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51
diphtaeroides and the bacillus Klebs-Loeffleri in the
latter (No. 2) and the bacillus Hofmanni in the former
(No. 1).
The peculiar localisation of these cases appears to
point to a sort of contact infection between distributor
and consumer, or what may be termed a limited milk can
or milk pail infection as opposed to a general milk supply
infection, when the localisation is more general, following
practically the milk carts. These specially localised cases
cannot be satisfactorily explained on the theory of farm
infection alone, but can on that of farm infection as
modified by contact infection (can or pail). Diphtheriainfected
farm milk was sent to the dairy X, and distributed
therefrom over wide areas, giving rise to cases
of diphtheria in many different districts, but more or less
sporadic cases, amongst the consumers of the milk.
Amongst the consumers were the milk distributors, some
of whom, in their turns, appear to have caused crops of
cases in specially localised centres (special roads) by
contact infection or milk can or milk pail infection, almost
house to house infection, through distributors who were
"carriers." It is somewhat difficult to allocate exactly
and definitely the parts played by these two separate and
distinct infecting agents.
The farm infection closed with the pasteurising of
the milk, and the "carrier" infection with the stopping
of the distributors from work, but, as the pasteurising of
the milk was commenced on a date prior to the suspected
distributors being definitely proved to be "carriers" and
consequently stopped from work, these two preventive
measures overlapped in their beneficial effects. A few
cases, however, might be exnected to occur after pasteurisation
from the "carrier" infection, which, if present,
would have continued during the time that elapsed
between the pasteurisation of the milk being commenced
and the distributors' work being stopped. On
theoretical grounds this should be so, and a few of the
late cases notified can, perhaps, be satisfactorily accounted
for on that assumption. Pasteurisation appears
to have overshadowed in its beneficial effects the beneficial
effects that might have resulted from the stopping
of the puspected distributors' work.