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9
pasteurisation of milk. Some outbreaks in other parts of the Country
have been caused by contaminated ice-cream, and the continued control
of the purity of this and other foods, is still of major importance in the
prevention of the spread of typhoid fever.
During 1950 one notification of Diphtheria was confirmed. The patient
recovered and investigation did not reveal the source of the infection. For
the ten years before the war, the average yearly numbers were 285 cases
and 8 deaths. This improvement is due almost entirely to the immunisation
of young children of whom upwards of 70% are immunised in this area.
One danger of immunisation must be kept in mind; this is that an
immunised and protected child may carry the infecting organism in the
throat or nose, and although the child itself suffers no ill effect, it can
infect and cause illness in other children; in other words, the child may
become a carrier. When only 50% of the children are immunised, the
number of carriers increases and the remaining 50% who are not protected
are consequently more likely to be exposed to infection and the number of
cases of diphtheria may be as many or even more than if none were
immunised. It is when the proportion of children immunised exceeds
60% that the real benefits of immunisation become apparent.
In this connection mention should be made of the undue publicity
given to the association between immunisation and poliomyelitis. It is
now known that during an epidemic of poliomyelitis, only a proportion
of the cases show any paralysis and a far larger number show no paralysis
at all. If during the incubation period a muscle is injured, then the group
of muscles in that area may become paralysed. In infancy the commonest
injury which is recorded is an injection for immunisation.
In Deptford during 1950 approximately 4,000 separate injections were
given throughout the year and paralysis of the arm where the injection
was given was found in 3 cases only, and in other parts of the country
proportion is probably of a similar order. Some of these cases would
have shown some paralysis in any case and although it has been established
that there is some connection between the giving of injections and the
onset of paralysis, there is no doubt, that the dangers have been greatly
exaggerated. Investigation is at present proceeding concerning the extent
to which these paralyses recover.
In the past the most effective vaccines for immunisation against
diphtheria had to be injected deeply into the muscle because they tended
to cause pain if they were injected close under the skin. With newer
preparations this disadvantage has been overcome and it is therefore
likely that the danger of paralysis due to immunisation during a poliomyelitis
epidemic will be avoided in the future. It has been advocated
that immunisation should be suspended during the poliomyelitis
“season.” In my opinion, this advice is not sound unless there is a severe
poliomyelitis epidemic in the district and unless one can be assured that
immunisation will be carried out when the epidemic is over. The danger
of a diphtheria epidemic following a fall in the proportion of children