Page:Tropical Diseases.djvu/421

XXII] by some system of artificial immunization, devised such a system, and has practised it on a scale sufficiently extensive to warrant some conclusions.

During the Maidstone epidemic of typhoid in 1897, of 200 individuals, the subjects of special observation, 95 were inoculated, 105 were not inoculated. None of the former contracted typhoid, whereas 19 of the latter were attacked. Encouraged by these results, Wright proceeded to inoculate on a larger scale. In the British Medical Journalof January 20, 1900, he summarizes his results up to that date. Of 11,295 British soldiers in India, to whom his observations apply, 2,835 were inoculated, 8,460 remained uninoculated. Of the former, 27 at some subsequent time had attacks of naturally acquired typhoid; of the latter, 213 were similarly attacked; the percentages being 0.95 and 2.5 respectively. In these attacks 5 of the previously inoculated died; 23 of the uninoculated. On the assumption that the whole of the British army in India was inoculated and that the foregoing results were maintained, there would be an annual saving of over 1,000 cases of enteric and of nearly 200 lives. Since that time Sir A. Wright, with an industry and zeal in keeping with the important stake at issue, has steadily pursued his investigations. The English garrison in Egypt and the South African War afforded opportunities to test his conclusions in other fields, and on an extensive scale. The figures appear to justify the conclusion that these inoculations lead to at least a twofold reduction in the incidence of the disease in those inoculated, and a 50- per-cent. reduction of the case-mortality. Crombie concluded from a careful and independent examination of the statistics, based on the results of inoculation as against non-inoculation in a group of 250 officers invalided from various causes from the South African War, that up to the age of 30 the advantage of a single inoculation is distinct— 27 per cent, of the inoculated being attacked, as against 51 per cent, of the non-inoculated. Beyond 30 he found the positions reversed, the advantage being with