How to Design a Plague that Causes Insanity?

Question

Has a loose base in this earlier question of mine, although today we will be working with modern (roughly) tech levels and bacteria. It was pointed out in the accepted answer that bacteria might be better at causing my desired symptoms because at large they are already developing resistance to many antibiotics.

I have a story in which my characters find themselves returning from a camping trip to find society in the process of breaking down. Why is it breaking down? Well, it all started in an American biological weapons lab in Uganda...

Background:

A strain of antibiotics resistant Bubonic Plague discovered in a small village was being experimented with in an effort to make it deadlier. In short it worked, but the downside was that it was not very contagious and could be contained using standard quarantine procedures.

It was designed to not only cause swollen lymph nodes but to also induce mild insanity that causes rage(think enraged schizophrenia). People infected have a two day incubation period, after which both the physical and physiological symptoms start to kick in. By the time the infected go terminal they are raging lunatics.

To make things worse, a terrorist sleeper agent disguised as a lead scientist who miraculously cleared the 48 hour long screening added genes that make it airborne. He then managed to sneak it out and release it in the surrounding villages before his treachery was discovered and he was promptly shot.

If you want, you can liken the infected to zombies (the worst kind: the kind that generally know how to use guns!). They do possess rudimentary communication skills and can (in theory, at least) coordinate ambushes and whatnot.

Question:

How would I go about designing a strain of Yersinia Pestis that achieves the desired effects in the background?

I am interested in exactly how I could go about getting the bacteria to the brain and what they would have to do that could cause the mild insanity above.

I am also interested in determining how plausible the scenario above is and patching it up to make it more realistic (so along with your critique I am open to suggestions).

Answer 1

A more likely disease that has the effects you desire is Toxoplasmosis. The parasite affects the brains of rodents, causing them to lose many of the defense reactions they have around predators. Once the vector is eaten, the disease then cries out the remainder of the life cycle in the host, eventually being shed into the environment through the feces of the host.

The evolved/mutated/genetically engineered parasite would be have a similar life cycle to the natural version found in cats, possibly using commercial ranches or factory farms to find hosts and being consumed by humans in poorly processed or undercooked meat. If people in a food processing plant become infected, the quality control begins to suffer and more and more infected meat becomes available (and soon people who's ability to cook is affected are serving more infectious meals, spreading the cycle).

For the effects you want, the Toxoplasmosis parasite is slowly consuming or poisoning the higher cognitive functions of the brain, affecting the ability to reason, make rational/moral choices and eroding functions like compassion and inhibitions (making infected persons rather dull witted sociopaths).

How long they live before succumbing to the disease can be adjusted by various factors, but in general, the longer you are infected, the greater the loss of reason and other functions and the less ability the infected person has to survive. Probably a period of months for the decline to set in (and the infection to spread) followed by a few weeks of sociopathic behaviour and then a rapid decline.

Answer 2

My initial thought is you build a host cell for a virus or prion (like Kuru). Possibly a bacteria that can live in the mouth, and is generally benign. It is totally transmittable over the air and so simply breathing would spread the bacteria. On reaching adult form (which could take weeks), a biological process kicks in and the bacteria turns into a prion or virus factory. Nasty. All you need is the correct secondary disease to cause sustained insanity without killing the host human.

Answer 3

I'd skip the Y. pestis route, frankly. Instead, there's a much more interesting possibility: diphtheria.

Diphtheria by itself is serious, but not particularly lethal, and it has the dual advantage of being naturally airborne, and producing a certain percentage of asymptomatic carriers. Where the story gets interesting is the result of infection by the Beta phage. This virus inserts a gene into the diphtheria bacillus which causes the bacillus to begin producing an extremely potent toxin, and this is what kills most diphtheria fatalities.

So the development process would be two-fold. First, modify diphtheria enough that it no longer is controlled by diphtheria vaccine (call it pseudo-diphtheria), making it possible to spread in the population. If you can also modify it to increase the percentage of asymptomatic carriers, that's a big bonus.

The other prong is the modification of the Beta phage to produce (obviously enough from a literary standpoint) the Omega phage. The Omega phage will induce the pseudo-diphtheria to produce a different kind of toxin. This toxin will selectively attack the aggression inhibition neurons in the hypothalamus (see http://www.scientificamerican.com/article/sex-and-violence/?page=1).

Exactly how this will occur is left as an exercise for the writer.

Oh, and I'd suggest that you rethink your 2-day incubation time. The longer the incubation, the better the chances of wide dissemination, as it muddies the epidemiological trail. With a short incubation it's easier to trace the spread of the illness, and easier to set up quarantine procedures. There's a tradeoff there - if the incubation time is too long, research on the first wave of maniacs will allow development of a vaccine before the spread becomes overwhelming. But I'd suggest that 2 days is too short.

Answer 4

I would think it would be reasonably easy to make a bacterial disease that mimics insanity. Simply insert a gene coded to produce a hallucinogen. Some hallucinogens are natural plant products, simply copy the gene out of the plant. The hard part will be identifying the gene you need.

Answer 5

Syphilis gets airborne and resistant to antibiotics. Fairly short incubation period and causes degradation of mental processes. Plus, embarrassing symptoms.

Answer 6

If you want a plague that causes insanity, all you have to do is aerosolize rabies. It already causes insanity, has a slow incubation time (measured in weeks, not days) and is 99.9999% lethal. The only saving grace is that it's a blood borne pathogen. Now, find some way to cross the symptoms of rabies with the spread pattern of measles and you have something truly terrifying.

Answer 7

Simplest answer I can think of: A bacteria that produces mercury in trace amounts as it destroys blood, spinal, and brain tissue. It could be engineered to only go after human dna so that it only affects humans. These trace amounts build up over time, and cause the bearer to go insane. The bacteria is resistant to all known forms of chemical destruction, but Radiation therapy would work.