Although that sounds alarming, zoonotic infections are actually quite common and have been a problem for Homo sapiens/humans ever since we crawled out of the primordial slime millions of years ago.
As we became agriculturalists (agriculture reduces the travel of those living a nomadic hunter-gather life) the problems of zoonoses would have got worse. Herds of animals living in a restricted environment will more easily spread infection between one another leading to greater amounts of infection in the herd (is this…”herd infectivity” rather than herd immunity!?).
Anyhow, keeping animals in one place leads to greater contamination of the environment with animal waste, and higher amounts of environmental levels of zoonotic organisms. This in turn exposes those doing the herding to higher risks of infection. All of this results in increasing transmission rates of zoonotic infections from livestock and farmed animals to humans.
Over the millennia we have evolved to deal with these types of infections. We have developed specific white blood cells called eosinophils to deal with parasites and neutrophils and lymphocytes for dealing with bacteria and viruses. As a result almost all forms of gastroenteritis, including Bank Holiday BBQ gastroenteritis, from eating contaminated meat are self-limiting problems which only require us to maintain our fluid intake in order to recover. How clever are we, big brains you know!
Over recent years there has been a rapid increase in the World’s population and as a result we have pushed our way in to new habitats containing animals which we previously had little contact with! We are also living closer together, so like the static herd, are more likely to spread disease between each other. This exposes increasingly large numbers of humans to novel microorganisms and new infections that they haven’t had thousands or even millions of years to adapt to. These new germs are the ones making us sick!
This is what has happened with all the recent viruses, all are novel, and all have arisen and crossed from other animals into humans. SARS coronavirus 1 from masked palm civets, MERS coronavirus from camels, Ebola Virus from bats and Human Immunodeficiency Virus from primates. Who knows whether the current SARS Cov2 will end up just from bats or whether it too will have another animal host?
I don’t want to scare monger but the more we push into new habitats the more likely these problems will become. I think it is reasonable to suggest that this won’t be the last time we face a pandemic, so I feel it is essential that all Governments support research into zoonoses likely to have pandemic potential. Surely SARS Cov2 shows us this approach would be a more efficient use of money than the cost of trying to deal with another pandemic after it has already happened!? The bank of England has released a report today stating the UK economy this year will see the largest decline (14%) on record, and that’s in over 300 years of records… it also predicts two consecutive quarters of decline, technically taking the UK into a recession by summer. And economy-centric President Trump won’t fund the WHO?!?
Anyway, party political broadcast over…
Here is a list of some of the current common or serious zoonoses (Covid-19 excluded) from the appendices of Microbiology Nuts and Bolts for you to mull over…
Stay sane and enjoy the weekend!