In the Dulwich Village graveyard lie the bodies of 35 of the 42 victims of the great plague of 1665. It has been estimated that approximately one in six of the population of Dulwich fell victim to this horrendous disease. The cause of plague then was entirely unknown, although in later years it was identified as due to a bacterial cause, namely Yersinia pestis, spread by fleas from rats.

Plague is a severe, transmissible and often fatal disease, until recently poorly understood, and without known cause or means of treatment. During the 5th century BC, plague was attributed to “the anger of the gods who in their wisdom had sent plague to punish mankind for its sins”. In another age in Venice, Jews were accused of poisoning the wells, this led to attempts at their expulsion. Many major epidemics occurred around the 14th century in overcrowded populations with poor sanitary conditions, foul sewers, and proximity of cattle, and were endemic from the Far East to the Mediterranean. Epidemics were common up to the 17th century, culminating in the severe epidemic of 1664 - 1665, after which it virtually disappeared without satisfactory explanation.

The illness was characterised by extensive body pains, terrible lassitude, and a high mortality. The development of painful swellings on the limbs (buboes) leading to a generalised and usually fatal illness are the added features of bubonic plague, a plague which may have killed approximately 20 million people during three years of the 14th century - hence the title of “the Black death” of 1347. Between one quarter and one third of Europe’s population may have died from the plague at that time.

Mankind has been prone to epidemics of different diseases throughout history. They may involve entire populations, are frequently fatal, often of unknown cause and without effective treatment. They tend to occur where there is overcrowding, dirt and poor sanitation. Characteristically, the disease spreads rapidly and widely in a particular area and for a limited period. An epidemic represents an outbreak of a disease over a limited period when a significantly greater number of persons in a community or region are affected. Thus, an epidemic represents a temporary increase in prevalence. Its extent and duration are determined by the interaction of such variables as the nature and infectivity of the causal agent, its mode of transmission, the degree of pre-existing and newly acquired immunity.

An epidemic can be caused by a great variety of diseases, some described here. A pandemic occurs when the illness spreads rapidly across the planet. A good example is the influenza epidemic after World War 1 which caused at least 20 million deaths. Epidemics of diseases such as smallpox and measles led to the collapse of the Incas and Aztecs, while typhus halted Napoleon’s expedition into Russia. Malaria may have been carried to the Caribbean and the Americas.

The high mortality during the many recurring epidemics of Cholera, worldwide, during much of the 19th century was of much concern. Major epidemics occurred in Britain in 1832, 1848 and 1854, the latter two occurring in London. The disease is characterised by diarrhoea leading to devastating intestinal loss of fluid and electrolytes carrying a very poor prognosis. Its cause was unknown, and the idea that it might be water borne was highly controversial and indeed vilified by the Lancet over many years. However, the experimental work of John Snow (1813-1858), who prevented access to contaminated water by removal of the Broad Street pump handle, left little doubt that water was the source of the epidemic. It is interesting to note that my own ancestor Robert Webb Watkins (1792 - 1844), surgeon apothecary in the small town of Towcester, made similar observations during the autumn of 1854 when cholera “visited for the first time the small town of Towcester with great severity”. It was described as “raging to a fearful extent spreading more to the wealthy whose houses were nearer to the river than the dwellings of those of the poor. No one then knew either cause, prevention or treatment. He reduced the incidence of cholera by rebuilding some of the brick sewers in the town. Latterly it was shown by Robert Koch (1883) that the offending cause of the disease was due to the bacterium Vibrio Cholera. Cholera now occurs predominantly in Latin America and Asia, and particularly in India. It occurs only in man and there is no animal reservoir.

Down the ages, Dulwich parents have naturally been anxious about diseases which might threaten their children. Among these was Smallpox, a viral infection and a major cause of mortality in England, with severe outbreaks (including Dulwich) in the 18th century. This has now been eradicated by vaccination. Similarly, Diphtheria, a bacterial infection affecting the upper respiratory tract, particularly in children, proved a “killer” in epidemics in the 18th and 19th centuries. Today this has largely been eliminated by immunisation.

Streptococcal bacterial infections were responsible for many of the illnesses including puerperal fever, throat and skin infections and sometimes might lead to rheumatic fever - in the last with possible cardiac damage. Again, these infections have been significantly reduced by antibiotic use.

More recently, Poliomyelitis, a viral infection, with faeco-oral spread, caused major epidemics, the last in the UK in 1947, 1950 and 1955. These might, in 1%-2% of cases, result in infantile paralysis, with a significant morbidity. Immunisation again has largely eliminated this scourge.

Robert Koch (1845-1910) at a presentation in Berlin in 1882 described the tuberculosis (TB) mycobacterium. TB (Consumption) has taken a vast toll of humanity, one in seven of all humans were dying from this cause in the 19th century. Sufferers rushed to Berlin - “the walking dead of Europe” having heard that the great scientist had discovered a new remedy. But he had not, and sufferers were dying everywhere - in their cars, their hotels and their hospitals. From his experiments, Koch drew a single but crucial conclusion, namely that the “germs” he had described were bacilli causing death through the disease of TB. It was not until 60 years after discovery of the causative organism that the first effective treatment - streptomycin - was discovered. The WHO has estimated that deaths from TB are likely to rise from the current 2.5 million a year, to 3.5 million by the end of the 21st century. However, infectious diseases such as cholera, diphtheria, polio and smallpox have greatly diminished as major causes of death following intensive immunisation programmes.

New epidemics will continue to threaten global health with a potentially high mortality. AIDS (Acquired Immune Deficiency Syndrome), Ebola, MERS (Middle East Respiratory Syndrome) and now the arthropod Zika viruses are recent additions to the list of threats, the latter not just as a cause just of illness but also a small but significant risk of microcephaly (small head) developing in pregnancy. On the other hand, it is comforting to note that the widespread research in the development of new vaccines may help to prevent many of these infections and adds hope for the future.

Peter Watkins is a member of the Dulwich Society’s Local History Group, who, before he retired, was Consultant Physician and specialist in Diabetes at Kings College Hospital.