174 Arthropods as Direct Inoculators of Disease Germs 
precautions to prevent the ingress of rats. Cargo must be inspected 
just before being brought on board, in order to insure its freedom from 
rats. Even lines and hawsers must be protected by large metal discs 
or funnels, for rats readily run along a rope to reach the ship. Once 
infested, the ship must be thoroughly fumigated, not only to avoid 
carrying the disease to other ports but to obviate an outbreak on 
board. 
When an epidemic begins, rats must be destroyed by trapping 
and poisoning. Various so-called biological poisons have not proved 
practicable. Sources of food supply should be cut off by thorough 
cleaning up, by use of rat-proof garbage cans and similar measures. 
Hand in hand with these, must go the destruction of breeding places, 
and the rat-proofing of dwellings, stables, markets, warehouses, docks 
and sewers. All these measures are expensive, and a few years ago 
would have been thought wholly impossible to put into practice 
but now they are being enforced on a large scale in every fight against 
the disease. 
Rats and other rodents are regularly caught in the danger zone 
and examined for evidence of infection, for the sequence of the epi¬ 
zootic and of the human disease is now understood. In London, rats 
are regularly trapped and poisoned in the vicinity of the principal 
docks, to guard against the introduction of infected animals in ship¬ 
ping. During the past six years infected rats have been found 
yearly, thirteen having been found in 1912. In Seattle, Washington, 
seven infected rats were found along the water front in October, 1913, 
and infected ground squirrels are still being found in connection with 
the anti-plague measures in California, 
The procedure during an outbreak of the human plague was well 
illustrated by the fight in San Francisco. The city was districted, 
and captured rats, after being dipped in some fluid to destroy the fleas, 
were carefully tagged to indicate their source, and were sent to the 
laboratory for examination. If an infected rat was found, the officers 
in charge of the work in the district involved were immediately 
notified by telephone, and the infected building was subjected to a 
thorough fumigation. In addition, special attention was given to 
all the territory in the four contiguous blocks. 
By measures such as these, this dread scourge of the human race 
is being brought under control. Incidentally, the enormous losses 
due to the direct ravages of rats are being obviated and this alone 
would justify the expenditure many times over of the money and 
labor involved in the anti-rat measures. 
