GOVERNMENTAL SERVICES 141 
Diseases which were formerly not considered sub- 
ject to it are today restricted by its use; and it is 
not unlikely that diseases which are not today 
recognized as spread by germs may later be 
stamped out by quarantine. 
106. Methods in Quarantine. Formerly quar- 
antine consisted simply in preventing the entrance 
of persons or animals upon infected premises, or 
their exit therefrom. Fences were erected around 
yellow fever premises, but the disease spread. 
Now effective quarantine is maintained by screen- 
ing in the patient, and killing the mosquitoes. 
After three days the yellow fever patient is no 
longer able to transmit the disease to the stego- 
myia mosquito, and further quarantine is useless. 
The malarial patient must be kept under guard 
sometimes for months. Rats, and the fleas which 
they carry, are the means by which the bubonic 
plague is spread. Quarantine in these cases there- 
fore means destruction of the vermin for a certain 
district, always working from the outside of a 
circle in whose centre infection has been found.** 
In veterinary practice a quarantine may mean 
only the restriction of certain kinds of animals, 
or the restriction of the passage of all members 
of the animal kingdom. For the Texas cattle 
fever quarantine includes killing the ticks, either 
by dipping the infected animals, or by destroy- 
ing the animals and disinfecting the premises. 
Infected animals may be useful for food purposes, 
so that burning the carcasses is not necessary, as 
it is for anthrax. Anthrax has been known to be 
28PusLic HeaurH, §§ 402, 
403. 
