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4.7
In a few cases the origin of the primary infection could be
traced, three separate cases being attributed to the patients having
visited cases in London. One patient worked in the receiving
room of a laundry at the time that the disease was prevalent in the
district. There were, however, many cases in whom the infecting
source could not be found, some occurring amongst children who had
not been out of the district. It is highly probable that there were,
during the last few months of 1930, and in the early part of 1931,
a great number of missed cases going about while infectious.
Out of the 66 eases notified, 17 were primary. In 3 of these
a source of infection was known, namely, a case in London. In the
remaining cases there was no known contact. There were 49
secondary cases. Of these, 5 were home contacts of a 1930 case,
and 39 of a 1931 case. In 5 instances the case was attributed to a
school infection. In addition, it was discovered that there had been
14 cases whose onset occurred in 1931 in whom the diagnosis was not
made while the patient was in an infectious state, and a further 4
eases who had been attacked in the latter part of 1930.
A large number of the missed cases were assumed to be chickenpox
and no medical attendant called in. Chickenpox is not now a
notifiable disease in this area. Had it been so, it is possible that
some few of these cases would have been detected. During a
period of three months, however, when it was notifiable, only one
notification was received from a parent. The other two sources
of information of the prevalence of the disease are the head teachers
of the schools and the medical practitioners. The information is
received from the school whether or not the disease is notifiable.
The only advantage therefore accruing from the notification of
ehickenpox is obtained if there is a sufficient medical staff to enable
all cases to be visited. This, however, would not eliminate entirely
the risk of missed cases as many other diagnoses are made of
the eruption, the commonest being food poisoning and weakness
following influenza.
Of all the cases attacked, only four had been previously
^aceinated, excluding those vaccinated some days after exposure.
These cases were all secondary to a home infection with opportunities
[or massive doses of infection. All had been vaccinated in infancy.
Their ages were 28, 29, 34 and 37.
The commonest day of eruption from the onset of the illness
was the sixth, accounting for one-third. In one-sixth of the cases
it was the fourth and a similar number on the seventh. In four
cases no history of a preceding illness could be obtained.
The commonest interval between the onset of the primary and
onset of the secondary case was 20 days, the shortest period being
and the longest 28 days. From the occurrence of the rash of