On 29
th October 2020 the Intergovernmental
Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) released
a major report entitled “
IPBES Workshop on Biodiversity and Pandemics”. This
looked at the links between environmental degradation and biodiversity loss and
the incidence of pandemics. These links have been known about for many years,
but COVID-19 has really focused attention on the problem.
Ruth Valerio posted a link to the report on Twitter on 30th
October and Justin Thacker responded with three tweets:
What we're doing to
the environment is atrocious, but we should be careful about linking everything
to it. The evidence linking flu pandemics to environmental behaviour is not as
strong as this report suggests. It is true that urbanisation and international
travel increased the speed of transmission, but it's entirely possible it would
have spread globally just at a slower rate without such factors. Flu pandemics
are not the same as other zoonoses, and can occur without environmental
degradation. The so-called Spanish Flu is evidence of that.
Ruth and I were co-authors of the recent Grove Booklet, “
COVID-19: Environment, Justice and the Future”, and I wrote the section on the origins of
COVID-19. So Ruth asked if I could reply. I pondered a few tweets, and decided
it was too complex for that! So a short blog.
One thing to say is that the report is really good, bringing
together a huge amount of literature in a logical way. So any criticisms should
be seen in that light, and are certainly not intended to undermine the main thrust
of the report (I am mindful of minute criticisms of the IPCC reports which were
used by sceptics to try to say that the whole reports were rubbish). But Justin
has a medical background and I am a scientist, and there is a place for
discussion of these issues in a fair and open-minded way.
Firstly, I totally agree with Justin that we should not
attempt to link everything to environmental degradation if the links are tenuous
or do not exist. I have similar worries.
What does the report have to say specifically about
influenza (flu)? There are 52 mentions of influenza in the report. It begins by
stating, “The majority (70%) of emerging diseases (e.g. Ebola, Zika, Nipah
encephalitis), and almost all known pandemics (e.g. influenza, HIV/AIDS,
COVID-19), are zoonoses – i.e. are caused by microbes of animal origin. These
microbes ‘spill over’ due to contact among wildlife, livestock, and people.”
It is the case that the origin of most influenza outbreaks,
including the so-called Spanish Flu, seems tied to zoonosis, but in most of these
events it is more likely that it was domesticated animals that were the source
of the virus (particularly birds and pigs). I think if I were writing something
with the title “Biodiversity and Pandemics” I would want to be clear about
this. I would perhaps have a brief mention of influenza pandemics and outbreaks
and then concentrate on the epidemics and pandemics that were caused by
interactions with wild animals. In fact, that was the approach I took in our
Grove booklet. The argument is strong enough without invoking influenza
examples and muddying the water.
I would agree with Justin on his urbanisation point.
COVID-19 would have spread more slowly with less urbanisation, and we can even
see this at the moment in the UK where rural areas have lower infection rates
than urban. I disagree though on international travel. The snag there is that a
virus can spread around the world before it is properly recognised and a local
lockdown can be arranged. Wuhan was probably an example of this.
So largely I find myself in agreement with Justin, but again
I want to emphasise that the report is an important and useful piece of work. We
can quibble about the details, but we should certainly not deny the main
message.
Dr Martin Hodson
