* Thrax is short for 'Anthrax', a lethal disease who's main symptom is a terrible, deadly fever. Despite those two strong similarities, Thrax shares no other similarities with the Anthrax disease and is in fact not an Anthrax virus, and is most likely a fictitous disease. *The song Thrax is humming is called 'Fever'. Thrax is short for 'Anthrax', a lethal disease who's main symptom is a terrible, deadly fever. Despite those two strong similarities, Thrax shares no other similarities with the Anthrax disease and is in fact not an Anthrax virus, and is most likely a fictitous disease. *The song Thrax is humming is called 'Fever'.