THE DISASTROUS MORTAL disease known as the Black Death spread across Europe in the years 1346-53. The frightening name, however, only came several centuries after its visitation (and was probably a mistranslation of the Latin word 'atra' meaning both 'terrible' and 'black)'. Chronicles and letters from the time describe the terror wrought by the illness. In Florence, the great Renaissance poet Petrarch was sure that they would not be believed: 'O happy posterity, who will not experience such abysmal woe and will look upon our testimony as a fable.' A Florentine chronicler relates that,
All the citizens did little else except to
carry dead bodies to be buried [...] At
every church they dug deep pits down
to the water-table; and thus those who
were poor who died dining the night
were bundled up quickly and thrown
into the pit. In the morning when a
large number of bodies were found in
the pit, they took some earth and
shovelled it down on top of them;
and later others were placed on top
of them and then another layer of
earth, just as one makes lasagne with
layers of pasta and cheese.
The accounts are remarkably similar. The chronicler Agnolo di Tura 'the Fat' relates from his Tuscan home town that
... in many places in Siena great pits
were dug and piled deep with the
multitude of dead [...] And there
were also those who were so sparsely
covered with earth that the dogs
dragged them forth and devoured
many bodies throughout the city.
The tragedy was extraordinary. In the course of just a few months, 60 per cent of Florence's population died from the plague, and probably the same proportion in Siena. In addition to the bald statistics, we come across profound personal tragedies: Petrarch lost to the Black Death his beloved Laura to whom he wrote his famous love poems; Di Tura tells us that 'I [...] buried my five children with my own hands'.
The Black Death was an epidemic of bubonic plague, a disease caused by the bacterium Yersinia pestis that circulates among wild rodents where they live in great numbers and density. Such an area is called a 'plague focus' or a 'plague reservoir'. Plague among humans arises when rodents in human habitation, normally black rats, become infected. The black rat, also called the 'house rat' and the 'ship rat', likes to live close to people, the very quality that makes it dangerous (in contrast, the brown or grey rat prefers to keep its distance in sewers and cellars). Normally, it takes ten to fourteen days before plague has killed off most of a contaminated rat colony, making it difficult for great numbers of fleas gathered on the remaining, but soon-dying, rats to find new hosts. After three days of fasting, hungry rat fleas turn on humans. From the bite site, the contagion drains to a lymph node that consequently swells to form a painful bubo, most often in the groin, on the thigh, in an armpit or on the neck. Hence the name bubonic plague. The infection takes three-five days to incubate in people before they fall ill, and another three-five days before, in 80 per cent of the eases, the victims die. Thus, from the introduction of plague contagion among rats in a human community it takes, on average, twenty-three days before the first person dies.
When, for instance, a stranger called Andrew Hogson died from plague on his arrival in Penrith in 1597, and the next plague case followed twenty-two days later, this corresponded to the first phase of the development of an epidemic of bubonic plague. And Hobson was, of course, not the only fugitive from a plague-stricken town or area arriving in various communities in the region with infective rat fleas in their clothing or luggage. This pattern of spread is called 'spread by leaps' or 'metastatic spread'. Thus, plague soon broke out in other urban and rural centres, from where the disease spread into the villages and townships of the surrounding districts by a similar process of leaps. …