Choose Pirate Plague, Shutdown Everything or Volcano Ash scenario whatever you need.
Genes: Harvester + Socially Awkward Bat + Teracyte + Extremophile + Mad Scientist
Normal Difficulty
Start in Saudi Arabia

With your starting DNA do:
Symptoms: Shadow Blessing (0)
Vampires: Blood Rage (10) + Blood Gift (4) + Dark Cloud (6)
Start Blood Rage in Saudi Arabia to collect DNA
Go for Shadow Trail (8) + Corrupted Air (10) to raise infection
Then go for Air 1 (13) (Water 1 in Volcano Ash) + Theriantrophy (8) and fly to India
While flying to India evolve Air 2 (12) (or Water 2 in Volcano Ash)

- Save Point -

While start consuming India follow symptom path to Shadow Slaves:
Nocturnal (1) + Anaemia (1) + Pallor (5) + Weeping Sores (3) + Hyperdontia (8) + Jugular Bite (14) + Shadow Slaves (17)

- Save Point -

Templars and Labs will arise soon, so its time to prepare for them:
Adrenal Surge (13) + Dark Infiltration (21) + Dark Ritual 1 (12)
India should be almost infected now, so fly to China and go for Travel Speed 1 (17)

- Save Point -

Bases are spawning. Look for the right outermost base and head to it. During flight you should have DNA and time to evolve Vampiric Awakening (19)

Once the right outer most base is destroyed, go from right to left and infect untouched or low infected countries (isles at best) on your way to the next base. Don't stay too long in intermediate countries, max. 5 days is enough for infection boost and a short healing.

If a second vampire appears, start travelling with him too and start another awakening asap (20). If you are lucky, he spawns on the left side of the world speeding things up, but dont worry if not.

If labs spawn on your way, take them down but dont leave your path too much for them yet until all Templars are destroyed.

While travelling and hunting bases, evolve Shadow Blades (34) + Dark Ritual 2 (25) + Travel Speed 2 (24)

If the third vampire awakens, you can use him to focus on labs now. Always infect isles and countries on your way.

While still fighting, evolve Demonic Fury (49) + Muscular Hypotrophy (17) + Masticatory Tension (18)

You can also evolve Dark Pustules (17) + Hypersensitivity (18) + Malignant Pigmentation (24) + Latent Adaptation (38) to slow down cure now.

You should have killed all bases if nearly 1 year is over.

- Save Point -

Evolve Lair (15) and create one in whatever countries your vampires are (should be 3).

Now hop from country to country and infect them to almost 90% before going to the next. Check infection map may help to find too healthy spots. Take remaining and spawning labs down ASAP.

Use DNA to evolve remaining symptoms and transmissions as you like, but don't go for lethality as we are enslaving the world.

Wealthy countries are slowest to infect so they may be the last countries your vampires are until you won the game. Normally i end up with all 3 in USA and Canada.

You should have enslaved the world in under 500 days and under 50% cure which gives you 3 biohazards.

It may be close so try to do good micro management and don't run the game in turbo mode. Use Space to pause helps even more.

Good Luck