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https://theconversation.com/new-virus-catalogue-reveals-which-pathogens-pose-the-greatest-threat-283599>
"In a typical year, scientists discover two or three viruses that have never
been seen in people before. The number fluctuates, but the trend has been
fairly steady since the 1960s.
Most of these viruses attract little attention, and my colleagues and I have
often had to search through old medical papers to find any mention of them.
Some viruses disappear entirely and are all but forgotten. At the other
extreme, the discovery of HIV-1 in 1983 and Sars-CoV-2 in 2020 presaged the
Aids and COVID pandemics, respectively. Both have killed tens of millions.
The next time a scientist finds an unusual or unknown virus in a patient –
probably in the next few months – how will they know whether it could lead to a
public health emergency on the same scale as Aids or COVID? My team at the
University of Edinburgh has been using the lessons of virus history to help
answer this question.
Pandemics come in many forms, but in recent times the biggest culprits have
been viruses with genomes made from RNA (rather than the more familiar DNA).
Thousands of RNA virus species have been identified, and there may be millions,
but only 239 infect humans. We recently published a catalogue that helps
pinpoint the riskiest ones.
The type and severity of disease are important indicators, but there will be no
pandemic unless the virus can spread between people. That could involve
physical contact, or inhaling airborne particles, or exposure to blood or
faeces, or the bite of a mosquito or tick.
For two-thirds of the viruses on our list, an infected person is highly
unlikely to pass their infection on. These are known as zoonotic viruses,
meaning people usually catch them from animals rather than other people. Rabies
is one example.
That sounds reassuring, but viruses evolve quickly and there is an
understandable concern that a zoonotic virus might acquire the ability to
spread among humans. That’s why scientists are so worried about bird flu. But
there is no documented example of an RNA virus doing that. Rabies hasn’t, even
though there are tens of thousands of human cases every year.
A much greater threat comes from viruses that already have the ability to
spread from person to person. They might become even more transmissible – as
did a series of Sars-CoV-2 variants – but they crossed over from animals
already able to spread among people. In the distant past, that was the likely
origin of measles, mumps and rubella, along with dozens of viruses associated
with colds and gastrointestinal infections."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
