SMALLPOX COWPOX.
Jenner was pleased to describe cowpox as a mild form of smallpox; but for what reason, outside his pleasure, he did not explain. Nevertheless the suggestion has borne fruit. When virus has fallen short, it has been asked, Why, if cowpox be mild smallpox, should not cows be inoculated with smallpox, and a crop of virus be raised? Various such attempts have been made, in which Mr. Badcock of Brighton has been especially distinguished. Mr. John Simon, writing in 1857, said, “Mr. Badcock, from 1840 to the present time, has again and again derived fresh stocks of vaccine lymph from cows artificially infected by him; having vaccinated with such lymph more than 14,000 persons, and having forwarded supplies of it to more than 400 medical practitioners.” When it is remembered that virus for half a dozen or more vaccinations is taken from a single arm, and that this process of reproduction is repeated every week, some idea may be formed of the extent to which this smallpox cowpox has been diffused over the country.
The original assertion that vaccination conferred life-long immunity from smallpox was unwillingly abandoned under stress of experience, until no respectable practitioner pretended that the rite afforded more than a partial or temporary security. In promotion of smallpox cowpox, however, Jenner’s most extravagant claims were revived. In Mr. Simon’s words, for the recipient of smallpox cowpox, “Neither renewed vaccination, nor inoculation with smallpox, nor the closest contact and co-habitation with smallpox patients, will occasion him to betray any remnant of susceptibility to infection.” Untrue even of variolation, it is unnecessary to controvert such a figment: it suffices to place it on record.
The hypothesis was, that smallpox inoculated on the cow lost somewhat of its virulence; but if so, why should not such cowpox inoculated on man resume its virulence? We are apt to forget that the nature of things is not controlled by our wishes, and that our interest in the conversion of smallpox into cowpox, and its maintenance as cowpox, is no warrant for fulfilment. I may also remark that though smallpox cowpox has entered so largely into currency, there is no evidence to what extent it has displaced the preceding issues of horsegrease cowpox, cowpox and horsepox. So far as we know, they are all existent in the common blood, indistinguishable, the stronger surviving, the weaker dying out: nobody knows, nor can know.