The incubation period varies from 4 to 21 days until the nonspecific prodrome develops. Within hours or days after initial presentation, the clinical condition rapidly deteriorates, which results from the affinity for the vascular system of the virus. Increased vascular permeability leads to flushing, petechial hemorrhages, mucus membrane hemorrhage, and shock, often with neurological, pulmonary, or hepatic involvement [64] .