Kinda the spores (unless they are a macro organism) are NOT single celled organisms. The flood is actually loosely based off of that rain forest fungus that zombifies and grows out of the brains of insects. But yea spores sure quarantine wise its challenging. However ANY ONE with shields (energy/magnetic based) can prevent contamination by spore material. The brain worms are more active/semi conscious (they move and seek out host actively) so in some ways they are HARDER to quarantine.