As the world battles Covid-19, it will interest us to know that India has been in the frontline of similar battles with epidemic diseases in the past.

120 years ago, cholera, smallpox, plague, and malaria accounted for 24 out of 40 deaths per 1000 people in South Asia. If these four diseases did not exist, lifespans would be similar between Britain and India then. By 1940, deaths from the four diseases fell below 14 per 1000. Why were these diseases so deadly around 1900, and why did they become weak after that?

Epidemic history raises questions like the ones the world tries to answer now. The battle to contain an infective disease needs answering three questions above all.

1. Scientific – Question of etiology or origin. The development of vaccines or treatments depends on this knowledge.
2. Sociological – social activities like migration, choice of food and water, control over property, settlements, even religion and politics, acted to turn isolated cases of illness into an epidemic. What were these practices?
3. What do public and private healthcare do once there is enough knowledge of etiology and transmission? Why do some actions work, and some don’t?

History also tells us that each episode is unique because bacteria, virus or parasites have their own biographies, social practices change or they matter differently, and every episode exposes healthcare to a new challenge.