u/Aromatic-Sky1518

So I'm writing a story where there's an organisation like the Umbrella Corp in Resident Evil and they are harboring a parasite, feeding it, monitoring it and containing it. But during a chaotic lockdown, the glass cage breaks and the parasite escapes. Now I want to invent a new parasite that affects populations, is transmissible and is so dangerous that it can cause deaths. I don't know much about parasites but I want it to be like RE or the symbiote in Spider Man 2 game but a totally different and unique one. How do I do this???