Geneva, August 19 (RHC)-- The World Health Organization (WHO) has urged Ebola-affected nations to begin exit screening all people departing international airports, seaports and ground crossings.

The UN health agency announced on Monday that even countries unaffected by the outbreak in West Africa must strengthen their ability to detect and contain new cases. The WHO says: "Transmission requires direct contact with blood, secretions, organs or other body fluids of infected living or dead persons or animals, all unlikely exposures for the average traveler."

The WHO did not specify which countries should start screening travelers, but noted that the Ebola crisis involves transmission in Guinea, Liberia, Sierra Leone and Nigeria. The authorities in the four African countries have already begun examining people leaving for any symptoms.

According to the WHO, Ebola has already killed 1,145 people in West Africa: 413 in Liberia, 380 in Guinea, 348 in Sierra Leone and four in Nigeria. But some people from other parts of the world, including the U.S., have also contracted Ebola after visiting the West African nations.