I take no credit from anything from this guide, username Allhailspicy found this method and gets all the credit, using this method I got this achievement the first try and I got 4 biohazards out of it.
Guide:
First off, Gene setup:
ATP Boost
Aquacyte
Sympto-Stasis
Genetic Mimic
Extremophile
1. Start in China
2. Evolve the following symptoms: (order does not matter)
Rash
Nausea
Coughing
Cysts
Anaemia
Haemophilia
Hyper Sensitivity
Abscesses
Pneumonia
Sneezing
Sweating
Vomiting
Diarrhoea
Skin Lesions
3. Evolve Water and Insect 1 then Water and Insect 2
4. Evolve Drug Resistance 1 and 2, then Cold and Heat Resistance 1 and 2
5. Evolve the following symptoms:(order doesn't matter, but is recommended)
Insomnia
Paranoia
Seizures
Insanity
Paralysis
Coma
6. Evolve Neural Atrophy 1, 2, and 3, Then Genetic Hardening 1 and 2
7. Evolve Total Organ Failure if it has not mutated yet.
(This is optional but you could choose to evolve Necrosis if Total Organ Failure has already mutated.)
8. Remaining DNA is best put to evolve Genetic Re-Shuffles to lower cure progress which increase high score
Now just wait until your Prion plague eradicates humanity. I hope this guide has helped you beat Prion in mega-brutal difficulty. In my experience, better high scores are obtained if you're lucky enough to mutate certain symptoms. In this strategy's case, mutating Necrosis, Dysentery, and Total Organ Failure would save you a lot of DNA and would infect and kill people faster.
Source:
http://icspicy.blogspot.com/2014/04/plague-inc-prion-mega-br...