Basic Mechanism for Incurability: Biofilms
A significant problem in hospitals is how to combat bacteria the form biofilms. These biofilms provide effective protection against a great many decontamination techniques both inside and outside the body. Let's build a disease around that mechanism.
The pathogen's metabolic pathways closely resemble those of a normal human cell.
Since the host immune system uses receptors on foreign bacteria to identify threats, our pathogen has considerable ability to mimic the host's receptor. (The pathogen mimics the extra-cellular receptors that the host uses to distinguish between self and not-self.) Since the immune system recognizes the pathogen as "friendly", it is not attacked. Theoretically, it would only take a very small amount of the pathogen to induce death in the host.
Spread within Host
Form plaques/biofilms in capillary blood vessels that chock off blood supply to periphery areas. Once blocked off, the bacteria goes into anaerobic mode and starts pumping out a nasty toxin similar to botulinum toxin and more plaque to coat the infected area. The toxin kills off the surrounding tissue then uses the dead tissue as raw material for building a plaque wall. Hiding behind the plaque prevents clean up by the immune system or the lymphatic system.
Bacteria that haven't lodged anywhere continue to reproduce as quickly as they can. As plaques build up in major arteries and veins, the body will start to experience overall decreased functionality. In some/many cases, plaques that form in the heart will duplicate symptoms of Atherosclerosis, though a thousand times faster.
- Difficulty breathing
- Irregular heartbeat
- Black pustules in the extremities.
- Loss of cognitive ability
- Severe organ pain
- Black phlegm in coughing
- Extreme fatigue
- Severe itching around pustules
- Irritation to the lung lining causing severe coughing
Spread between Hosts
Given the pathogen's ability to create strong biofilms in all environments, they may be able to last for long periods outside a host. Strong coughing by the victim will spread the pathogen through the air and depositing it on all manner of surfaces. Once the pathogen lands, it forms a biofilm sufficient to preclude destruction by bleach or any other strong chemical sanitizers. This ability makes sterilization incredibly difficult and allows the bacteria to popup again at a later time to reinfect a host.
Being airborne dramatically increases the pathogen's ability to spread itself. A good cough or two by an infected person in a large, busy international airport such as JFK, Paris, Tokyo, or Heathrow would spread the pathogen across the globe in short order.
Also, under certain atmospheric conditions the pathogen will form into spores and pop off the colony to float around and infect someone else. Consider how hard it is to contain a mildew or mold invasion. That's exactly how hard it is to clean up this pathogen.
Defeated Decontamination Mechanisms
Targeted viral infections - Won't work because you'd kill the host along with the pathogen.
Heat - In the food safety business, it's well known that you can't kill the spores that become bacteria. So even though a food may be sterilized after cooking at food safe temps, if the food is then left at room temperature then it will rapidly become contaminated again. Getting heat high enough to kill the spores usually means making the host into charcoal too.
UV - Biofilms take the brunt of this kind of ionizing damage. UV filters don't work against bacteria encased in UV blocking material.
Chemicals - Hospitals currently fight biofilms that evade such strong oxidizers as bleach. This pathogen has a similar biofilm capability.
Impossible to stop
By mimicking a host's receptors it forms a very difficult to hit target for the immune system. Any drugs that boost immune system function will not help here. By mimicking a host's metabolic pathways, any drug that targets them will also target the same pathways in the host, leading to death.