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reflected in the smaller numbers and proportion of newly notified lung cases occurring
as fresh infections in children under five years of age (Table T3 page 32) and among
child contacts (Table T8, page 25). Sixty per cent. of all new notifications in 1954
were in the age group 15-44 years and 30 per cent. n persons over 45 years of age.
Since 1950 the proportion of persons over 45 among the new pulmonary notifications
has increased from 20 per cent. to 30 per cent., while new cases among those under
5 years of age have dropped from 5 per cent. of lung case notifications to 3 per cent.
Notification of non-pulmonary tuberculosis in children aged 5-14 years has shown
a steady fall in recent years (see Table T3 (ii) page 32). In 1947 there were 158 new
notifications ; in 1950 and 1954 there were 99 and 69 new cases respectively. This is a
gratifying fall in incidence and possibly justifies the expectations engendered by the
Milk (Special Designations) (Specified Areas) Order made in 1951 which forbade the
sale in London of unpasteurised or non-designated milks after October, 1951. Even in
this age group, a higher proportion of the non-pulmonary tuberculosis is due to human
infection than has hitherto been suspected. There is no doubt, however, that milk-borne
bovine type tuberculosis is now a comparative rarity. Table T5 (page 33) gives the
distribution according to site of non-pulmonarv lesions notified during the vear.
Further evidence of the lessened infective hazard among the general population is
seen in comparing the results of tuberculin surveys in various age-groups of London
children at different times.
Tuberculin
surveys
In 1929 some 20 per cent. of a tested group of five-year-old London children and
nearly 50 per cent. of thirteen-year-olds were found to be tuberculin positive, indicating
previous infection. In 1950 the figure among five-year-olds had fallen to 10 per cent,
and among thirteen-year-olds to 30 per cent. In 1954 tuberculin positive reactor rates
were 18 per cent. among thirteen-year-olds, with some evidence that among five-yearold
schoolchildren the rate was about 2 per cent.
London's tuberculous population
Currently, about 0.3 per cent. of those adult groups thought to be healthy and examined
by X-rays in London, are found to have active lung tuberculosis. If this figure is applied
to the whole adult population in the County, it would appear that there are about
8,000 undiscovered adult tuberculous persons in the community. Since mass X-ray
units tend to concentrate their examinations on those population groups thought
likely to contain a relatively high proportion of tuberculous cases, it may be more
realistic to reduce this figure by a half and estimate a likelihood of at least 4,000
undiagnosed pulmonary and probably 300 non-pulmonary cases in the County. If the
approximate figures of 32,000 known adult lung cases on clinic registers and 2,500
known non-pulmonary cases are added, an estimate is obtained of some 38,800 adult
(i.e., over 15 years of age) cases of tuberculosis in the London population.
It will be seen from Table T7 (page 35) that at the end of 1954, of the 34,473 lung
cases on the clinic registers, 18,897 were males and 15,576 females. One per cent. of
these lung patients known to the clinics were under 5 years of age; 6 per cent. were aged
5-14 years; 16 per cent. were aged 15-24 years; 51 per cent. were aged 25-44 years
and 26 per cent. were over 45 years of age. From these figures, kindly provided by the
clinic chest physicians, it is clear that among the population of London as a whole
0.2 per cent. of children under 5 years are known to have tuberculosis of the lung ;
0.5 per cent. of children age 5-14 years; 1.4 per cent. of persons aged 15-24 years ;
1.6 per cent. of persons aged 25-44 years and 0.7 per cent. of' over 45s'. The Diagram
(page 26) shows the numbers of known tuberculous persons per 1,000 of the population
in each age and sex group.
The chest clinic registers contain the names of 1.2 per cent. of all males in London
and 0.9 per cent. of all females. Not all these cases have active disease ; many have
responded well to treatment, are 'quiescent' or 'arrested' and are simply kept under
medical surveillance until it is felt safe to consider them recovered and very unlikely to
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