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17
Anthrax
One case of anthrax was notified during the year and was confirmed bacteriologically.
The patient was a stevedore at a wharf handling hides, bonemeal and
such-like articles. The medical reports showed that satisfactory progress was made.
Meningococcal
infection
Prior to the war the attack rate of cerebro-spinal fever had fluctuated mainly
between 0.02 and 0.05 per 1,000. Not unexpectedly the rate rose during 1940-41
to 0.3 per 1,000, a similar rise being experienced by most of the combatant nations
incidental with military and industrial mobilisation. Subsequently the rate fell
rapidly. In 1949 the incidence was only 0.023 per 1,000, the rate being the lowest
since before the 1914-18 war.
As from 1st January, 1950, the notification regulations were amended to require
the notification of all " meningococcal infection " as a single entity. In 1951 there
were 108 such notifications giving an attack rate of 0.032 per thousand. There were
25 deaths of which 20 were under 5 years but owing to imperfect notification the case
fatality from this disease is less than would appear from this figure. Incidence is
greatest in infants, e.g., 63 of the total of 108 cases were infants under the age of
5 years and of these 40 were boys and 23 girls. The attack rates for males are
consistently higher than for females at all ages.
Dysentery
During 1951 London in common with the rest of the country experienced the
highest incidence of dysentery since the disease became notifiable, the total of 4,069
notifications representing a fourfold increase over that of 1950 which had itself been
higher than usual. Deaths rose only from 6 in 1950 to 9 in 1951, the disease being
almost entirely of the mild Sonne type. The increased incidence of the disease has
presented two features calling for special mention. The first, of particular importance
to London, is that this disease which previously showed its highest attack rates in
rural areas now has the higher incidence in urban areas. The second is
that in London as elsewhere the increased incidence was more marked in the 5-14
age group than in the 0-4 group. During the year this disease which has always
shown a special predilection for day nurseries became epidemic also in certain of the
infants' departments of day schools. There is scope for further investigation into
the dynamics of Sonne dysentery epidemics in order to elucidate the part played by
school and nursery outbreaks in the dissemination of infection in the general
population.
Diphtheria
The campaign to encourage immunisation against diphtheria began in 1941 and
the results have been very encouraging. The fall in incidence since that date has been
far in excess of any downward fluctuation observed in the previous fifty years.
In 1951 there were only 30 cases or 0.009 per thousand living at all ages compared
with a rate of 0.024 in 1950 ; 69 per cent. of the cases under the age of 15 were among
those who had never been immunised and having regard to the relative size of the
unimmunised population this means that the attack rate among them was nearly
5½ A times as great as among those who had at some time been immunised. The effects
of the immunisation campaign are illustrated by the diagram, on which the continuous
lines indicate the trend of the notification rates in the three age groups 0-4, 5-14,15+
and the broken line indicates the percentage not artificially immunised. Attention
is drawn to the fact that there was an immediate acceleration in the rate of decline
in incidence at ages under 15 years from 1942 onwards, but that this did not take place
in the rate for those over 15 years of age until 1947. It cannot be without significance
that in the early days of the immunisation campaign both infants and school children
were artificially protected, and that five years later a substantial number of those
immunised in the schools had passed into the over 15 age group with obvious results
on the curve of incidence in this age group. During 1951 the rates have continued
their rapid decline. The degree of immunisation at school ages has risen from
77 per cent. in 1950 to 82 per cent. in 1951.