...radiation sickness following exposure to nuclear blast fall-out...
At first the vomiting and diarrhoea was thought to be dysentery and there were attempts amid the devastation to introduce some sort of quarantine to contain a possible outbreak.
Petechiae also appeared on limbs and pressure points. Large ecchymoses developed where needles had been injected. Wounds never healed, they just broke and bled. And there was sudden hair loss.
The petechiae in particular became an obsession, a mark of death to those affected...