"Well... it is hardly a conventional treatment... but then again, no conventional treatments exisst. I'm sorry, I really don't know much about that type of thing; you would have to speak to his Doctor."
No treatment indeed, Gallagher for you have indeed heard of the Lichen- as a curiosity.
The planet Floria is a rather benighted jungle world, all the more benighted for the fact that no-one will go there because they are afraid of contagion.
That's a pretty vague fear. Less than one in ten thousand beings in the Galaxy are actually susceptile to catching it, which seems to be based on a quirk of genetics that no-one has ever identified (the contagion rate is more or less identical in all species that have yet encountered it). It is also totally impossible to catch it off someone else.
The Lichen itself- named for the effect it produces, rather than its nature, which is bacterial- lives naturally in the Florian eco-system. Due to a quirk of nature, however, it is ferociously compatible with just about any bio-system. To put that in perspective, most alien biospheres have a compatibility of about zero percent with other biospheres; if the Lichen was like that the contagion risk would be about one in a billion, or less. To reach one in ten thousand is astounding.
As it is, its microbes suffuse the planet. If you are susceptible, you will catch it simply by going there. The microbes, if compatible, lodge into your skin, and then attach themselves to your bodily cells at a mircroscopic level. Once they imbed themselves, they can never be removed.
Any lifeform they are in contact with, they use as a breeding ground. An infected person starts a slow process of being consumed and turned into a plant- it mainfests itself at first in green, moss-like patches- the 'lichen'. On the skin, where the first symptoms materialise, they are simply a painful nuisance. The embedded lichen spread as years go by. Eventually they will grow in blood cells, blood vessels, bones, and organs, up to and including the brain. The lingering, painful deaths from this are quite horriffic.
"Suh a shame," remarks the nurse. "He was only there on a charity mission. The Universe has an odd sense of justice sometimes."