s
is important to note, however, that the ships just mentioned, after calling at
Salina Cruz, enter upon a coasting voyage as far down as Coronel and return by
the same route, so that for the trans-Pacific voyage, Salina Cruz is really the port
of departure from the continent. The voyage from Valparaiso to Yokohama by
this route takes considerably more than two months. The ships do not call at
Guayaquil or at Tocopilla which are the only ports on the Pacific coast of the;
New World definitely reported as being indigenously affected, with yellow fever at:
present.
Î have not been able- to obtain details of the sailing ship lines engaged in
trans-Pacific trade, but the two charts which I append show the tracks followed
by sailing ships in-the Pacific Ocean, and- that information, is. sufficient for our
present purpose.
The chief conclusion to be drawn from the above summary is that at present
most of; the traffic-to the East starts from ports, such as Vancouver, and San
Francisco which are not now, and are not likely in the future to be, infected with;
yellow fever, but that there is also (and has been for some years) a moderate
amount of traffic from ports, especially on. the Mexican coast, which at least
must be regarded with suspicion.
Turning now to the new problems that will arise when the Panama Canal is
open for traffic, t may say at once that it is by no means sure that the canal will'
increase the risk of. the spread of yellow-fever to the extent that has been antici-
pated. In this connexion it must be noted that the yellow fever situation on the
Atlantic side of the canal and in the canal zone itself is now very diffèrent from
what it was in 1903 when Sir Patrick Manson first drew attention to
the dangers now under consideration. Since that time measures have been
taken which have gone fair to cause the disappearance of yellow fever-
from places which formerly were severely affected and to check ma--
terially the facilities for its dissemination from places where it is still
endemic. Very important facts are that Panama, Colon, Havana and other -
Cuban ports, New Orleans, Rio de Janeiro and nearly all the West India Islands-
are at present free from the disease, and that as regards such ports on the-
Atlant.ic side of the canal as are likely to be engaged, in trans-Pacific trade we
cannot name any that are definitely believed to be endemically affected at
present. in additon, great importance must be attached to the knowledge that
every possible precaution has already been taken, and will doubtless be continued,
to prevent the canal from being a route by which disease may be spread. It is
realised that the extensive use of the canal as a commercial highway would be
greatly affected by the failure of those precautions, and it is very improbable that
the United States will in the future neglect their great responsibility in regard to,
them. As conditions in the canal zone stand at present, a ship proceeding, say,
from New York to Honolulu, and calling only at Colon and Panama, would be as
safe from the danger of being infected with yellow fever as if she had not passed
through the endemic area at all. This being so it will be clear that, if the canal
attracts traffic which at present crosses Central America by one of the inter-
Oceanic railways and leaves from suspected ports on the Pacific coast, it may well
be a safeguard rather than a danger. It may happen, for example, that the
through traffic between New York and Honolulu and Japan, which at present
goes by way of Puerto Mexico and Salina Cruz, will in future be carried by
direct shipping through the canal and this would be a safer route. The shipping
from Salina Cruz to Tahiti and New Zealand may be affected in the same way.
On the other hand, of course, the increased "local" trade may add to "the-
present distribution of yellow fever and introduce new dangers which cannot at
present be foretold ; and it is clear also that we cannot be entirely without
apprehension regarding the possible risks from places like New Orleans- and other
ports in which several years' freedom from yellow fever has been followed by a.
cessation of vigorous anti-stegomyia measures, and that even as regards the
canal, its safety as a trade route depends upon the continuance of the present
very efficient arrangements in the zone and terminal ports.
This completes the summary so far as it relates to the degree of'danger at
the source of yellow fever and the risk that ships will start their voyages
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