View report page

42
Numerous types of the diphtheria germ are known to exist, but,
whilst all types are similar in microscopic appearance, only a few are
virulent to man. Even so, several grades of virulence are recognisable.
The danger from the germ in any particular case cannot however be
determined at the bedside, but by animal experiment requiring the
passage of many days. Luckily the prevailing type of diphtheria germ
in this country has in the past been of low or medium virulence.
The Risk of Infection.
At certain seasons the virulence of the diphtheria germ becomes
self-exalted. When this occurs the carrier-rate rises, leading in a few
days to a crop of cases among susceptibles. Conditions are then ripe for
an epidemic to occur.
Normally some 5% of healthy children attending school are
carriers of diphtheria. Children in the same class as a carrier naturally
acquire the germ by contact. If unprotected by inoculation they may
suffer the illness: if previously immunised they are likely merely to
become carriers also. In this way, the routine immunisation of school
children. whilst reducing the number of actual cases, tends indirectly
to inflate the number of carriers. Hence the paramount need for a
maximal effort in securing the immunisation of each school child.
The Position in Richmond.
In the Spring of 1945 an analysis was made of the state of
immunity of all Richmond school children, and a Report was issued to
the Council.
It was shown that the proportion of school children of the
Borough who had been subjected to inoculation against diphtheria
stood as high as 78%. This compared favourably with the corresponding
figures for most local authorities in Surrey, and extremely well
with the figure of 56% for England and Wales.
The Changing Outlook.
In the light of modern experience, our conception of diphtheria
as a disease has recently undergone a certain change. It has become
clear that inoculation, as practised with such resounding success in past
years, cannot fully protect a community against the diphtheria germ
when it appears in its most virulent form.