TRAN SACT IONS. THE
ENGLISH
AS
DISSEMINATOR
BLACK OF
RAT
DISEASE.
BY DR. MARK R . TAYLOR, M . R . C . S . , etc.,
Southampton Regional Medical Officer of Health. THE Black Rat (Epimys Rattus, L.) is often spoken of as a relic of the past, with regrets for its disappearance. But the animal not only still survives in England : it is holding its own, in some places gaining predominance over its competitor, the Brown Rat (Epimys Norvegicus, Bork.), and all seaports can produce specimens. In fact it has never entirely disappeared from such favourable surroundings as our docks and warehouses, wherein its numbers are recruited by fresh arrivals on shipboard. Somewhere in the thirteenth Century an incursion of these rodents spread over Europe, as migrants from central Asia. In England there was no Rat at that time, so the new-comers rapidly increased and populated the land, for everything was in their favour : they were a race that lived with man and on man, and the man of that period furnished them with the most suitable lodgings. English folk in mediaeval times were habituated to such surroundings of filth and general uncleanliness that our imagination is stretched to realize how they did exist at all. T h e majority of the upper classes dwelt in wooden houses, with most primitive systems of sanitation ; the lower sheltered in hovels, mainly mud-walled, with no light, no Ventilation beyond a hole in the roof to liberate the smoke, a kennel or garbage-heap outside the door, and no sanitation whatever. Hence every house, whether °f rieh man or poor, became a Rat-run. If these animals acted as seavengers to some extent and so did their good deed a day, they were also the disseminators of disease : for Black Rats are intested by five different species of Fleas which can convey the virus of Plague. T h e cycle is thus : a Flea bites an infected heing, man or rat, so that the victim becomes infected and dies, i ne Fleas on him leave the corpse when it becomes cold, as is the custom of all Pulicidse, and find fresh victims to bite. 'ortunately the species of these Fleas, that has much the greatest power of conveying Plague, is by far the rarest; so that Plague