If a virus kills its host, how can it survive millions of years? The best virus is the one that makes its host mildly sick or not obviously sick so that it lives as long as possible.
That's an excellent point.
A virus is, by definition, a parasite.
Parasites can only live as long as their host also lives.
Human viruses have evolved to "co-exist" with their human host for many years, occasionally causing disease, but generally not killing their human host. (at least not until the virus can first spread to new hosts!)
Viruses that kill humans, like HIV or the novel coronavirus, are NOT human viruses.
HIV is an ape virus that co-exists with its ape host for many years.
The novel coronavirus is a bat virus that co-exists with its bat host for many years.
The problem is that viruses can occasionally "jump" from one species to another, and that can be fatal.
Well, there's the psychological aspect:
Why are scientists surprised to find "dormant virus"? Because they ignored it so long?
Scientists are human, too. Nobody likes to think that there can be viruses hiding out inside of them. So they simply prefer not to think about it.
But there's a more historical aspect as well:
- In the early 1970's the U.S. CDC effectively declared victory over infectious disease, saying that the success of the public vaccination programs begun in the 1950's had effectively wiped out infectious disease. (Yes, they actually said that!)
- Any remaining disease, then, the CDC declared to be "chronic diseases" due to "lifestyle choices", such as smoking, diet, and exercise.
- As a result, U.S. government funding agencies declared that they were going to be shifting their research funding from infectious disease to "chronic diseases" due to "lifestyle choices".
- In just a few years, hundreds of virologists lost their jobs and there began a surge of epidemiologists looking at "lifestyle choices".
- Although this happened almost 50 years ago, we are still suffering from the entrenched biases that were created back then. To see this, simply take a brief look at the current CDC webpage for "Chronic Disease": https://www.cdc.gov/chronicdisease/about/index.htm
- For more information on this whole history, see the attached paper by the great epidemiologist Arthur Reingold. (Who, coincidentally, is also a PACE trial critic.)
I miss humility in science.
Humility may still exist in science.
But you never hear about it because humility doesn't create headlines.
And if you can't create headlines, you can't raise money for your institution.
And if you can't raise money for your institution, you won't be promoted or receive tenure.
Which means you may decide to leave science, taking your humility with you.
So maybe humility does not exist in science, after all?
I've always wondered if stress of any sort can cause the viral particles in the CSF to get into the brain, through a sudden weakening of one part of the barrier. Temporarily.
That's an excellent point.
Yes, there are certainly conditions where the blood-brain-barrier can become "leaky".
When the blood-brain-barrier becomes "leaky", viruses and other biological particles can leak from the CSF into the brain, and viruses in the brain might leak backwards into the CSF.
One example of this is severe viral encephalitis.
In severe viral brain infections, the neuroinflammation gives way to full-blown classical inflammation, with a leaky blood-brain-barrier and swelling of the brain.
In this case, you might actually be able to detect some virus in the CSF.
Another example of a leaky blood-brain-barrier occurs in menstruation.
Right before, and during menstruation, the lower level of estrogen causes the blood-brain-barrier to become slightly more permeable. Some have speculated that this might contribute to pre-menstrual syndrome.
Hope this helps.