PLAGUE.
Plague is an Eastern disease, which occasionally shows a tendency to become widely epidemic. It is due to a rod-shaped bacterium, averaging ·8 µ to 1·6 µ in length, which does not form spores. In its characteristic form patients suffering from this disease have inflammatary swellings (buboes) of various glands: hence the name Bubonic Plague. In other cases it simulates ordinary pneumonia, typhus or septicaemia; or the patient may be so slightly ill as to be able to walk about. It appears probable that the bacillus enters the body through cracks or other lesions of the skin, possibly also by inhaling infective dust. The rat is an important factor in the spread of plague. Very commonly plague has been widely prevalent and fatal among them before it attacks human beings. Rats also bring it in ships from infected ports. Hence one of the most important preventive measures is to kill all rats on board ship, before the cargo is unloaded. This has been done by sulphurous acid fumigation in the holds. The use of carbonic oxide gas will probably be found practicable for the same purpose. Manson has put the importance of this point tersely as follows: “To prevent cholera the tea-kettle, malaria the mosquito net, and plague the rat-trap.” Flies may carry the infection (page 281). It has been suggested that the fleas of rats carry the infection (page [281]).