a minimum strength. They are followed by preparations of dimin ishing age and increasing strength, day by day, up to the maxi mum, which is three days old. These are successively injected subcutaneously. The original method has since been modified in details.
The first patient was treated by Pasteur's system in July 1885. Two forms of treatment are now used—(I) the "simple," in which the course from weak to strong virus is extended over nine days; (2) the "intensive," in which the maximum is reached in seven days. When the maximum—the third-day cord—is reached the injections are continued with fifth-, fourth-, and third day cords. The whole course is 15 days in the simple treatment and 21 in the intensive. The doses injected range from I to 3 cubic centimetres. Injections are made alternately into the right and left flanks.
Later treatment with an anti-rabic serum was suggested. Babes and Lepp and later Tizzoni and Centanni worked out a method of serum treatment, curative and protective. In this method not the rabic poison itself, as in the Pasteur treatment (active immunisation), but the protective substance formed is injected into the tissues (passive immunisation). At the end of 20 days' injections they found they could obtain so potent an anti-rabic serum (Babes using the dog, Centanni, the sheep) that even 1 part of serum to 25,00o of the body weight would protect an animal. This method of vaccination is useful as a protective to those in charge of kennels.
The efficacy of dog-muzzling in checking the spread of rabies and diminishing its prevalence has been repeatedly proved in various countries, but it was not applied systematically in England until 1897. Sometimes the regulations were in the hands of the Govern ment, and sometimes they were left to local authorities; in either case they were allowed to lapse as soon as rabies had died down. In April 1897 the Board of Agriculture determined to enforce muzzling over large areas in which the disease existed, and to maintain it for six months of ter the occurrence of the last case In spite of much opposition and criticism, this was resolutely carried out under Mr. Walter (afterwards Viscount) Long, the responsible minister, and met with great success. By the spring of 1899—that is, in two years—the disease had disappeared in Great Britain, except for one area in Wales; and, with this excep tion, muzzling was everywhere relaxed in Oct. 1899. It was taken off in Wales also in the following May, no case having occurred since Nov. 1899. Rabies was then pronounced extinct. During the summer of 1900, however, it reappeared in Wales, and several counties were again placed under the order. The year 190I was the third in succession in which no death from hydrophobia was registered in the United Kingdom. In the ten years preceding 1899, 104 deaths were registered, the death-rate reaching 3o in 1889 and averaging 29 annually. In 1902 two deaths from hydro phobia were registered. From that date the disease has been held in check in the United Kingdom.
See Annales de l'Institut Pasteur, from 1886; Journal of the Board of Agriculture, 1899; Makins, "Hydrophobia," in Treves's System of Surgery; Woodhead, "Rabies," in Allbutt's System of Medicine.