H.—3l

The most marked decreases were diphtheria (234) and puerperal fever following abortion or miscarriage (55). Tables and comments regarding certain of the more common infectious diseases are given below: —

(a) Scarlet Fever.

The year 1928 was the " peak " year of the last epidemic experienced. The number of notifications declined rapidly until 1934, and then began to rise. The figure for 1936 is the highest since 1931. During the early part of the present year (1937) the number of notifications, contrary to expectations, decreased, an effect which may have had some association with the restrictions imposed on children during the epidemic of poliomyelitis.

(b) Diphtheria.

The incidence of diphtheria has been low for the past five years, and the number of notifications (513) is the second lowest figure recorded since 1902, the earliest year for which records are available. Another interesting feature of the returns is the remarkably low incidence of the disease in the South Island. The present position cannot be expected to continue indefinitely. The Dominion is apparently experiencing the trough of an epidemic wane, and a rising tendency is to be expected within a short period of years. (c) Poliomyelitis. Although only the early stages of the recent epidemic came within the period under review preliminary figures for the period December, 1936, to the end of June, 1937, are given below. These are subject to revision. A more detailed survey of the epidemic will be furnished in next annual report. On this occasion the epidemic commenced explosively in Dunedin in December, and declined in January and February, the cases with a few exceptions being confined to the southern portion of the South Island. In March cases began to appear more frequently in the North Island, and early in April the disease was widespread throughout the Dominion. The epidemic reached its peak in the latter part of April and then began to decline. Previous epidemics have always commenced in December or January, rapidly risen to a peak in February or March, and then declined. The abnormal course of the recent epidemic is probably due to the resistance offered to its spread by the restrictions imposed. Of the 819 cases reported during the seven months, 234 were of the " abortive " type —that is, the condition subsided without causing any apparent involvement of the motor cells of the central nervous system. Five hundred and eighty-five cases showed muscle weakness or paralysis of various groups of muscles. Many of these have completely recovered already, but it is too early to make any statement as to the numbers which will suffer from some permanent disablement. The incidence of reported cases in both the European and Maori populations was 0-52 per 1,000. The number of deaths reported totalled 39, a case fatality rate of 4-8 per cent, of all cases reported, or 6 per cent, of the cases showing paresis or paralysis. This rate is markedly lower than those recorded in 1916 and 1925, but as the epidemic has not yet completely subsided accurate comparisons cannot yet be made.

13

I Deaths. y Number of , Notifications. Rates per 10,000 of Case-fatality JNumDei. Mean p opulation- Rate per Cent . 1931 .. .. .. 1,304 11 0-08 0-84 1932 .. .. .. 829 6 0-04 0-72 1933 .. .. .. 783 4 0-03 0-51 1934 .. .. .. 762 8 0-05 1-05 1935 .. .. .. 863 8 0-05 0-93 1936 .. 1,152 8 0-05 0-69

Deaths. v Number of Notifications. Number Rates per 10,000 of Case-fatality Mean Population. Kate per Cent. 1932 .. .. .. 802 40 0-27 4-99 1933 .. .. .. 963 27 0-18 2-80 1934 .. .. .. 436 26 0-18 5-96 1935 .. .. .. 747 33 0-22 4-42 1936 .. .. .. 513 20 0-13 3-90