British officials said Saturday that 16 reservists and 100 regular military personnel left on a morning flight from the Brize Norton military airbase.
Officials say Canadian military personnel are on the same flight.
They will take over a field hospital providing treatment to health care workers in Sierra Leone who have become infected with the often lethal virus.
The group has received special training in how to operate wearing protective gear.
Defence officials say Britain has roughly 800 military personnel in Sierra Leone. They are building facilities expected to provide 700 beds for treating people with the virus.
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