H.—3l.

The 1924-25 epidemic commenced in Wellington, and its progress is shown in Table 4, in which are given the notifications, by weeks, for the different health districts as then constituted. It will be seen that the epidemic spread was more rapid in the North Island. In Central Wellington, where the epidemic broke out, the peak was reached by the middle of January, and the epidemic was rapidly declining in that area whilst still on the increase elsewhere. As will be seen later, the 1936-37 epidemic commenced in Dunedin at the beginning of December in so far as recognized cases were concerned, rose to a peak in the same month, and was declining there some considerable time before other districts were seriously affected. Of the two health districts contiguous to Wellington, the Taranaki-Horowhenua district, on the west coast, was much more seriously affected than the Wairarapa - East Cape district, on the east coast. The epidemic took some considerable time to cross Cook Strait to Canterbury, which suffered severely. In 1925 the disease had attained a strong hold on Wellington Province and was spreading elsewhere before restrictions on the movements of children were instituted. Every part of New Zealand was affected, but the southern portion of the South Island was not seriously so. The total notifications during 1924-25 were 1,252, and 195 deaths occurred. The age-grouping of the 1,159 cases occurring in 1925 was as shown below : —

Table 5.—Acute Poliomyelitis, 1925: Table showing Age-grouping of Cases.

There was another comparatively quiescent period from 1926 to 1932, in which latter year 150 cases were notified. Whilst the incidence of the disease was widespread, cases occurring in every district in the Dominion, the chief brunt of this outbreak was borne by the South Island (Canterbury 57 cases, Otago and Southland 37 cases). The 45 cases in 1933 were widely distributed, but one localized outbreak in Taranaki contributed 14 to the total. The incidence of the disease dropped markedly during the next three years, only 22 cases being notified between the end of 1933 and the Ist December, 1936. THE 1936-37 EPIDEMIC (Ist DECEMBER, 1936, TO 30th NOVEMBER, 1937). In New Zealand all actual or suspected cases must be notified, and all these cases are shown in the published weekly bulletin. All suspected cases so notified, and not subsequently confirmed, are omitted from the monthly returns of infectious disease, and therefore do not appear in the annual report of the Department. During the eleven months ended 30th November, 1936, 7 notifications were received from five districts, Nelson-Marlborough (January, November) ; Canterbury (February) ; Central Auckland (March, July) ; Otago (June) ; South Auckland (June). Of these, only 2 were confirmed' —the South Auckland case in June and the Nelson-Marlborough case in November. Assuming all these cases were poliomyelitis, the absence of confirmation being due to uncertainty of diagnosis in aparalytic cases, the year was one of exceptionally low incidence of the disease. Then at the beginning of December the condition very rapidly assumed epidemic proportions in Dunedin. That a mild form of poliomyelitis was prevalent in that area prior to December is indicated by the remarks of the Medical Officer of Health (Dr. T. Mackibbin), who in his report states : — " During October and early November, 1936, there was an unusual prevalence of pyrexia, gastro-intestinal disorders, and soreness of limbs. These febrile disturbances were not limited to the vicinity of Dunedin. For instance, in the Waikaka District, on the Otago-Southland border, there was at the same time as in Dunedin a wave of pyrexia and gastro-intestinal disorders. There was a similar wave in South Canterbury just before and while the first few cases were notified in Dunedin. A private school at Winchester was thus affected, and an early case in Oamaru was in a boy who had recently resided at the school. " Before it was known that paralysis was occurring these symptoms were not regarded as systemic signs of poliomyelitis, whereas later when it became known that this disease was epidemic all such cases were closely observed and on the first appearance of meningeal symptoms were hospitalized."

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Males. Females. Total. i I j Under 1 year .. .. .. .. 38 j 24 62 1 to 5 years .. .. .. .. 320 259 579 5 to 10 years .. .. .. .. 150 123 273 10 to 15 years .. .. .. .. 65 50 115 15 to 20 years .. .. .. .. 39 25 64 20 to 25 years .. .. .. .. 7 12 19 25 to 30 years .. .. .. .. 13 4 17 30 to 35 years .. .. .. .. 5 4 9 35 to 40 years .. .. .. .. 7 3 10 40 years and over .. .. .. 4 7 11 Totals .. .. .. 648 511 1,159