Last summer concern for the environment and worries over plastic pollution dominated the news, this summer the all-engrossing topic has been the coronavirus pandemic. At first sight they don’t seem to be connected, but on closer inspection subtle links can be drawn between them. Some corona viruses affect bats, of which a particular type has recently made the jump across species and is now infecting humans. Its capacity to move swiftly from person to person has caused the global pandemic that we are currently experiencing.
Diseases which infect both animals and humans are called zoonoses. They’re not new and are often sporadic and don’t spread through the human population. Farmers may be familiar with orf, a skin-blistering virus sometimes caught from sheep. Another is leptospirosis, a disease of rats, very occasionally contracted by sewerage workers. Bovine tuberculosis, currently the source of much trouble to badgers, was in the past quite commonly a cause of disease in humans too, until the introduction of milk pasteurisation put a stop to it.
Bubonic plague, probably our most famous epidemic, killed an estimated third of all Britons back in the Middle Ages. It was a bacterial disease of rodents infecting humans, (via fleas), which spread widely and rapidly to devastating effect. Perhaps surprisingly it continues to this day in wild rodent populations, in America it still exists in racoons. Prior to coronavirus, other diseases new to humans have arisen over the last four decades. In the nineteen-eighties human immunodeficiency virus moved to humans from primates, possibly due to the consumption of “bush-meat” and since then West Nile virus,(from birds), and Zika, (from monkeys), have jumped the species barrier too.
So what makes animal disease transfer to humans? Scientists believe that habitat destruction, encroachment of human habitation into wild places, trade in wild animals and use of wild animals for food all play a part in the process. Habitat destruction, particularly deforestation, and habitat degradation, such as by pollution, bring animals into closer contact with people, disrupting their ecology and straining the equilibrium of animals and their natural population-checking diseases.
Once the diseases make the move to people, man’s propensity for travel spreads them further. Again this isn’t new. The ancient caravan routes bringing silk from China to the west were just as effective at disseminating disease as the aeroplane flight paths that brought coronavirus to Britain in 2020 – just a bit more slowly.
We should reflect that we are animals living alongside other animals, heir to the same dangers that they are and we would be wise to treat them with more respect. We may want to carry on behaving as we currently do, putting Mankind’s interest above all else, but Nature will have a way of containing us. After a pandemic like this no-one can say we haven’t had a warning.