Health officials at London's Heathrow Airport have begun screening travelers from West Africa for Ebola.
But passenger Clive Paterson, who's been making a film about Ebola in Liberia, says he's surprised it's not compulsory.
(SOUNDBITE) (English) DOCUMENTARY MAKER, CLIVE PATERSON, SAYING:
"I would've thought if you're coming from a country like Liberia that you just have to be screened. It just seems to make more sense if you're going to go to this effort anyway."
The current outbreak of the virus is the worst on record and has already killed more than 4,000 people -- mostly in Liberia, Sierra Leone and Guinea.
Some have raised doubts about the effectiveness of border screening, since an infected person may not immediately show symptoms.
But Paul Cosford, who's the director of Public Health England, says he believes it will help.
(SOUNDBITE) (English) DIRECTOR OF PUBLIC HEALTH ENGLAND, PAUL COSFORD, SAYING:
"Obviously, this is a very new
