Z is For Zoonosis

A University of Edinburgh study found that, of the more than 1,400 infectious diseases that damaged the health of our species, more than 60% were capable of spreading between humans and animals. Diseases that humans can catch from animals are called zoonoses and those that go back into animal populations reverse zoonoses. Matthew Baylis has provided a very useful commentary of how all this relates to the Covid-19 pandemic (https://www.theguardian.com/commentisfree/2020/nov/10/the-covid-carrying-danish-mink-are-a-warning-sign-but-is-anyone-heeding-it). Covid-19 is certainly a zoonosis. We got it from bats, possibly aided and abetted by civit cats and pangolins. The disease has now passed into animals on mink farms in Denmark (there was a brief outbreak in farms in the Netherlands before they dispensed with fur farms). This was a reverse zoonosis, as the animals presumably caught the virus from infected workers. Sars-CoV-2 is a retrovirus. Retroviruses are mainly made of Ribonucleic acid (RNA) with associated proteins. The development of vaccines, for protecting human populations, have focused on the surface spikes that the coronavirus (that's why it's called a coronavirus) uses to access human cells. Mutations are easier in an RNA virus than in infective agents with DNA as a base. It appears that the virus in mink has mutated, changing the nature of the spike (possibly to make it easier to infect this animal). The mink-derived virus has clearly now infected human workers on the farms. If the spike has changed, it could negate any of the vaccines currently being raised to treat humans. Even worse, the mink's close relative is the ferret, much used in medical research because it has a respiratory system comparable to humans (mink and ferrets, don't, however, use tissues when they sneeze). It has also been found that domestic cats (another carnivore) can catch Covid-19 (although, to date, there is no evidence of cats passing it back to humans). Clearly, the situation is worrying as there appear to be a growing number of possibilties for coronaviruses to lurk in (and mutate?) in farmed and companion animals, before being passed back to humans. This is going to make controlling the virus much harder. Two more worrying pieces of information. The Danes (the biggest farmers of mink), originally proposed a cull of 17 million animals in fur farms. This has now been blocked by a vote of Danish MPs, on the grounds that it damages livelihoods (https://www.theguardian.com/environment/2020/nov/09/denmark-drops-plans-for-mass-mink-cull-after-covid-mutation-fears). Coffee 'cherries' are also still fed to farmed civit cats. The beans are recovered from the animal's faeces, to produce the world's most expensive coffee. You can't help wondering about humans and their sense of priorities!