Marburg and virulent Ebola viruses are maintained in hosts that are rare and have little contact with humans or do not readily
transmit virus. Bats (particularly solitary microchiropteran species) are leading contenders as reservoir hosts. Virus transfer
to humans occurs by contact with the primary reservoir or via an intermediate animal that acquired infection from the reservoir
and is, in turn, hunted by humans. An interesting possibility is that filoviruses may be arthropod or plant viruses, with
non—blood-feeding arthropods transmitting the virus to intermediate hosts or humans during oral ingestion or envenomation.
Paradoxically, in Africa, Ebola virus disease has high lethality and high seroprevalence as determined by the IFA test. If
the seroreactivity is confirmed by more specific tests, then the Ebola virus serogroup in Africa probably contains an antigenically
cross-reactive, enzootic, nonpathogenic agent(s). Such viruses may have separate life cycles or may give rise to virulent
strains by mutation.
"TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected."
