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51
Of the 42 samples taken in September, one, or 2.4 per cent. were found to be infected
with the tubercle bacillus. The following is a summary of Sir Frederick Andrewes' report:—
Dirt.—31 out of the 42 samples were clean—74 per cent. In the remainder there were some
blackish specks in the deposit on standing, returned as traces of dirt. No really dirty sample
was present.
Tubercle.—The specimens were allowed to stand in conical glasses for 24 hours in the ice
box. Guinea pigs were then inoculated subcutaneously in the thigh with 1 cc. of a mixture
of the deposit and the surface cream.
As is liable to happen in animal houses containing many animals, a number of these
guinea pigs developed B. Aertrycke infections, 13 in all. In no case is it suggested that these
infections were derived from the milk; many other animals not so injected, died also. The
question arises how far such accidental deaths vitiate the purpose of the experiments. Bovine
tuberculosis is a continuously progressive lesion which should be manifest on careful scrutiny
during, at latest, the second week after inoculation. The earliest of these accidental deaths
was seven days after inoculation (No. 41) and in this no sign of tuberculosis could be found,
but I have preferred to exclude this case as a frustrate experiment. The earlier of the remaining
twelve cases were in the second half of the second week; no tubercle bacilli and no
sign of tuberculosis could be found in any of them, and I have therefore felt justified in classing
them as negative from the point of view of tuberculosis.
One animal, killed 44 days after inoculation, was found to present advanced tuberculosis,
and the tubercle bacillus was successfully cultivated (No. 20). On the basis of 41 examinations
this gives a percentage of 2.4 tuberculous samples—a very satisfactory result. Even if all
animals dying accidentally during the second week were to be excluded, the proportion of
tuberculous samples would work out at only 2.8 per cent.
(Signed) F. W. ANDREWES.
St. Bartholomew's Hospital,
November 24th, 1925.
The particulars in connection with the one sample in which the tuberculosis bacillus
was found to be present, were forwarded to the Medical Officer of Health of the London
County Council but the information derived from the visit of their Veterinary Inspector was
not very satisfactory, inasmuch as it was not found possible to establish the fact that the
sample examined actually came from the farmer whose name was on the churn. This farmer
stated that no churn bearing the number in question was sent by him to London within a
month either side of the date on which the sample was taken. The District Veterinary
Inspector reported that he had made an ordinary routine examination of the animals at the
farm a fortnight before the sample had been collected and had found no trace of tuberculosis
among them. He further reported that he examined the animals and farm again, subsequently
to the discovery of tubercle in the sample of milk, and found them to be " in a very good and
healthy condition, and show no signs of any contagious disease."
The following summary sets out the number of samples which have been found to be
infected with the tubercle bacillus on each of the occasions when investigations similar to
that now referred to have been made :—
year Percentage showing Year Percentage showing
Tuberculous infectio i. " Tuberculous infection.
1904 .... 7-7 per cent. 1917 .... 4-2 per cent.
1905 .... 9 1 „ „ 1919 .... 14-8 „ „
1906 .... 8-0 „ „ (24-2 „ „ 1st Series.
1907 .... 8-3 „ „ 1921 .... 1 26-3 „ „ 2nd
innQ ) 12*5 „ 1st Series. ( 12-5 „ „ 3rd „
lyuy -• | 4-7 „ ,, 2nd „ 1922 .... 9-5 „ „
1910 .... 6-25 „ ,, 1923 .... 2-6 „ „
1912 .... 6-6 „ „ 1924 .... 12-8 „ „
1913 .... 10-4 ,, ,, ]Q.-)r ( 2-4 „ ,, 1st Series.
1914 .... 10-2 „ „ -* | 2-4 „ „ 2nd „
1915 .... 8-5 „
The chemical examination, as in the first series, showed only one instance of adulteration
The vendor was cautioned and a subsequent sample taken was found to be satisfactory
The samples taken were sent from farms situate in the following counties :—
Essex 30
Suffolk 26
Norfolk .... .... .... .... .... .... .... .... .... .... 22
Hertfordshire .... .... .... .... .... .... .... .... .... 2
Cambridgeshire . .. .... .... .... . .... .... 4