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Was called into question. The diagnosis of chicken pox was
subsequently and expeditiously confirmed by a report from
the Central Public Health Laboratory on the pathological
examination of material from a scraping from a scab.
Contacts of Smallpox — surveillance. Maintenance of
supervision over- contacts coming into the district had to be
carried out in two cases during the year. These were contacts
with a case of smallpox on the S.S. "Strathmore" which
arrived in Tilbury on the 12th February from Sydney via
Bombay. A girl aged 12 embarked at Bombay on the 26th
January and became ill on the 28th with suspected smallpox.
The contacts were kept under surveillance for the prescribed
16 days.
Scarlet Fever. There were 155 cases of Scarlet Fever
notified during the year, giving a case rate of 2.08 per thousand
population. 75 were nursed at home—48% of the total. The
disease was of mild type and reference has been made in the
section on Infectious Disease Hospitals on page 30 to the fact
that there seems to be diminution in the extent of admission to
hospital for this disease. 52% of cases only were so isolated,
the lowest percentage on record as a table reproduced in that
section shows.
110 of the cases were school children, 10 of these from
schools outside the district, 8 were adults and 37 in children
under school age.
Reference to the table on page 61 shows the ward distribution
of the incidence. It will be seen that over a quarter
of all the cases during the year came from the Morden Ward.
Various parts of the area from time to time seem to suffer the
heaviest incidence. In 1944, for example, 102 (or half of all
the cases) came from the St. Helier Ward. West Barnes Ward,
which had a total of only 7 cases in the three years 1945, 1946
and 1947, had 62 cases in the immediately preceding three years
1942, 1943 and 1944. There are probably several factors
operating to produce this result; the first and most important
is probably population structure. In the years when particular
wards are heavy contributors there is a high child proportion
in the population. The other important factor which is
probably playing an important part is herd immunity—the
level of protection of the group, and as the disease is for practical
purposes confined to children this means the level of
immunity which the children as a group have achieved. It will
be seen that a year or two of high incidence is generally followed
by a few years of. low incidence, the immunity level of the
group having been raised.
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