Devastating diseases that have affected human populations throughout the ages.

Epidemics have devastated human populations throughout the ages. The 14th-century Black Death killed between 30 and 50 per cent of Europe's population. The 1918 Spanish 'flu is thought to have killed more people than died in World War I, and HIV/AIDS continues to claim millions of lives. With their uncontrollable, invisible spread and, until recent times, poorly understood means of contagion, epidemics often cause public fear that elicits all manner of responses. These responses are reflected and interpreted in different ways in the cultural and artistic productions of the afflicted societies.

In Japanese legends, for example, Chinsei Hachiro Tametomo was a celebrated historical figure who in the 12th century was exiled to the island of Oshima by his enemies. Using nothing more than his Herculean will, he repelled the demon of smallpox, and so it has been suggested that Japanese families kept prints of Tametomo in their homes as talismanic protection against the disease.

Other measures taken before the scientific discovery of effective prevention often invited satirical commentary. One 19th-century etching, illustrating self-protection methods against cholera, ridiculed the quackery associated with the disease. It depicted a man saddled with a bewildering array of remedies, including wearing a large sack of warm sand on his chest, wooden receptacles full of hot water under his shoes to keep the feet warm, camphor-soaked cotton in his ears and a soup tureen on his hat.

Alongside the widespread responses of fear and the barbed humour of the satirists, there were those who responded with individual acts of bravery by ministering to the sick. Two silver snuffboxes, collected by Henry Wellcome and donated to the Science Museum, were presented during the first two cholera outbreaks of the nineteenth century. One of them is inscribed "To Robert Fortescue, Surgeon, in testimony of the gratitude and esteem of his fellow townsmen for his humane and unceasing attention to the Poor during the awful visitation of malignant cholera at Plymouth A.D.1832."

Alongside the doctors who were active at the front-line of duty, it required the scientific investigation of infection to control or ultimately prevent the continued occurrence of epidemics. Edward Jenner, who discovered the vaccine against smallpox in 1796, is widely regarded as the "father of immunology", initiating a process by which many formerly fatal diseases are now controlled if not entirely eradicated. By deliberately exposing his case studies to cowpox, Jenner successfully induced immunity against smallpox. Jenner used a series of thirty watercolour drawings of smallpox and cowpox inoculation, now held by the Wellcome Library, to illustrate his petition for a grant to the House of Commons in 1802.

Before the advent of immunisation, understanding the source and cause of a disease could help control its spread. The epidemiology of cholera, a virulent killer throughout the 19th century, was first understood during the Broad Street outbreak in London of 1854. John Snow used sophisticated statistical analysis demonstrated that the disease was water-borne, and that the deaths were clustered amongst users of a particular London water pump.

Snow also used microscopic observation of a variety of water sources to picture their contaminating organisms, such this drawing of sewer water from Silver Street. This and other similar drawings were included in a report on cholera to Parliament published in 1855. Whilst Snow did not recognise the microbes that caused cholera such images of the microdimensional world created much fascination in the mid-19th century. At that time the microscope began to revolutionise science and eventually allowed the discovery of the causes of many diseases, including cholera in 1883.

The most modern imaging technology has allowed scientists to picture the most harmful viruses and bacteria with ever-increasing sophistication. Some have a compelling aesthetic appeal that hardly seems possible given their devastating impact. The fungus 'Aspergillus', for example, has a delicate, flower-like beauty, the malign SARS virus an incongruously delicate, dandelion-like structure, and the foot-and-mouth virus a hypnotically kaleidoscopic structure.