A few years ago, I had never heard of parechovirus. Echovirus yes, but not “parecho”.

I would not have been alone…

However our ability to diagnose such viruses now (using PCR) means that myself and my colleagues now need to go and learn something about such viruses.

And here is a summary of (more or less) all I know about parechoviruses…

• I know that the “ECHO” bit is an acronym (Enteric, Cytopathogenic, Human, Orphan). That probably tells me as much as I need to know about the background information on the virus. I have no idea what the “Par” stands for. Any help welcome…
• You can theoretically perform viral culture for parechovirus, if you are happy to wait a couple of weeks for the result. We aren’t, so along with most other diagnostic laboratories in the world now, molecular methodologies have taken over.
• Parechoviruses are the 2nd most common cause of viral sepsis like illness and meningitis in infants (after enteroviruses). Therefore if you are performing a CSF PCR panel in children, then it must include parechovirus. (Unlike enteroviruses, parechoviruses are a relatively rare cause of infection in older children and adults)
• In complement to the above, parechovirus infection in the CSF does not give a positive enterovirus PCR test. They are sufficiently different viruses.
• Unlike most other viruses, parechovirus meningitis does not cause a significant CSF leucocytosis. This has been our personal experience in the laboratory, and also that of other people in the medical literature. This is important because if, like us, you have testing criteria in place for CSF viral PCR based on leucocyte count, then you need to make neonates & young infants an exception to the rule.
• Parechovirus (like enteroviruses) belongs to the picornaviridae family, and because of this may be susceptible to the viral capsid inhibitor pleconaril. However the jury is still very much out on pleconaril, and as such I would want to be speaking to someone who knows much more about viruses than me before even considering its use in a sick child.

So I now know a little bit about parechovirus, not a lot, but enough to allow me to do my job.

We don’t need to be “walking encyclopaedias”, just knowledgable enough to function in an information overloaded world…

Michael