I recommend reading the last section regarding a 2022 update to the guide.

Select PRION and use these genes:

• Catalytic Switch
  
• Genetic Mimic
  
• Aquacyte
  
• Extremophile
  
• Ionised Helix

Start in USA and evolve Drug Resistance 1 - 2.
Don't evolve any symtomps and devolve each one mutates
Evolve Air 1 - 2 and Water 1, then Neural Atrophy 1 - 2 - 3 and Genetic Hardening 1 - 2. (If necessary evolve Heat resistance 1).
Wait for everyone infected.
Now it's time to start killing people but you have to do it slowly (but not too much).
Evolve:
1) Insomia, Paranoia, Inflammation, Seizures
2) Anaemia, Haemophilia, tumours
[The blue bubble will give you enough DNA points to evolve Genetic Reshuffle 1- 2 - 3 if necessary]
When the US population drops by 10-50 % this message will appear:


If it takes too long maybe you're killing people slowly. So evolve Internal Haemorrhaging, then devolve it after a while if people are dying too fast.
So the president is ill and he needs to be replaced by someone. You need to evolve Insanity faster than you can. This will take a while but you will receive this pop-up:


(*) Now you have to get Russia blamed by Spalin. To do that you need to evolve Cold Resistance 1 - 2. Wait again until this message appears:


Now you have to evolve Paralisys. This will prevent generals to stop Spalin. Wait again until this final message shows up:


Congratulations!

*As stated by user morfina "If you follow the Chinese instructions and save after Spalin has been elected, you can use this save to try the Russia nuked achievement too. You just have to devolve Birds 1 and 2 and develop Cold Resistance 1 and 2." It should work both ways, just devolve the trasmissions symptoms you don't need and get the other ones.

To get China nuked you have to do ALMOST the same things described before for Russia. You must follow the guide for Russian achievement except for these two differences.
Start in USA and evolve the same abilities. But in the transmission tree evolve ONLY Birds 1 - 2. This will make Spalin nuke China instead of Russia. So when Spalin becomes President DON'T EVOLVE Cold Resistance 1 - 2! (however, if necessary, evolve these 2 abilities but devolve when you infected everybody in the world)

Some people told me that this kind of run can be a little harder than before.

I did some testing and found out that the cure progress is faster. To counter this problem my advice is to kill people faster using symptoms like "coma" and "systemic infection" a lot early. If you get a pop-up saying "scientists have better understanding of *symptom*" then don't evolve that symptom because it will speed up the cure. For example in one of my tries scientists had better understanding of tumours, so i evolved tumours only to pick systemic infection then i devolved tumours right away.

During this process always look at the US population bar. You should get Spalin elected around 50 to 60% cure and around 40% people alive in US. Devolving symptoms doesn't cost anything (the game will in fact restore some DNA points when devolving).

Remember that, in the last stages of the run, you don't need any transmission perk so feel free to devolve Air 1-2 and Water 1 if DNA is needed.

Remember (when you start the killing phase) to evolve minor symptoms while you wait for Spalin elected (so scientist don't get the genome fully sequenced) and also that symptoms like Coma, Paralisys and Insanity will slow down the cure.

If iCure gets released, evolve "rash" and "sweating".

Last tip is: always save your game.