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POLIOMYELITIS IN AUCKLAND, 1947 49: AN EPIDEMIOLOGICAL STUDY (By A. W. S. Thompson, 0.8. E., M.8., M.R.C.P., D.P.H., Medical Officer of Health) FOREWORD In conjunction with its predecessor published last year, this report records an .attempt—perhaps the first of its kind—to trace the course of an epidemic of poliomyelitis in all its manifestations, subliminal and overt. The Auckland district was ideal for the purpose. It has now been recognized that very large scale studies involve so many doubtful factors of time and local circumstance that their epidemiological value is small. There is therefore a definite place for intensive field investigations of limited scope. The present inquiiy is concerned with a population of about 350,000, in which there were nearly 350 positive cases, and perhaps 100,000 cases never definitely diagnosed. In its concentration on these last lies the chief interest of this inquiry. A. W. S. Thompson, Auckland, 6th June, 1949. CONTENTS PAGE Foreword .. .. .. .. ' .. .. .. .. ..75 I. Introduction . . .. .. .. .. .. .. .. 76 11. Results of Previous Inquiry .. .. .. .. .. .. .. 76 111. Course of the Epidemic . . .. .. .. .. .. 76 IV. Incidence in Different Areas .. .. .. .. .. .. 77 V. Relationship Between Density and Incidence . . .. , .. .. 79 VI. Previous Epidemics and " Silent " Intervals .. .. .. .. 80 VII. Spread in the Auckland Urban Area .. .. .. .. .. 81 VIII. Severity at Different Ages .. .. . . .. .. .. .. 82 IX. Percentage Affected in Different Age Groups .. .. .. .. .. 83 X. Composition of Families of Positive Cases .. .. .. .. .. 84 XI. Incidence in Schools .. .. .. .. .. .. .. 85 XII. Discussion .. .. .. .. .. .. .. .. .. 87 Summary .. .. .. .. .. .. .. .. 89 Appendix (Tables VI to X) .. .. .. .. .. .. 90 Figures I. Course of the Epidemic .. .. .. .. .. .. .. 93 11. Incidence in Different Parts of District .. ... .. .. .. .. 94 111. Relationship Between Density and Incidence .. .. .. .. .. 95 IV. Auckland Urban Area : Positive Cases, 1942 to 1947 (July) .. .. .. .. 96 • V. Density and Incidence in Two Epidemics .. .. .. .. 97 VI. First Fifty Cases in Metropolitan Area .. .. .. . . .. ..98 VII. Second Fifty Cases .. .. .. .. .. .. .. .. 98 VIII. Third Fifty Cases .. .. .. .. .. .. .. ..99 IX. Cases No. 151 to 195 in Metropolitan Area .. .. .. .. .. 99 X. Severity in Various Age/Sex Groups .. .. .. .. .. .. 100 XI. Progress of the Epidemic in the Younger Age Groups .. .. .. .. 101 XII. Progress at Ages Ten to Fifteen Years .. .. .. .. .. .. 102 Tables I. Calculated Percentages of Age Groups Affected by Poliomyelitis, " Suspect" or Positive 84 11. Incidence in Schools Classified According to Standard of Sanitation Generally .. 86 111. Incidence in Schools : Scale of Ablution Facilities Provided .. .. 86 IV. Incidence in Schools : Scale of Closet Accommodation (Boys) .. .. .. 86 V. Incidence in Schools : Scale of Closet Accommodation (Girls) .. .. .. 86 Tables VI to X, relating to the figufes, will be found in the Appendix .. .. 90

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