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Some people feel that SARS-CoV-2 infection of the brain is "rare". (e.g. <10% of cases)
But can we really say that #SARSCoV2 infection of the nervous system is rare? 🤔
That's a question posed by neuroscientist Yan-Chao Li of Jilin University in his literature review and meta-analysis:
"What can CSF testing & brain autopsies tell us about viral neuroinvasion of SARS-CoV-2?"
https://doi.org/10.1002/jmv.26943
👇 Thread below 👇
#virus #virology @virology #InfectiousDisease #coronavirus #covid
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Lead author Yan-Chao Li has spent the last 15 years studying coronavirus infections of the nervous system.
The authors point out that brain infections are extraordinarily difficult to detect at autopsy, partly due to the large, inhomogeneous nature of the brain tissue and the significant possibility of false negatives:
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In addition, one more significant methodological problem has been raised by other authors.
Any viral RNA will rapidly degrade in any sample in a matter of hours, unless an RNA stabilizer is added to the sample right at time of sample collection - not at time of extraction:
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One autopsy study, performed by a group of NIH investigators, correctly treated their samples with an RNA stabilizer as soon after death as possible.
This study found much higher levels of viral RNA than studies that neglected to use any RNA stabilizer:
@trueinfections @pyrrhus @virology
It contributes to be sure, but Covid is tricky, just because someone is asymptomatic doesn't mean they're not infected--what is true during acute Covid is also true during chronic manifestations of the disease.
Great question. Unfortunately, we don't yet have a great answer.
It's challenging to detect the virus in the brain at autopsy. It's even more challenging to detect the virus in the brain in a living individual.
Therefore, new technology will likely be needed in order to answer your question appropriately...
Unfortunately, true imaging is not yet available.
And most neurotropic viruses are not detectable in the blood after the first few days post infection.
This is why polio was always diagnosed based solely on symptoms, because there simply was no poliovirus to test for in either the blood or the CSF. But doctors who took the time to carefully observe patients could usually recognize the particular set of neurological symptoms that typically come with a poliovirus infection.
Eric Pyrrhus
TrueInfections
J.H.Noyes