Basically, my current thought process is to have a virus that causes one to all vital organs to fail upon reacting to its components. It has to make contact with as many people as possible, therefore has to be airborne.
The virus itself would be slow-acting, and can, for example, take longer to cure than it takes to kill, or be extremely hard to detect with countless variants.
What I have so far is:
- A pathogen resembling a normal human cell in both behavior and characteristics, making it hard to detect.
- Bolstering its heat and cold resistance enough that killing it by heating or freezing it would result in killing the host as well. (Giving it general resistances to most common decontamination methods, basically.)
- Making its hosts vitality vary by individuals, although surviving without taking countermeasures is impossible.
I believe some pseudo-science can lead to such results, although my problem lies in its spreading. If it's hard to detect in a human body, then it would be relatively easy to find while travelling by air or water, wouldn't it? And spreading it by body contact is somewhat inefficient, since it would take a long time for it to spread everywhere, and I want its transmission to be as fast as possible.
What I want to know is:
Are there elements that can attach themselves to oxygen molecules and remain undetectable? If not, then what would a "scientific" approach to making one be?
What kind of lethal elements to the human body are there that could result in organ failure upon contact, and / or cause visible effects?
Are there any air filtering methods that can cleanse oxygen molecules enough that such a pathogen would be removed?