Filoviruses are enveloped, nonsegmented negative-stranded RNA viruses. The
two species, Marburg and Ebola virus, are serologically, biochemically, and
genetically distinct. Marburg virus was first isolated during an outbreak
in Europe in 1967, and Ebola virus emerged in 1976 as the causative agent o
f two simultaneous outbreaks in southern Sudan and northern Zaire. Although
the main route of infection is known to be person-to-person transmission b
y intimate contact, the natural reservoir for filoviruses still remains a m
ystery.