VIRAL LOAD is defined as

"the amount of a virus " in macmillian.

It uses "amount" for "virus" (which is uncountable/countable???).

BUt is uses "a virus" so are they using "amount" for a countable noun here?

Or are they using it as amount of a particular type of virus?

Am confused...

It's a form of medical jargon. Look here for details.

englishnewbieVIRAL LOAD is defined as"the amount of a virus " in macmillian.
In my opinion it should be "the amount of virus" as in the article Clive referenced.

You often have a choice of the countable or the uncountable version of a noun. Which one you choose will depend on the viewpoint you take.

But in any case, "amount" goes with uncountables and "number" goes with countables, and the use of "a" or "an" means the countable version is being used. What was written in MacMillan certainly seems to violate this principle. The only way around this difficulty is to say that MacMillan meant "the amount of a certain kind of virus".

Teachers: We supply a list of EFL job vacancies
'virus' is countable. The plural is 'viruses'. There are a number of viruses that cause a flu-like condition" swine flu, bird flu etc.
'viral load' is not referring to 'how many different viruses', but the amount of one virus that is in a patient's body.

Why is grammar so difficult.... Emotion: sad
Students: Are you brave enough to let our tutors analyse your pronunciation?
 CalifJim's reply was promoted to an answer.
Thanks for that reply.

I think I am more clear now.