I'm no scientist. I'm not even the closest thing we have to a scientist here in our community, but I'll try to explain. It began deep in the ocean; experts said maybe it even started in several locations. Zooplankton, those tiny organisms that comprise the base of the aquatic food chain--they adapted. Due to environmental factors (climate change, dwindling predator populations, and chemical contaminants leaked into oceans were all suggested sources, but nothing was confirmed before the panic started.) many species of zooplankton drifted deeper into the seas and formed a symbiotic relationship with the decaying bodies at shipwreck sites. In a sense, they "learned" to reanimate dead human flesh to feed themselves.
The new species bloomed into nomadic swarms and, eventually, contaminated detritus washed up on shores world-wide. Stray body parts, a foot in a boot on the Washington coast, a thumb in Sydney, a whole head in Shanghai, were the harbingers. Ominous, but not clear indications of the impending catastrophe. Symptoms in living people varied wildly, apparently depending on which species had overtaken the body. By the time the Center for Disease Control discovered living human flesh was so vulnerable to the ravages of mutated zooplankton, it was too late.
When we, the survivors, arrived here at the Point Defiance Zoo, we went to great lengths—insane lengths really—to protect ourselves from one another. No one touched each other or shared utensils and we used the zoo's most corrosive, pungent disinfectant on our hands, our faces, and even our clothes and hair. So far, no one is showing any signs. So far.