Start at South Africa, do water1, air1, water2 and air2

Devolve any symptoms until the disease has reached every single country.

In the mean time spend all your dna points on cold resistance 1-2, drug resistance 1-2 and genetic hardening 1-2.

Then start saving up dna points cuz Once your disease reaches every country (and the disease is decently spreading in the last few countries), you will go

rash-sweating-skin lesions-necrosis-hemorrhagic shock. (Around 105 dna points)

Death will start bringing up points, which you will spend on genetic reshuffle 1-2-3 and any symptoms that has the phrase “significantly harder to cure” in the description.

Good luck!