So the verb פרח (blossom) is not correct with respect to birth of a body itself, only its fruit and growth. And thus, in a place where the verb פרח refers to the birth of a plague, the sages of blessed memory interpret it to mean its spread. And in a place where they are unable to explain it as such, they will borrow its interpretation from the topic of buds of flowers and their varieties.

And the language פשה (spread) can be found on a plague that returns, and there is a homiletical interpretation⁷¹².

footnotes: ⁷¹² Leviticus 14:44.