H—3l

The steady progress to saturation point of the male group aged 10-15 years contrasts sharply with the behaviour of the disease in girls of the same age. In their case a tendency to settle down about the 40-per-cent. mark was evident as early as May, 1948. In the pre-school groups there were more positive cases in males than in females (34 males, 21 females), but it is probable that the percentages affected by poliomyelitis in some form or another was identical. By the end of April, 1949, about one-third had been attacked. Amongst 5- to 10-year olds progress was remarkably steady throughout, especially in girls. The graph for female percentages begins at a lower level and ascends more steeply than that for males. In this age group I do not think that the apparent differences between them are illusory. The diagram for ages 15 and over has been omitted, being of little interest, By the end of April, 1949, 30 male cases and 19 female cases had occurred in these age groups. By then the calculated percentages affected amounted to 16 per cent, and 17 per cent, respectively. Throughout most of the epidemic the female percentage was higher than the male, but they ran together at the beginning of 1949. It is seldom appreciated that this age group comprises nearly 80 per cent, of the total population. They contributed only 22 per cent, of the positive cases in the Auckland urban area. To summarize, here are the calculated percentages of each age group which had been affected by poliomyelitis, whether " suspect " or positive, by the end of April, 1949:

Table I—Calculated Percentages of Age Groups Affected by Poliomyelitis, "Suspect" or Positive, by the End of April, 1949

X. COMPOSITION OF FAMILIES OF POSITIVE CASES Multiple cases were admitted to hospital from five families in the Auckland urban area and from six families living' elsewhere in the district. In each of these instances there were two cases, except for one family in a rural area which produced three. Several other instances came to notice in which undoubted clinical cases occuring amongst the family contacts of positive cases were not admitted to hospital and do not therefore appear in the published figures. In the earlier investigation forty households in which positive cases had occurred were observed over a period of about three months. During this time a second positive case occurred in four different houses and 43 per cent, of the remaining contacts had an illness which (for reasons explained in detail in the report) might be regarded as poliomyelitis in a mild form. Six seen during the attack were definitely diagnosable on clinical grounds, but were not admitted to hospital. It appears, therefore, that multiple family illnesses related to poliomyelitis must be far commoner than hospital returns alone would lead us to believe. Visiting the homes of positive cases in the early stages of the epidemic left one with two impressions about them: (a) that better-class homes appeared to predominate; (6) that these households included school-children more frequently than the average family.

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— Age 0-5. j Age 5-10. | Age 10-15. Age 15 and Over. Per Cent. Per Cent. Per Cent. Per Cent. Male .. 29 50 100 16 Female .. 38 61 44 17