It has been an interesting week. Not only the excitement of the Presidential Election and the looming disaster of a no-agreement Brexit, but also the rising interest in Long Covid and the Danish mink farm story. But I'll start with a question. My fellow contributor, Robin Downie
, whose essays are always instructive, discussed last week what we might mean by the word 'disease'. It is a question that is asked often in my profession and Professor Downie explains why. So, I pose the question: what is COVID-19?
We know that people may harbour the virus without showing any symptoms, so just being infected is plainly not a disease though it may be a threat to others. However, many people do indeed fall ill and some die, so at some stage it becomes an illness and whether its victims accept that they are ill depends on its severity and their own resistance to complaining about any symptoms they suffer.
We have a range of descriptive terms to use in answer to the question, how are you? They reflect the fact that we all hover uncertainly between perfect health and illness – very well, thank you; fine or okay (with a face that indicates you are not); not too bad, a bit off colour, peely wally; poorly, ill, rotten, bloody awful. My answer tends to be, still alive. Your doctor may say you have a cold, a bit of a virus, a touch of flu, pneumonia, heart failure, or now, Covid. But the diagnostic label isn't enough because it doesn't describe how ill you are. An American colleague jocularly defined the normal person as someone who had not yet been fully investigated.
To give more information about COVID-19, we have Covid Pneumonia and more recently Long Covid. All doctors would recognise the first of these as a disease; if you suffer from it you feel ill. But Long Covid? You feel ill but the doctors said you were cured. What is it?
The naming of diseases
The need to name this feeling of illness originally came from a desire to bring order from confusion. Hippocrates noted the variations in human health in relation to seasons and in the 17th century Thomas Sydenham started to classify illness with respect to the association of symptoms and evidence from observation, what all medical students still learn as history and examination.
By the 18th century, the Scottish Enlightenment physician, William Cullen, produced a classification of disease into fevers, neuroses, cachexias and local diseases. His model was Karl Linnaeus's classification of plants. This was made more comprehensible by Giovanni Batista Morgagni's De sedibus et causis morborum
(on the sites and causes of diseases), published in 1761 when he was 80 years old, in which he described the pathological features of many diseased organs found on dissection of the human body.
The importance of this is simple to understand; if an illness has a name, it can be defined, its natural history described and its response to treatment investigated. This is the foundation of modern medicine and is why someone who develops symptoms attributable to infection by the virus known as SARS-CoV-2 can be said to have the newly named disease COVID-19. But of course, it's not quite so simple, since this label covers such a range of responses to the infection. The label doesn't tell you what is in the parcel.
COVID-19 and Long Covid
We now know that COVID-19 has many manifestations, from loss of smell to failure of multiple organs. Like most infectious diseases, it does not have specific pathological features, though blood clotting, pneumonia and inflammatory changes in major organs are commonly found in severely affected people. Such patients show evidence in their blood of an over-active immune response which is thought to trigger the organ damage, and which fortunately has been found to be prevented in many cases by steroid treatment.
We know that most COVID-19 patients recover fully but that a proportion have lingering symptoms of a non-specific nature over weeks or months; these include fatigue, loss of smell and taste, cognitive or mood changes, headaches, bowel upsets, and muscle pains. This has been called Long Covid, and no doubt its right to be called a disease will be questioned by some. It is reminiscent of what used to be called Royal Free disease and is now known as Chronic Fatigue Syndrome (CFS); chronic fatigue is a good but incomplete descriptor. It usually follows a viral infection and shows little or no detectable evidence of organ or physiological dysfunction. Natural scepticism may lead some doctors to attribute it to psychological causes, while others will search for some radiological or biochemical abnormality. But to the patient, it is certainly a disease with both physical and psychological components.
Unfortunately, it will require time to understand this newly described condition, Long Covid, and its natural history, but my guess is that its symptoms will gradually improve, as in most patients with CFS that I have personally looked after. Professor Downie proposed that doctors might concentrate on the patients' perceived problems; he might not know that this is exactly what we were urged to do some 40 or more years ago and it was indeed very useful to make these problem lists in the patient's hospital notes. It brings into focus the conflicts between cure and care. I suspect it is less used now but would certainly be useful in the management of Long Covid, since treatment is perforce symptomatic.
By analogy with CFS, which has a strong tendency to relapse, especially if the victim tries too hard to get fit again, a slow rehabilitation with psychological support and graduated increase in activity is likely to be necessary. I would expect that controlled prospective studies of such patients, appropriately defined, will eventually be available to guide doctors' management.
In April 2020, an animal attendant with COVID-19 in the Netherlands unknowingly infected his charges on a large mink farm. They showed a 3-4% mortality over four weeks until the epidemic waned. Those minks that died had severe respiratory infection, similar to the human disease. Many animals escaped with no or mild symptoms. However, by June two animal attendants in another farm had caught the disease from their minks and a decision was taken by the Dutch Government to cull all minks in the country. In Spain in July, a family of mink farmers caught the disease from their animals and after other cases were reported a cull of minks was ordered.
And now a similar episode is reported from Denmark and the virus in several of its human victims is reported to have a mutation in one of the proteins that constitute the spikes. This mutation is presumably an adaptive response to facilitate its infectiveness in minks, but unfortunately it does not make it less infective to humans who can then pass it on to others. This is potentially serious as many of the vaccines on trial for the human disease are targeted at the spike proteins (including the vaccine just announced to be effective) and this mutant may thus be resistant to them. Prompt action has been taken to restrict spread of this organism by Denmark and other countries. This is an evolving story as I write, but it illustrates the dangers implicit in factory farming. At worst, it could require completely new additional vaccines; at best, it probably signals the end of mink coats and the trades involved.
Humans, like viruses, display an infinite variety, though our mutations are less relevant to our immediate fate. Some people are well-adapted to their environment and those that are not may suffer for it. For the last four years, many people of good will have cringed at the appalling behaviour of the American President. One could not imagine anyone less suited to the dignity and requirements of that office. It is to me a matter for rejoicing that the strong sense of decency of a majority of the American public has led them to reject him. This should remove one danger to civilisation, but Mr Biden will not have an easy task. At least he is well prepared and recognises the problems.
This change is good news for international cooperation, for WHO, for action on climate change and epidemics, and for science generally, but not for Brexiteers. Mr Biden may be thinking, like Mr Churchill on VE Day, 1945, 'We may allow ourselves a brief period of rejoicing but let us not forget for a moment the toils and efforts that lie ahead'. Now those toils include dealing with COVID-19, the economy, and climate change. It is interesting to note that they all require our collaboration if he is to be successful, as was the case in 1945. And, as then, we shall all need to adapt to a less comfortable environment, vaccine or no vaccine.
Anthony Seaton is Emeritus Professor of Environmental and Occupational Medicine at Aberdeen University and Senior Consultant to the Edinburgh Institute of Occupational Medicine. The views expressed are his own