Truffula flu starts with symptoms of influenza, the first stage is coughing, fevers, chills, sore throats, etc. It’s air born at this stage and can be spread by harsh coughing. This gives it the ability to spread from animals to people. It also has a Cytomegalovirus mutation, which makes it attach to DNA. This means, like with One-ler and Ted, that the parasitic effect lays dormant in their bodies until activated by something like high stress or time. Dementia starts to happen with heightened fevers and a blood-brain barrier created by the JC virus mutation. This is generally spread by water, and so is the flu. It spreads much slower by water than it does air, because it passes through the digestive tracts and, sometimes, people won’t get infected at all this way because stomach acid destroys the virus.
The third stage is when the Staphylococci gene kicks in, which causes boils, swollen lymphnodes, and fatigue. The pus inside the boils are filled with a bioluminescent bacteria that creates luciferin and luciferase that reacts with the oxygen making the bacteria glow yellow. This could also become green, blue, and red due to variations or mutations in the genes. When the boils start to spread and immbed themselves deeper into the body, the bacteria can be taken into the blood stream and spread to other parts of the body—like open wounds, the heart, lungs, liver, and brain. This makes cutting off the infected limb useless.
Last, right before the victim dies, Huntington’s mutation starts. This makes the body move and react, with the bacteria providing just enough oxygen to the brain to make it continue to want it’s other necessities; like food. This is why the body is technically ‘dead’ because the heart, lungs, liver, and other organs stop working but, because the brain is being fed oxygen by the bacteria, it still survives creating the impulse for food and retaining the knowledge of walking and grabbing. However, opening doors, running, thinking, and other more complex actions are impossible.
The bacteria also creates oxygen for the muscles to allow movement, sometimes even replacing the muscle cells themselves so that legs, fingers, arms, etc. contract and allow for movement. Rigor mortis, however, would have settled in, making it incredibly difficult.