On this day in 1665, Pepys wrote in his diary:

“Great fears of the Sickeness [Plague] here in the City … . God preserve us all”.

He had earlier written with mounting dread of the advance of the disease across Europe, and of  the vain attempts to stem it by the quarantining of  incoming ships; and would later write  of its devastating spread, and, with heartfelt relief,   of its ultimate departure  in October, 1665.  Incidentally, it is commonly thought that the Plague was only killed off by the Great Fire of September, 1666, but the Worshipful Company of Parish Clerks’ “Bills of Mortality” confirm Pepys’s observation   that it died out at the beginning of the winter of 1665.

The 1665 outbreak of Bubonic Plague – the “Great Plague” – killed at least 70000 people in London, and possibly as many as 100000 – far more than the “Black Death” of 1348-9, although far fewer in proportion to the overall population.  The “Bills of Mortality” show that of the 70000 recorded Plague deaths, only 10000 were in the 97 parishes within the walls of the City  – possibly because a significant proportion  of those inhabitants who could afford to do so had fled to the country.  The remaining 60000  Plague deaths were in the 16 parishes without the walls, the 5 in Westminster, and the 12 in Middlesex and Surrey.  Stepney was the worst affected, with 6500 deaths.

Bubonic Plague was diagnosed by exquisitely painful swellings or buboes in the lymph glands in the neck, armpit and groin.  It was known to lead to death in most cases, generally in a matter of days or even hours, there being no effective treatment or cure for it.  It is now known to be caused by the bacterium Yersinia pestis, in turn generally transmitted by the bite of an infected  rat-flea of the species Xenopsylla cheopis  (such as was common in the conditions in which people, livestock, pets and vermin  lived, cheek-by-jowl, in London in the Medieval to post-Medieval period).   In the Medieval to post-Medieval period, it was thought to be spread by cats and dogs, which were therefore rounded up and killed in large numbers (the resulting  reduction in predation ironically allowing rats to proliferate).  The 1348-9 outbreak, now referred to as the “Black Death”,  caused so many deaths in such a short time that epidemiologists suspect that it was a particularly deadly and infectious – possibly pneumonic or septicaemic – strain  of the disease,  capable of being passed directly from infected person to person without the involvement of the vector flea.  Perhaps significantly in this context, the “Black Death”  was able to continue to spread and even to spike over the winter of 1348-9, when the vector flea would have been inactive, as it is everywhere  today at temperatures of less than 10degC.