The Hawaiian star. [volume] (Honolulu [Oahu]) 1893-1912, 1909-01-08

ease prague is usually IaJdl III Jn6 rat
yet a number of cases of chronic
plague have been found in that ami.
NAL. In man, on the other hand,
plague has no chronic form. For these
reasons it is not to be expected that
we will find an infectious disease that
will sweep the rat out of existence. l
do not mean to say that the artificial
production of a fatal infectious dis
ease among rats is not a good thing,
but only wish to call attention to the
fact that determination is not to be
looked for from such measures. 1t
must be regarded as measure like the
use of poison. If plague, to which the
rat is markedly susceptible, has not
oxterminated the species there is lit
tie hope of finding a disease which
will.
Total destruction of the rat being
practically impossible, what prospect
is there of partial destruction. This
can be brought about in various ways
1t must not be forgotten that it is
rot a simple matter, such as picking
loose stones off a road. Every species
Of animals. in the long run, tends to
attain a numerical equilibrium in a
given region. This normal number of
individuals of a given species for a
given locality is determined by num-
Der of factors. prominent among
which is the food supply. This being
the case, if a given region will sup
port 1000 rats and we kill 500 of them,
in the case of such a prolific animal,
the normal number will be produced in
relatively short time. OF course if
we could kill the rats faster than they
could breed we would steadily reduce
the number as long as we keep up the
process. Experience teaches, however,
that this cannot be done. In Kobe the
Japanese killed almost 100000 rats in
the course of five years and at the end
Of that time the animals were as num-
erous as ever! A moderate killing of
rats only makes it easier for the re-
sidue to make a living.
One might reasonably reply that if
this is the case the whole game of rat
killing is not worth the candle and in
certain narrow sense this is true.
This is not true, however, in a wide
sense, particularly in Hawaii, and for
this reason. In endemic centers of
plague, such as Honolulu and Hilo,
every dead rat means a possible dead
nj rof 90
of the disease. For this reason alone
it is worth while to enumerate the
most efficacious means for killing rats,
bearing in mind that all means from
a blow with a half brick to the most
subtle poison are good if they kill
rats.
l. POISON. A large number of rats
can be destroyed in this way but the
campaign must be in responsible
hands and be carried out systemati-
cally. 1t is to be remembered that
much valuable information will be lost
if the dead animals are not collected
and examined by a competent bacte-
biologist to determine whether or not
they are infected with plague. This
applies also to all rats killed by any
means and particularly those found
dead. To make the examination OF
rats of real value the animals should
be tagged to show the locality where
they were found. If this is done and
plague rat is found it will be pos
sible to concentrate upon that place
and possibly prevent the formation of
a plague focus.
| do not go into the question of
merits of different sorts of rat poison.
This matter had best be left to those
in immediate charge of the work.
2. TRAPPING. This is particular
~ valuable as all the rats killed can
be examined. Trapping is more ex-
pensive than poison but is a good ac-
cessory.
g. ARTIFICIALLY INDUCED EPI-
DENIES. The widely advertised vir-
uses, of which Rattine and Danny's
Virus may be taken as samples, are
certainly able to kill a large number
of rats. The difficulty in their use in
Hawaii is that like many pathogenic
bacteria, the virus becomes inactive,
that is, unable to produce disease in
rats, If transported over great dis
tances unless means are taken to guard
the virus from all external influences.
such as heat, that will inactivate it.
1t must be remembered that these viz
uses are of the nature of poisons and
have the limitations of poisons Such
good accounts are given of these vir-
uses that it might be worth while to
attempt to get virulent culture here
in good condition, even if it required
special trip by a messenger.
T. CUTTING OFF OF FOOD SUP
. PLY. This is to be brought about by
, insisting upon the rat proofing of con.
, tainers of foods sought by rats The