. @ClareCraigPath has been getting a hard time for questioning whether an asymptomatic infection can be a disease. She has a better grasp of the philosophical issue than her critics, which tells us something interesting about the difference between medicine and biology. (1/7)

LS King was a wise US physician "Biological science does not try to distinguish between health and disease. Biology is concerned with the interaction between living organisms and their environment. What we call health or disease is quite irrelevant." (2/7)
https://www.jstor.org/stable/185276 

Medicine, and related sciences, are ways to control the world in the interests of - some or all - humans. Biology seeks to understand it. The idea of an asymptomatic infection does not make sense in biology (3/7)

A biologist might describe a virus that inhabits the human body with no obvious deleterious effects - like the many bacteria that live in our gut - with words like mutualism, parasitism or commensality but these have none of the moral force of 'infection'. (4/7)

Many geneticists think that quite a lot of human DNA derives from ancient viruses that took up residence and modified their host in ways that were either neutral or advantageous. (5/7)

One of the things we need to sort out with Covid-19 is the proper description for a virus whose effects are not necessarily visible. Should we think of it as similar to gut flora, which we ignore unless something happens to disturb them? (6/7)

The UK does not have a big tradition in the philosophy of medicine and biology - but this pandemic might remind us why it matters if we are going to avoid errors in policy and practice. (7/7)