Ebola-Reston
This variant of Ebola was first identified in cynomolgus monkeys
(crab-eating macaques) imported from the Philippines to the
Hazelton Laboratories in Virginia, USA in late 1989. This virus
was discovered during the investigation of an extensive mortality
event involving these monkeys, which was probably primarily
caused by a co-infection with simian haemorrhagic fever virus
(SHFV).
Further investigation showed that this new variant of the Ebola
filovirus family was unlike previously known Ebola strains in that,
although it caused disease and mortality in monkeys, it only
caused subclinical infections in humans exposed to the virus.
Secondly, this virus was able to be transmitted via the respiratory
route through the production of infectious aerosols by viraemic
monkeys.
In 1990 and 1993, investigations lead by the CDC Special
Pathogens Branch revealed a low level of seropositive monkeys
being imported from the Philippines and Indonesia, but field
trips to these locations failed to isolate the virus from animals
tested 3,5