CHAP. XI.] Measures to prevent the spread of infection by sea. 371
the regulations regarding the importation of merchandise, and this
important subject will be further discussed in Chapter XIV. The
measures to be taken on land frontiers have been noticed in the
discussion on land quarantine contained in Chapter X.
Measures to be
adopted at
ports of arrival.
Threefold
classification of
vessels.
The portion of the second chapter of the regulations which relates
to traffic by sea and the measures to be adopted at ports of arrival
is of great interest, not only because of its direct bearing on the con-
ditions of intercourse between India and Europe, but also because it
contains the conclusions of the Conference on the subject of the quar-
antine of vessels. The threefold division of vessels, referred to above,
is maintained in this chapter. Healthy vessels are those on board of
which there has been no case of plague; suspected vessels are those on
which, though cases of plague have occurred, no fresh case has occurred
within twelve days; and infected vessels are those on which plague has
been present within twelve days of the date of arrival. The period of
twelve days is calculated, as in the case of the seven days' period in
the Convention of 1892, by adding two days to the period of incu-
bation.
Infected vessels.
The regulations for infected vessels require the sick to be landed
and isolated, and the remainder of those on board to be subjected, at
the discretion of the local authority, either to " observation " or to
" surveillance " for a period which is not to exceed ten days from the
occurrence of the last case of plague. The term " observation " means
detention under observation either on board a ship or in a place of
segregation on shore. Persons subjected to " surveillance " are not
to be isolated, but are to be allowed to proceed at once to their desti-
nation where they are to remain under medical supervision. In the
case of an infected ship the dirty linen and other effects of the passen-
gers and crew which the local sanitary authorities may consider likely
to be contaminated, must be disinfected. So also must the parts of the
ship where the sick have resided, and the local authorities may require
a more extensive disinfection to be carried out. Lastly, the bilge-
water must be thrown out after disinfection and fresh drinking-
water supplied.
Suspected
vessels.
In the case of suspected vessels, a medical inspection and the
same process of disinfection, discharge of bilge-water and supply of
fresh drinking-water is prescribed. It is further recommended that
the crew and passengers should be subjected to "surveillance" for
a period of ten days from the date of arrival of the vessel.
Healthy vessels.
Pratique is to be given at once to healthy vessels, but it is also
provided that, at the option of the local authority, the precaution-
ary measures enforced in the case of suspected ships, except the disin-
fection of the vessel may be required; and it is also recommended