Ebola crisis: Fresh UK deployment to Sierra Leone
About 100 soldiers from the Royal Army Medical Corps are travelling to Sierra Leone as part of the UK's efforts to tackle the Ebola outbreak.
International Development Secretary Justine Greening will join the medics to see how Britain's £125m aid package is helping to combat the deadly virus.
Her visit to West Africa comes as the UN said a third member of its staff in Sierra Leone had died from the disease.
In the UK, Gatwick has begun screening air passengers from at-risk countries.
The outbreak has killed more than 4,500 people in West Africa, with Liberia, Guinea, and Sierra Leone the three worst-affected countries.
On Monday, the World Health Organization (WHO) declared Nigeria - West Africa's most populous nation - officially free of the virus after six weeks with no new cases. It comes after WHO officially declared Senegal Ebola-free on Friday.
Cabinet minister Ms Greening left RAF Brize Norton in Oxfordshire on Tuesday morning with the medics from Catterick-based 35 Squadron, 5 Armoured Medical Regiment and the Royal Army Medical Corps.
They will staff an Ebola training academy alongside some 90 personnel from 22 Field Hospital who left for Sierra Leone last week.
Ms Greening will visit the academy and the site of a 92-bed treatment facility in Kerry Town, which is in the final stages of construction.
She said: "Halting the disease in West Africa is the most effective way of preventing Ebola infecting people here in the UK.
"That is why we are providing 700 treatment beds in Sierra Leone, sending vital supplies such as chlorine and protective clothing, and training hundreds of health workers.
"I look forward to seeing for myself how British army medics and engineers, as well as our humanitarian and health workers, are spearheading the UK's efforts to contain and ultimately defeat Ebola."
The UK is leading the international response to the disease in Sierra Leone, where it has pledged a £125m aid package.
In all, Britain is deploying 750 military personnel, including the Royal Navy's casualty ship RFA Argus.
European countries have committed more than 500m euros (£400m; $600m) - but the UK is pressing for that amount to be doubled.
The UN has said the outbreak is the most serious health emergency of modern times.
BBC international development correspondent Mark Doyle said the British contribution was significant, but it has come "very late" despite warnings from medical charities as early as April.
Ghana's President John Mahama, meanwhile, has said vital supplies and resources to tackle Ebola are now beginning to reach the three worst-hit West African countries.
Mr Mahama told the BBC that the World Food Programme was airlifting humanitarian aid to Liberia, Sierra Leone and Guinea.
In the UK, screening for passengers from affected countries started at Gatwick Airport on Tuesday, beginning at the north terminal and to be rolled out to the south terminal by the end of this week.
It comes after Heathrow began screening last week. Screening for Eurostar passengers arriving at London's St Pancras station, along with passengers at Birmingham and Manchester airports, is expected to start soon.
UK Ebola mission in Sierra Leone
Pledged by UK to help fight disease
780 British health staff volunteers helping to cope with the crisis
700 Hospital beds supported by UK - tripling Sierra Leone's capacity
750 Military staff to help construct treatment centre and other facilities
100 Beds on board medical ship RFA Argus being deployed to region
Ebola virus disease (EVD)
- Symptoms include high fever, bleeding and central nervous system damage
- Spread by body fluids, such as blood and saliva
- Fatality rate can reach 90% - but current outbreak has mortality rate of about 70%
- Incubation period is two to 21 days
- There is no proven vaccine or cure
- Supportive care such as rehydrating patients who have diarrhoea and vomiting can help recovery
- Fruit bats, a delicacy for some West Africans, are considered to be virus's natural host