Red-Eye

Description
WARNING: SPOILERS FOR THE LAST WILD

The red-eye, or berry-eye, as called by the animals, is a virus that infects and kills off all animals alive in The Last Wild. It cannot affect humans, but may easily pass on to one creature to another, causing them to feel sick and dizzy, before dying with their eyes turned completely red.

This virus also does not affect varmints like moths and cockroaches, though at Spectrum Hall, the children and people there are warned never to touch varmints, in case the virus might be somehow lingering on them.

After Kester realizes that the animals want him to find a cure for them, he tells them that his father, the "infamous" Professor Dawson Jaynes, might already have the cure to the flu. This hopeful idea sends them off, and so continues the story of The Last Wild.

Impact on humans
The red-eye kills off animals, which therefore cuts the humans off with their source of food. With animals gone, the crops, too, began to die out. Soon, humans were left eating rations, and when that finished, they consumed a "goop-like substance" called Formul-A (pronounced for - mew - lay).

Formul-A is a pinkish, thick substance, and Kester feels that it tastes like prawn-cocktail crisps. After the animals disappeared from the red-eye and the rations and crops too were gone, a food company called Factorium (Facto for short) produced Formul-A, to replace normal food. Being the biggest (and possibly the only, according to Kester) food company in the world, they run everything - they produce the (maybe) only man-made food left in the entire world safe for humans to eat.

Symptoms
According to Kester's description, the red-eye is a virus in which the bodies and brains of infected animals "turn into mush" and, just before they die, their eyes burn bright red "like they (are) on fire inside".

The red-eye begins with the infected animal begins to feel hot inside, like a fire burning within its body. It will begin to feel tired and dizzy, though no amount of rest will help, as mentioned by the stag, Wildness.

Slowly, as it begins to die, it will feel a burning pain behind their eyeballs as the eyes turn into a bright red, before it finally passes on.

Other mention symptoms include the fur or feather of the animal falling off and the skin turning a bit yellow, as well as stomach sickness.

Cure
WARNING: SPOILERS FOR THE NEAR END OF THE LAST WILD

At first, to the animals, there seemed to be no cure for this deadly flu. Wildness mentioned to Kester that "no water, no leaf, no amount of rest can bring relief".

But after Kester and Polly and the animals find Professor Jaynes, it is revealed that Professor Jaynes possessed a sample of the cure - a trial drug. Kester and Polly help him continue his research and experimenting, and soon they come up with a cure for the red-eye, in the form of gel sticks that can be chewed, licked, pecked, or even swallowed whole.

They then name the drug Laura II, in memory of Kester's dead mother, whose name was Laura.