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38
A full account of the outbreak of diphtheria was given in the
Annual Report of 1932, and it is unnecessary to give the details of
its origin. It will be recalled that in the autumn of 1932, and the
spring of 1933, we experienced an outbreak of diphtheria of a particularly
virulent character. The records of the incidence of the disease
in Acton since 1890 show that there have been irregular periods of
maximum and minimum prevalence of the disease. Prior to 1932,
the last period of maximum prevalence had been in 1921, 1922 and
1923, and this followed a short period of only four years of minimum
prevalence. Between 1923 and 1932 the district had been
comparatively free of the disease. We therefore had a favourable
soil for the introduction of a virulent organism in a gradual accumulation
of susceptible persons in the population. Until September
1932, the disease followed a fairly normal course. Its incidence was
slightly higher than that observed in inter-epidemic years, but
there were no cases of extreme virulence in the early part of the
year. The virulent cases occurred at the end of September and beginning
of October, 5 cases occurring in different classes in one week,
3 of which proved fatal. These cases occurred not in an infants'
department, but in a junior department, and the next cases
occurred in a Secondary School. Formerly our deaths had usually
occurred in young chilren, either in those under school age or in
the infants' department.
Dr. O'Brien of the Wellcome Research Laboratory kindly
examined some swabs from the severe cases, and of 10 swabs examined,
6 were of the gravis type, 2 of the mitis type and 2 contained
bacilli of both the gravis and mitis types. We therefore had two
of the conditions which would conduce to the occurrence of severe
symptoms—a probable herd susceptibility and the presence of
virulent organism. The following table gives the number of notifications
and deaths, and it is given because it throws a light on the
probable effect of immunization on the course of the disease
Date. Notifications. Deaths.
1932 September. 17 3
October 33 4
November 48 9
December 17 2
1933 January 29 3
February 17 7
March 26 4
April 15 3
May 19 2
June 17 2