Returned virus

The Returned virus scientifically appears to be a mutated form of the Spanish flu, possibly with a precursor virus harbored in birds. It's contagious as long as symptoms are present, but only Returns are susceptible to the virus.

The Bureau of Returns believes the virus originated in the 1900s, from a Return whose metabolism mutated it. They've lost 66 Returns to the virus and found there is a 23 percent mortality rate. Angela Forrester believes Returns should be left to infection and that it's "nature taking its course", the natural course or a Returned life cycle. However, she treats them despite the possibility of it being normal so the Bureau can collect all data possible about Returns.

Symptoms
Symptoms of the virus increase and become more persistent the more symptoms patients present.

Minor

 * Coughing, wheezing and trouble breathing
 * Fever

Chronic and fatal
Once patients start experiencing chronic symptoms of the virus, it spreads more rapidly. The last symptom is vanishing, though only Margaret Langston knows the cause of this. Thus, the symptoms likely get so bad that patients wish themselves away, thus "disappearing".
 * Fever
 * Cold chills and sweats
 * Coughing/spitting up blood
 * Not waking up
 * Fainting
 * Skin discoloration (blue) due to lack of oxygen in blood
 * Delirium from high fever
 * Bleeding from ears and nose

Treatment
The Bureau with which J. Martin Bellamy works formulated an experimental drug that eases the symptoms and delays the effects of the virus, but not a cure because the virus mutates too quickly. It can be taken via the arm or the hip.

Notable patients

 * Arthur Holmes
 * Mikey Enders
 * Rachael Braidwood
 * J. Martin Bellamy