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Poliomyelitis in Auckland, 1947–1949. An epidemiological study*

Published online by Cambridge University Press:  15 May 2009

A. W. S. Thompson
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(a) This paper is a study of a poliomyelitis epidemic in the Central Auckland Health District which commenced in November 1947, and by the end of April 1949 had produced 345 cases in a population of about 350,000.

(b) Incidence per 10,000 reached 8·0 in the city, 15·4 in the country districts, and 21·5 in certain urban areas lying between city and country.

(c) In general, incidence was inversely related to population density. Abnormally high incidences in some urban areas was attributed to influx of rural dwellers in recent years. Unusually low incidence in one city area may have been related to the periodic effect of race meetings in increasing the local density.

(d) The three previous Auckland epidemics showed a successively declining incidence, and were linked by periods of grumbling activity. The present epidemic was preceded by a lull, and its toll has approached that of the 1916 epidemic. It is probable that a new cycle has begun which will imitate the first, but on a lower scale.

(e) Spot maps showed that the disease was already widespread before the first positive cases revealed its presence. Some ebb and flow, but no actual movement from one area to another, occurred during its course. An interesting feature was the comparative rarity of cases in the neighbourhood of the city's sewage-polluted bathing beaches.

(f) An inverse correlation was noted between the ratios of ‘suspect’ to positive cases established in a previous inquiry, and the incidence of cases with paralysis or paresis in various age/sex groups. High ratios indicated lower severity.

(g) It was estimated that by the end of April 1949, all boys 10–15 years in Auckland had been affected by poliomyelitis, either ‘suspect’ or positive. Less than half the girls of this age had been affected. Estimates are given for the other age groups.

(h) Families of cases showed no significant difference in composition from the average in the area.

(i) No correlation, whether inverse or direct, was found between sanitary conditions in schools and the incidence of positive cases.

(j) The cycle of poliomyelitis in the community is discussed in the light of these findings.

Type
Research Article
Information
Journal of Hygiene , Volume 48 , Issue 1 , March 1950 , pp. 96 - 120
Copyright
Copyright © Cambridge University Press 1950

References

* ‘A Contribution to the Epidemiology of Poliomyelitis in New Zealand’. This Journal, 1948.

* Figures for age and sex composition of these populations are not available. Cases in each age group have therefore been related to the total population in each area. In other words, the graphs have been constructed as if the populations concerned were equally distributed between the eight age/sex groups. The principal effect is to exaggerate the importance of cases amongst ‘over 15's’.

In London in 1947. Sir Allen Daley B. Benjamin (1948), The Medical Officer, 80, 171.

† Figure 6 corresponds to Fig. 1 (1) in the previous paper. Some minor corrections have been necessary.

* This prediction proved correct. Notifications (whole district) in the succeeding five months were: 4, 4, 6, 3, 3; hardly an epidemic prevalence for a population of 350,000.

* I am aware, of course, that the latter is now regarded as being merely a sensitivity reaction to the lymph which can have no real equivalent in poliomyelitis. Nevertheless, a true reaction to the virus probably occurs also, even though it may not be the reaction which we see.