All right! This will be my last science meta post about Thedas for a while, unless something else strikes me. As always, thanks to everyone who’s shown an interest in these sorts of posts. I hope they’re entertaining and interesting, I know I’ve had a ton of fun thinking about them.
Part 1: Lyrium Addiction and Withdrawal
Part 2: Biology and Life History of Lyrium, and Dwarven Physiology
The Blight is two different entities: one is the coordinated attack on the surface world by darkspawn led by a tainted Old God, the other is the disease that results in infection and the creation of wastelands. We’ll be talking about the latter.
The Blight pathogen has to be something pretty elastic; it is able to infect animals, plants, and fungus. Our options for infectious agents include bacteria, viruses, fungi, parasites, and prions.
Parasites are typically fairly host-specific, sticking to well-established life cycles, so they’re out; there’s no parasite in nature that would infect both plants and animals, and when they do infect animals of different classes, typically it’s just a handful (i.e. mosquitoes and dogs both are affected by heartworm, not mosquitoes, houseflies, beetles, ants, dogs, bears, birds, lizards, etc.).
Viruses are more diversified than parasites; consider rabies virus, which is capable of infecting all mammals. However, plants and fungi, as well as birds and reptiles, would be safe from rabies. There are certainly viruses that jump entire classes of creatures - West Nile infects birds and mammals – but I really can’t name one that jumps kingdoms, affecting Animalia AND Plantae, for example; making it more doubtful that the Blight is a virus, in my mind.