As the Ebola virus spreads through West Africa, with cases now hitting three countries in addition to Guinea where the Ebola outbreak is centered, health authorities now fear that the virus could spread beyond African shores — and they are taking steps to make sure that doesn’t happen.

Guinea was a colony of France until 1958 and the French still provide medical, health and other aid to the country, and to other African countries that were once French territory. This week, French medical teams have taken up posts at Gbessia International Airport, the only such international airport in the Guinea, in the country’s capital of Conakry.

A swarming and largely poverty-stricken city of 2 million, Conakry has seen 16 Ebloa cases, even though it is located some 185 miles from the remote, forested area in the southeast where the Ebola virus first appeared in Guinea, and where the majority of cases are concentrated.

The French medical screeners at the airport in Conakry, from which flights depart to France as well as to other African countries, are checking travelers for fever and asking them to fill out forms listing any symptoms or health conditions they may have been experiencing.

Any traveler suspected of carrying the Ebola virus will be immediately quartantined.

“The aim is to prevent the spread of the disease and reassure the international community that arrangements are being made in Conakry to prevent the spread of the disease,” said Patrice Loua of Doctors of Africa, a medical aid group that has also been taking part in the airport screenings.

In the Philippines, the government there has initiated screenings of incoming airline passengers at airports in that country, in an attempt to keep the Ebola virus at bay.

The Philippines was the source on an Ebola virus outbreak that reached U.S. shores in 1989 — but that outbreak was confined to monkeys imported from the Philippines and held in a quarantine center in Reston, Virginia, outside of Washington D.C.

Imported monkeys must be quarantined for 30 days before being released to their destinations. The Reston monkeys had a strain of Ebola virus that had, at that time, never been seen. Apparently, human beings were immune to the strain, named Ebola Reston, because six people who came in contact with the monkeys were found to have contracted the new version of Ebola virus. But ultimately, none of the six got sick.

One troubling question remained, however.

How did Ebola virus, thought to be confined to the African continent, make its way across thousands of miles to Southeast Asia?