Unseen enemies – germs invisible to the naked eye and viruses invisible even under the light microscope – have ravaged humankind since prehistoric days. The fight against them is waged on many fronts. Most visible is the family doctor prescribing antibiotics for Grandad's bronchitis. Largely invisible to the general public, however, are the public health institutions combating the invisible enemy behind the scenes. This work means that no one today wakes up saying, ‘Thank goodness I don't have smallpox this morning’. This is the story of one such public health institution – the National Institute for Communicable Diseases (NICD) of South Africa.

Before recorded history there was already evidence of tuberculosis (TB) in the bones of prehistoric humans. The dreaded smallpox, a disease of great antiquity, was known to the ancient civilisations of China and India some twelve thousand years ago. The ancient Hindi civilisations in India even had their own special smallpox deity – the Shri Sitala Devi. Clear evidence of the scourge is visible in the mummified head of Pharaoh Ramses V, 1160 BCE. Centuries later smallpox was to bring death and misery to the royalty of Europe, to world leaders of several countries of Europe and North America, and to millions of the common people throughout the world.

Similarly, the Justinian plague, during the reign of Emperor Justinian I (527–565 CE), killed millions and was a portent of the Black Death catastrophe that swept through Europe some eight centuries later (1346–1352), and was estimated to have wiped out about one-third or more of the population of Europe.

These are but two examples of massive epidemics of communicable diseases, which continued to devastate human populations right up until the twentieth century. Between February 1918 and April 1920, three waves of the devastating Spanish influenza pandemic killed between 25 and 50 million people, considerably more than had died from the hostilities of the preceding Great War.

It is nearing a half-century since our vaccines eradicated smallpox from the planet; we are closing in on doing the same for polio and perhaps a few other communicable diseases. Modern medicine, advanced science and state-of-the-art technologies now appear to be able to deal pretty adequately with the communicable disease afflictions of yesteryear. But have we reached a stage, with the scientific armoury at our disposal, to be able to relax our vigilance? Are we done with communicable diseases?