These pages are intended as a layman's guide to the major diseases that have impinged on history, particularly the history of Britain. Anyone requiring more detailed information on modern diseases should refer to the World Health Organisation's web site.

The most obvious diseases in history have been the plagues. These are acute epidemic infectious diseases with high mortality rates. In other words, they hit suddenly, spread quickly and kill lots of people. In this section you will find the best known plague, the Black Death, and one which was destroyed in the wild, but never cured, smallpox.

Epidemic diseases are those that affect large numbers of people in one area at the same time. This section only deals with influenza, which has the dubious distinction of killing more people in a single year than any other cause in history.

Diseases that are spread by contaminated food or water are covered in the section on poor sanitation. Here you will find cholera and typhoid.

Diseases that are spread by parasites or by proximity to an infected person thrive in poor and overcrowded living conditions. In the section entitled overcrowding you will find tuberculosis and typhus.

Leprosy figured large in the mediaeval world. Modern leprosy is almost certainly not the disease identified as leprosy in the Bible and probably not what was recognised as leprosy until the twelfth century. I have, therefore, started with a brief mention of Biblical Leprosy. This is followed by information on bacterial leprosy or, as it is known today, Hansen's Disease.

The glossary covers old names for diseases as well as a some terms that appear in the Bills of Mortality.