Kraal virus
From Tardis Wiki, the free Doctor Who reference
The Kraal Virus was a virus created the Kraal Styggron. It was created to kill off the Humans of Earth for the Kraal. It would kill of all the Humans in three weeks, and then disappear, allowing the Kraal to conquer Earth without opposition. The virus can be transmitted by touch or by ingestion, but it can't travel by air. This meant the Kraal had to rely on their androids to transport the virus.
