I suspect we are all amateur virologists now that Covid 19 has tormented us so initimatey.
In previous posts I have been fascinated as to why bats and birds in particular can host, apparently without harm, so many viruses. Such musing begs the question as to what viruses do we host without pathological signs.
This question takes centre stage with a new obsession with the ‘symptomless carriers’ of Covid19 as to whether they are infectious or not and how long they host the virus. Clearly some are infectious some are not and no-one knows for how long they will test positive or whether they will test positive sometimes in the future or not.
In reading for this post I have learned of the human ‘virome’, that is our endemic biome of viruses. Suffice it to say there are many and at least five can be detected simply by sampling likely sites on the body and these include HPV, Herpes 6 and 7. The trouble is that these are sampled from bodily fluids which is the part of the virome ecology in a situation where viruses are being shed from a dormant phase within the cell into their surrounding fluids. This is the so-called lytic phase as opposed to the latent phase.
As a non-virologist I do not know what tips the balance between latent and lytic phases or indeed whether low level non-pathogenic release of viruses is ‘normal’ or infectious to others.
I do know that under stress the lytic phase causes the release of countless viruses which having so to speak ‘gone too far’ may elicit an immune response from the body along with pathogenic symptoms but in any case crucially has the ability to infect others. Anyone with Herpes knows what stresses will bring on an outbreak of symptoms.
This post however is in response to the dreadful data on the extinction of wildlife since the 1970s. Two thirds by one estimate and largely due to habitat loss. Habitat loss is the most effective and obvious stressor for wildlife and it is now well known that certainly in bats and birds this tips their viromes into a massive, shedding, lytic phase.
It is well known today that viruses such as SARS, Covid19, and the deadly Ebola have bat hosted reservoirs. It looks like the HIV pandemic had its origins in primates as the simian immuno virus.
Close contact with wild-life viral reservoirs provides the opportunity for the species jump.It is a rare occurrence fortunately and usually is a wrecking-ball to the new hosts as they struggle to find an accommodation with the new virus. One thing is for sure and that is as we drive species to extinction, stealing and destroying their habitats as we move in on them that they are under stress!
My guess is that whatever viruses they have will be being released like there is no tomorrow ( for them there is no tomorrow) and we will come across more of them and be infected by them.
How ironic if our drive to wipe out these creatures means that we sign our own death warrants thanks to viruses that one lived in peace.
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