[Name] The Plague [Source] Mass Effect 2 [Symptoms] 
The Plague is a virus possibly created by the Collectors which infects all species except humans and vorcha, with the latter being resistant to any infection, and the former being immediately blamed for the spread of the plague and hunted down by local non-human criminals. It causes horrible sores, a bad cough and coughing up blood, as a result of rapid mutations to the respiratory systems. It was being spread through the ventilation system of the slums of Omega by the vorcha under orders of the Collectors but was stopped by Shepard and doctor Mordin Solus, since Omega has no authorities whatsoever and the affected area was simply sealed until everyone would die.