The Black Death

Three such pandemics have been recorded. The first, beginning in Arabia, reached Egypt in the year 542. It ravaged and perhaps even fatally weakened the Roman Empire of Justinian and moved on across Europe to England, where it was known as the Plague of Cadwalader’s Time, and Ireland, which it laid waste in 664. The second pandemic was that of the Black Death. One of its parting flourishes was the Great Plague of London in 1665; it seems to have died out in the seventeenth century. Finally came the pandemic which started in 1892 in Yunnan and reached Bombay in 1896. In India alone it is believed to have killed some six million people. It made a brief and mercifully unsuccessful foray into Suffolk in 1910, finding only a handful of victims. Quite recently it has made itself felt in the Azores and parts of South America. In many parts of the world it has still to run its course.

Though on present evidence it is impossible to be categoric about the origins of the medieval pandemic, recent investigations by the Russian archaeologist Chwolson near Lake Issyk-Koul in the district of Semiriechinsk in Central Asia show that there was an abnormally high death rate in 1338 and 1339. Nestorian memorial stones attribute the deaths to plague.^{34} Given the later course of the disease and the fact that this area is in the heart of one of the zones in which bubonic plague lies endemic, Dr Pollitzer, probably the leading authority on the subject, has concluded that this was almost certainly the cradle of the Black Death.^{35} From thence it spread out, eastwards into China, south to India and west to reach the Crimea some eight years later.

In this remote fastness, since recorded history, the bacillus Pasteurella pestis has lingered on, finding its home either in the bloodstream of an animal or the stomach of a flea. The flea normally favoured is Xenopsylla cheopsis, familiarly X. cheopsis, an insect which, in its turn, chooses ideally to reside in the hair of some rodent. One can only guess which rodent was most readily to be found near Lake Issyk-Koul in 1338 but the experience of later epidemics points to the tarbagan or Manchurian marmot, a beguiling squirrel-like creature much hunted for its skin. The jerboa and the suslik probably also played their part and, of course, the rat too, though the latter’s main role was not to come till the disease was on the move.

To disturb the tranquil and largely harmless existence of Pasteurella pestis something had to happen to make the rodents leave their homes. With them, inevitably, would travel their attendant fleas and, within the fleas, a cargo of deadly parasites. We are unlikely ever to know exactly what it was which caused this particular rodent migration. Such evidence as survives suggests that they were driven away by floods but, on other occasions, prolonged droughts have provided the necessary incentive or it could simply have been that an increase in the rodent population put too great a strain on the available supplies of food. At all events a massive exodus took place and it was above all Rattus rattus, the tough, nimble, by nature vagabond, black rat which made the move.

Without disputing the importance of the rat as a carrier of plague, Professor Jorge has suggested that its role, except in the earliest stages of an epidemic, is inessential, and that the lack of references to it in contemporary accounts of the Black Death indicates that the infection was mainly dependent on other means of transport.^{36} He believed that Pulex irritans, the flea which preys above all on human beings, was perfectly capable of carrying the plague direct from man to man without the intervention of an infected rat. Medically this is doubtful. There is no need to eliminate Pulex irritans altogether as an extra factor but its capacity to drink in sufficient plague bacilli from one person so as to be able to implant a fatal dose in the next has been much questioned. Colonel MacArthur has recorded that, in blood cultures made from fatal cases of bubonic plague, he found ‘bacilli so sparse that theoretically one could have fed twenty thousand fleas on such a case and yet have infected none.’^{37}

There is certainly no doubt that the rapid spread of bubonic plague was greatly helped by the presence of infected rats. Nor was there any shortage of rats. By the middle of the fourteenth century they abounded in Europe, probably having been imported originally in the boats of the returning Crusaders. Their role was unobtrusive and, since there is no particular reason why contemporaries should have commented on their activities, their absence from the chronicle casts no doubt on their existence. Dead rats no doubt littered the streets and houses but this would hardly have seemed worthy of attention at a time when dead human beings were so much more conspicuous.