H.—3l.

INCIDENCE. Table 11.—Showing, by Race and Sex, the Population in each Age-group, the Number of Paralytic Cases of Poliomyelitis, and the Rate per 10,000 of such Cases in each Group.

It will be seen that, for Europeans in all age-groups, except one year and five to nine years, the male rate exceeded the female rate, and that for Maoris the male rate was in excess in all but three of the age-groups. The heaviest incidence fell on the two- and three-year-old groups. The attack-rate for the various age-groups differed markedly in the recent epidemic from the experience in the two major epidemics of 1916 and 1925. Whereas in 1924-25 the rate for children under five was 51-1 per 10,000 and for those from five to ten years was 21-9-—less than half that in the younger age-group —in 1936-37 the position was reversed, the heaviest incidence falling in the older age-group. The following table shows for the five-yearly age-groups under twenty years of age and for one group twenty years of age and over the incidence of all notified cases whether paralytic or not: {a) In the Wellington District, 1916 (337 cases which occurred during the first four months of the year), (b) in New Zealand for the period 1924-25, and (c) in New Zealand for the recent epidemic, and (d) the incidence of paralytic cases in each age-group during the recent epidemic. The latter shows that the incidence of paralytic cases was greatest in the lowest age-group.

Table 12. —Showing Incidence of Poliomyelitis, by Age-groups, in Three Major Epidemics.

92

Males. Females. Persons. Age-group. Rate Pn , Q Rate Rate f ' Cases. per ' Cases. per Population. Cases. per tl0n - 10,000. tl0n - 10,000. 10,000. Europeans. Under 1 year .. .. 12,200 6 4-9 11,900 3 2-5 24,100 9 3-7 1 year .. .. .. 11,600 7 6-0 11,100 13 11-7 22,700 20 8-8 2 years .. .. .. 11,800 31 26-3 11,200 23 20-5 23,000 54 23-5 3 years .. .. .. 11,800 31 26-3 11,300 26 23-0 23,100 57 24-7 4 years .. .. .. 12,100 25 20-7 11,500 20 17-4 23,600 45 19-1 Under 5 years .. .. 59,500 100 16-8 57,000 85 15-0 116,500 185 15-9 5-9 years .. .. 65,100 88 13-5 62,100 96 15-5 127,200 184 14-5 10-14 years .. .. 68,700 66 9-6 65,600 50 7-6 134,300 116 8-6 15-19 years .. .. 67,800 32 4-7 65,100 25 3-8 132,900 57 4-3 20-24 years .. .. 68,100 21 3-1 66,000 11 1-7 134,100 32 2-4 25 years and over .. 432,911 22 0-5 424,826 14 0-3 857,737 36 0-4 All ages .. .. 762,111 329 4-3 740,626 281 3-8 1,502,737 610 4-1 Maoris. Under 1 year .. .. 1,650 2 12-1 1,700 1 5-9 3,350 3 9-0 1 year .. .. .. 1,300 2 15-4 1,250 .. .. 2,550 2 7-8 2 years., .. .. 1,350 4 29-6 1,200 2 16-7 2,550 6 23-5 3 years.. .. .. 1,500 5 33-3 1,400 2 14-3 2,900 7 24-1 4 years.. .. .. 1,450 2 13-8 1,450 .. .. 2,900 2 6-9 Under 5 years .. .. 7,250 15 20-7 7,000 5 7-1 14,250 20 14-0 5-9 years .. .. 6,650 2 3-0 6,500 9 13-8 13,150 11 8-4 10-14 years .. .. 5,400 2 3-7 5,200 .. .. 10,600 2 1-9 15-19 years .. .. 4,300 1 2-3 4,050 1 2-5 8,350 2 2-4 20-24 years .. .. 4,000 3 7-5 3,850 3 7-8 7,850 6 7-6 25 years and over .. 16,300 3 1-8 13,974 2 1-4 30,274 5 1-7 All ages .. .. 43,900 26 5-9 405,574 20 4-9 84,474 46 5-4

(a) (b) (c) (d) 1916. 1924-25. 1936-37. 1936-37. Under 5 years .. .. .. 43-1 51*1 18-7 15-7 5-10 years .. .. .. 15-8 21-9 20-7 13-9 10-15 years .. .. .. 7-6 8-9 12-2 8-1 15-20 years .. .. .. 4-8 5-3 5-6 4-2 20 years and over .. .. 1-2 0-8 1-0 0-8