Dogs, cats, chooks, biodiversity…and viruses

Which one of the above is the odd one out?

Answer: none.

The world is a pretty tangled place, and pretty well everything in it is linked.

This is the gist of our recommended lockdown reading for the month: On Pandemics: deadly diseases from bubonic plague to coronavirus, by David Waltner-Toews [Black Inc 2020]. This  is an update for COVID 19 times of his 2007 book, The chickens fight back: pandemic panics and deadly diseases that jump from animals to humans. As you can tell, it’s a cheery read, made so by the writer’s obvious affection for viruses, bugs, ticks, fleas, rats and other discomforting things. Five minutes into it and you’ll be slightly surprised to be still alive, given the number of threats to your existence hovering over your head, or maybe gazing at you through the eyes of your beloved cat. Viruses don’t pop out of thin air: they have often been living quite comfortably in other creatures, only to emerge when that arrangement has been disturbed by humanity…

One important lesson from this book (among many), is the writer’s clear outline of the link between ecological disruption and virus borne diseases. Broadly, his argument is that viruses which have found a home in wild places are forced to relocate to humans when these invade those places; and that biodiversity is an important barrier against pandemics. Here are a few typical quotes:

‘Triatomine bugs originally lived (happily?) in free living forest animals in south and central America. With deforestation, some bugs that were originally sylvatic….seem to have developed a penchant for certain types of human dwellings.’

‘…populations of plants, mammals, birds and insects living in ecosystems with low biodiversity tend to be more adversely affected by host-specific disease, and more effective at spreading it, than populations in ecosystems with high biodiversity…’

‘…Lyme disease was less likely to occur in more biologically diverse habitats, since the ticks and the bacteria they were carrying were less likely to find suitable hosts on which they could feed in such habitats…diverse habitats, which buffer against disease, are resilient, which means they have the ability to adapt and change.

Waltner-Toews  paints a complex picture, but the general thrust of it is: biodiversity is good for the health, in more ways than one. He makes it clear that this fact applies to cities as well as rural areas. Green belts, complex streetscapes and biodiverse gardens can all be barriers against disease. And he has an intriguing set of reflections on the value of household pets–and their possible dangers.

All of which is relevant in the context of the current questions being asked about the origins of COVID 19.

There are many other dimensions to Waltner-Toews book, especially his strong argument that poverty is a major factor in the damage done by diseases. But we’ll just leave you with this, er, fun fact: Did you know that the global body mass of commercial chickens now exceeds that of all other birds combined?

On pandemics can be had from Stonemans Bookroom in Castlemaine.