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7
in his district, for his milk must have been infected about the 14th. Farm W had been visited by
the Medical Officer of Ilealth employed by the company, but no case of human illness was found there.
Turning now to the milk from X. This milk and this alone was supplied to all the vendors
known on June 20th to be implicated. Moreover, in the districts of A, B, C, D and E, where the
cases of scarlet fever occurred early in the outbreak (June 9th or 10th onwards), milk from farm X
was consigned between June 7th and 10th, while in those districts where the cases were later in
appearance (June 15th and onwards) the consignments were later, on the 14th or 15th. Again on
June 14th the whole of the milk from farm X went from the depot unpasteurised. On no other day
did this occur, and, judging by the number of attacks of illness immediately subsequent to it, this
was the day on which the milk did most mischief.
It should be noted that as regards vendor F we supposed on June 20th that milk despatched
from farm X on June 6th and distributed on June 7th had caused the attack in his district. In the
light of later knowledge we are disposed to think it possible, having regard to the date of commencement
of illness of cases in his district, and to other circumstances to be referred to later, that the
mischief, so far as he was concerned, may have been caused by some of the mixed (so-called
" pasteurised ") milk received by him at a later date, say on June 9th. (See also circumstances of A's
supply, page 8.)
Disregarding for the moment the particular case of the vendor F, the above-named facts constituted
in brief the evidence available on June 20th as a result of analysing the farm supplies.
Soon afterwards the circumstances of two other districts, J and K (see Chart I.), in which infected
milk had caused mischief, came to our knowledge, and in those two cases it transpired that milk from
farm X had been distributed just prior to the two outbreaks. The case of district J was especially
conclusive, inasmuch as this vendor received milk from farm X and from no other of the 31
farms supplying the implicated depot. In the case of L, a number of whose customers were attacked
comparatively late in the outbreak, there is no record of milk from farm X having been supplied. It
will be seen, however, from the chart that L received "pasteurised" milk, and therefore possibly
milk from farm X that was incompletely sterilised, on each day from June 15th onwards.
Distribution of milk from farm X.
It was now deemed desirable, with a view to learning more precisely how matters stood as
regards milk of farm X, and particularly to ascertaining when it became and how long it remained
infective, to study in further detail the distribution of the milk from this fiirm (so far as this could be
ascertained) and to compare this distribution with the dates of onset of symptoms in the several
affected districts. In the books kept by the manager of the company it was recorded that this milk
was distributed to various vendors as follows. The vendors whose customers were attacked are
lettered as before, and with them are included J, K and L, vendors whose customers were also attacked
but concerning whom we had no knowledge at the time when our analysis of the vendors' supplies
was in the first instance made.
Record of the distribution of the milk from farm X, on successive days, May 21st—June 19th.
Unless otherwise stated, the milk was unpasteurised:—
May 21st p.m.—Two vendors, none of whose customers were attacked.
,, 22nd a.m.—Separated.
p.m.—One vendor, none of whose customers were attacked.
,, 23rd a.m.—No record.
p.m.—" B," none of whose customers were attacked al>out this date, though they were later.
,, 24th a.m.—One vendor, none of whose customers were attacked.
p.m.—Pasteurised.
„ 25th a.m.—No record.
p.m.—Two vendors, none of whose customers were attacked.
,, 26th a.m.—No record.
p.m.—One vendor, " M "—No outbreak occurred among his customers.
,, 27th a.m.—Separated.
p.m.—"A," none of whose customers were attacked about this date, though they were later.
,, 23th a.m.—Separated.
p.m.—Pasteurised.
,, 29th a.m.—Pasteurised.
p.m.—One vendor, none of whose customers were attack ed.
„ 30th a.m.—No record.
p.m.—One vendor, none of whose customers were attacked.
„ 31st a.m.—No record.
p.m.—Two vendors, none of whose customers were attacked.
June 1st a.m.—Separated.
p.m.—Two vendors, none of whose customers were attacked.
,, 2nd a.m.—Two vendors (i.), none of whose customers were attacked about this date, though they were
later.
(ii.), none of whose customers were attacked.
p.m.—Two vendors (i.), none of whose customers were attacked about this date, though they were
later.
(ii.), none of whose customers were attacked.
,, 3rd a.m.—Separated.
p.m.—Two vendors, none of whose customers wore attacked.
,, 4th a.m.—Separated.
p.m.—"C," none of whose customers were attacked about this date, though they were later.
,, 5th a.m.—No record.
p.m.—One vendor, none of whose customers were attacked.
,, 6th a.m.—No record.
p.m.—" F —Cases occurred after the lapse of some days among "F's" customers, but apparently
X milk was not infective on the 6th. (See page 8.)
" G," none of whose customers were attacked about this date, though they were later.