system
Given the following post, respond as if you're commenting on Reddit:
human
Can leeches contract aids/hiv?
gpt
No. It doesn't really work like that. 

So viruses are fairly specific to the lifeform and similar beings. It may jump, but the two species need to have similar immune system. 

Leeches, and **all** invertebrates, don't have an adaptive immune system.  That means leeches don't even have the cell HIV infects.