Does anyone know anything about bats causing health issues... like Chlamydia?

Bats do not cause chlamydia. Sorry. They can carry rabies though.

As above, I've never heard of them carrying Chlamydia... just a few other diseases.

I would say yes. Chlamydia Psittaci can be caused from exposure to the droppings (guano) of bats, birds, pigeons, parotts, falcons, etc.

From what I've read I thought Chlamydia Psittaci is an avian virus that is passed on (through great difficulty) to mammals.

I'd have thought you could get it from birds, but not bats!

Another name for it is Parrot Fever.

See this link.

Chlamydia Psittaci