That's not entirely correct. There are 2 different forms of HHV6. HHV6B is present in almost 100% of the population[1] (but not quite 100%). HHV6A is less frequent in Japan, North America, and Europe. It can also cause problems for infants when they first acquire it. From the same link:

>HHV-6 primary infections account for up to 20% of infant emergency room visits for fever in the United States

The test can be used to assess viral load, which may indicate other issues, I'm told. (I'm not a doctor, though.) If you have a very high viral load of HHV6, it may indicate something else is going on. However, that doesn't mean it was necessary in this patient's case. But the test exists for legitimate reasons.

[1] https://en.wikipedia.org/wiki/Human_herpesvirus_6#Epidemiolo...

what's the point of ordering a nonsense lab test? Is a HHV-6 test significantly cheaper than one for HHV-2?

Order a test that comes back almost 100% positive then claim it was another test which requires treatment which generates a profit.

Ok, that's a more extreme form of malpractice than I had in mind. If true, this guy should never practice medicine again.