I found uropthalmus to be prone to HITH if water changes weren't frequent enough, and large, and the infection usually started in the nasal passages.
They are endemic to the very clean waters in the Yucatan, where the up welling of underground rivers keep them in an almost constant water change, and immaculately clean water. The water there is also a bit brackish, which may inhibit certain bacteria, because it is so close to the sea. I took the video below in Eden Cenote, less than a mile from the Caribbean, and you can see by the clarity the water there is amazingly clean.