The high prevalence of diphtheria in London during the past three years, 1920 to 1922, has surpassed all previous records, and for anything approaching it one must go back to the eight years' period between 1898 and 1901. It follows on a long spell of sixteen years' comparative freedom, from occurrence of the disease in epidemic form, during 1903 to 1918, when its incidence was with but trifling exception below the mean. The storm of infeetlon may be said to have arisen in the last half of t919, to have reached its height in the final quarter of 1921, and to have diminished but little in 1922. During 1918, the 8,173 cases notified exceeded the mean of 7,760 for the previous ten years, 1908 to 1917. The increase in notification in 1919 to 9,¢59 was concentrated in the last quarter of that year, and was succeeded by further rises, in 1920 to 13,780, in 1921 to 16,319, which unprecedented maxinmm was only slightly reduced in 1922 to 15,287. This abnormal prevalence has shown an annual rise in late autumn, with a corresponding fail in. early summer, and may therefore be described as a succession of waves, each crest higher than the last, each trough well above the ten years' mean. The general increase during this period, has, as might be expected, fallen heavily on our schools and is represented by the growing number of cases notified each year in the school-age period of 5-215 years. In z9z8, 414~6; r9x 9, 5293; z9zo, 6499 ; r92z, 9089 ; and in z9zz, 7352.* With the object of checking this heavy toll and for the prevention of further spread in the schools, special visits of investigation for diphtheria alone were paid to 317 elementary schools in 1920, During 1921 no fewer than 281 investigations took place in the schools situated in the 29 various metropolitan boroughs, but mainly, in the N.W.
