The pro-
in which the rats began to die was soon afterwards a plague infected building with its prisoners attacked by plague, and this occurred though the jail was exceedingly clean and in a good sanitary condi- tion. In houses also the mortality of rats prior to the occurrence of plague among the inmates was a frequent and notable fact. Indeed, the connection between the appearance of dead rats in a house, and the likelihood of the inhabitants being subsequently attacked by plague, became so thoroughly understood that often the more intelligent of the inhabitants gave notice to the Health Department immediately a dead rat was found on the premises in order that the department might take preventive measures. Dr. Weir, the Health Officer in his report on the plague in Bombay, says "as the epidemic proceeded people became alarmed in regard to the danger indicated by dead rats, and they com- menced to write to us in the following strain as this letter will show, 'As some dead rats were found in the house I am living in, and as I am afraid it is infected with plague, I want to vacate it temporarily and live in some sheds,' and the letter finishes with a request to occupy some municipal land." This intimate relation- ship between the mortality of rats and the propagation of plague was observed not only in Bombay, but in many parts of the Bombay Presidency.
bable modes of infection
from rat to rat have been experi- mentally
established.
Migration of rats was also observed. Healthy rats in an infected district seem to understand the danger to which they are subjected, and will move away from the locality. The rats' migration constitutes a danger to other districts. Dr. Weir observed this migration into a new district some time before sickness or mortality was noticed among the rats.
One of many examples is the following:-At a residence in a large garden on Bandra Hill, near Bombay, rats were seen in the house or garden till the 21st of January, 1897. About this time the garden and house were invaded with rats, and shortly after some of them died, others were killed by cats, and these became afterwards ill. Ten days after, one of the servants of the house, who had not been to Bombay for weeks, became ill and died of plague..
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7. The manner of infection from rat to rat has been experimen- tally shown to be produced by inoculating healthy rats with plagne bacilli, by smearing their nostrils with plague bacilli, by feeding them on food contaminated with plague bacilli, or on organs of a rat which has died of plague, and by keeping them in the same cages as sick or dead rats. There are in an infected house articles or objects soiled by plague patients or by sick rats to infect healthy rata. As soon as several rats are affected with plague it is only a matter of time before the disease assumes an epizootic form among them. This epizootic form of plague can only be stopped in its early stages by killing and afterwards destroying the rats.
The rat also appears to be more easily infected at times than In 1896 a man from Bombay, whose wife had died of
man.
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plague, brought her clothes home to his village, which had hitherto been quite free from plague. In a short time the rats in this man's house began to be sick and die, after which the inmates were attacked with plague and died, the man himself not being attacked until five of his relatives were affected.
279
man are not
8. The precise mode by which the rat infects man is not so clear The modes as the fact that it is an agent in propagating the disease. There of infection have been cases in which the sick rat has bitten man and plague from rat to has followed, but instances of this kind are rare.
There are so clear. other instances in which men engaged in removing rats dead of There are plague have been soon afterwards attacked with plague, while several ex- others in the same building not engaged in these operations have planations. remained free, indicating that the infection from the rats is not in the air.
Hankin records a case of this kind in a mill in which there were several thousand workmen. Rats were noticed to die in large numbers, 20 coolies were employed to remove the dead rats, out of the 20 no fewer than 12 were attacked by plague, while the rest of the workmen and others in the building remained healthy.
Simonds also records an example of rat infection in two women, caused by handling dead rats. The inhabitants of a village in the Punjaub were turned out of their village and placed in camp because of a commencing mortality among rats.
While in camp
two women were permitted to visit their home, and found on the floor of their house some dead rats; these they picked up and threw into the street, they returned to camp and a few days later they were attacked with plague,
Two explanations are advanced as to the method of infection. One is that the plague bacilli on the rat infects man through wounds or scratches on the hands or feet. The other is that the fleas which infest rats, and which have been found to contain plague bacilli, convey the infection to man, as well as to healthy rats. It has been observed that rate dead only a few hours are more dangerous than those which have been dead some time and- are quite cold, and it is surmised that this is because, in the recently dead rat the fleas are still on the body, while in a rat dead for more than a few hours all the parasites have left its body. It has been conjectured that fleas from dead rats may be the means of spreading plague to an adjoining house, even when the first infected house has been evacuated by its inhabitants, when steps have not been taken to dispose of any dead rate in the house, and proper measures of cleansing and disinfection are not undertaken. Without endorsing these views it is important to recognise their possibility and to leave no precaution untaken which may serve to lessen the spread of the disease by rats or diminish the risk of danger from them.
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. PUBLIC RECORD OFFICE
Reference :-
TILTIC.O.885
7
PUBLIC RECORD OFFICE, LONDON
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