Endemic.

I always tot the word "endemic" had negative connotations.

It was kind of surprising to read Carl Trocki's sentence which says
"[T]he triad was endemic among the southern Chinese", where
the word was used in a very neutral fashion.
Perhaps he meant it to be subtly ironic but I guess it was lost on me.

Oxford English Dictionary confirms my suspicions
that the word is used to speak of negative things, like diseases.
An example would be Adam Smith's usage in The Wealth of Nations, p. 77,
where he writes "Famines are periodical or endemic in Hindostan".