View report page

46
The cleanliness of the milk thus investigated is more or less satisfactory, but
obviously there is room for improvement. Cleaner methods of milk production
are being promoted by " clean milk competitions," fortunately more of these are
being held and the number of entries are inrceasing. The hygiene of milk premises
is being pulled up in accordance with powers given under the Milk and Dairies
Order, 1926. But at the same time there is much to be said in favour of a
suggestion that the Minister of Health should be asked to define a bacteriological
standard of cleanliness for ordinary (ungraded) milk.
Tubercle Bacilli in Milk.
Twenty-four samples of milk were examined for the presence of tubercle bacilli. Of these
five (20 per cent.), gave evidence of such infection.
The following are the brief paiticulars of the five infected samples :—
Sample I.—Purchased in the street from a roundsman. Sold as a designated
milk "pasteurised." Information was supplied by the vendors that the temperature and
period charts showed that pasteurisation had lieen properly carried out.
Animal inoculation gave the following results :—Guinea pig killed at end of three
weeks—normal. The guinea pig killed at the end of six weeks showed tubercles on both
liver and spleen and the presence of an e llarged gland of the mesentery.
Sample II.—Purchased from a retail dairy. Not sold as " pasteurised," although
there is good reason to believe that the milk was in fact pasteurised. Guinea pigs
inoculated with this milk were killed, one at the end of three weeks and the other at the
end of six weeks. Post-mortem examination showed the three-weeks guinea pig to be
normal. The six-weeks guinea pig showed an enlarged spleen with tubercles. Tubercles
were also present in the liver and enlarged glands were noted in the mesentery.
Sampi.f, III.—Purchased from a retail dairy. Not sold as " pasteurised " but probably
was in fact pasteurised. Post-mortem examination showed the three-weeks guinea pig to be
normal. The six-weeks animal showed a few tubercles on the liver and some enlargement
of mesenteric glands affording evidence of slight tuberculous infection.
Sample IV.—Purchased from a retail dairy. Served from a counter pan. Was not
sold as " pasteurised," but probably was in fact pasteurised.
On post-mortem examination the three weeks animal appeared normal. The six-weeks
animal showed a few tubercles in the liver; evidence of slight tuberculous infection was
thus afforded.
Sample V.—Purchased from a retail dairy. Not sold as " pastourised," but information
was given by the retailer that the milk was supplied to him as pasteurised. Post-mortem
examination of three-weeks animal showed enlarged spleen. The six-weeks guinea pig
showed tubercles on liver, spleen, mediastinal glands, peritoneal wall and mesentery,
evidence of tuberculous infection being thus afforded.
Information furnished by the vendors showed that the milk in Samples I, II, III and IV came
from the same wholesalers. No information could be obtained from them as to the farms from
which the milk came ; the milks were mixed milks derived from a very large number of farms.
The fifth sample wes a mixed milk obtained by the retailer from a firm of large wholesale
dealers. In this case information was sent to the Medical Officer of Health of the county in which
the wholesale depot is situated. Subsequently information was received from him that as a result
of enquiry about the method of pasteurisation employed it had been ascertained that in the winter
the milk was not heated at the usual temperature, 140° F. only being used with a "flash"
pasteuriser. The district Medical Officer of Health requested that in future the milk should be
brought to the proper heat for the correct time.
The County Medical Officer of Health also referred the matter to the Director of Agriculture
with a view to having the supplying herds inspected to discover the source of infection but as 90 herds
of cattle were involved it did not appear that the expenditure would be justified; arrangements
were to be made however for samples to be taken at the depot as the milk came in from the farms.