[Nightedge]

-Frequent mutation of the genes results in the emergence of new subtypes [...] Since the dropping from diseased chicken may contain the virus, be sure to wash your hands with soap and water after contacting chicken.


My friend told me 'frequent mutation' is wrong and it must be 'frequent mutations', the plural being the only correct form. In logic I think it is reasonable, because when it's 'frequent', there must be more than one: plural. But when I think of 'mixed reaction', which is in the singular, I am not so sure about it. Do you think 'mutation', singular, is wrong?