Washington- New US rules requiring air passengers from the three West African countries worst hit by Ebola to travel via one of five airports are coming into effect, US media reported on Wednesday.

Travelers from Sierra Leone, Liberia or Guinea must now arrive at O'Hare in Chicago, JFK, Newark, Washington's Dulles or Atlanta, where they will undergo enhanced screening. The World Health Organization is due to convene an emergency meeting later.The current outbreak of the virus has already killed more than 4,500 people.

Most of the deaths have been in Guinea, Liberia and Sierra Leone. Travelers from these countries will have their temperatures checked as part of screening programs, despite experts warning such moves are unlikely to have an impact.

The new security measures come as public concern grows in the US, where three people have been infected and one person has died from the virus.

The precautions stop short of the travel ban sought by some US Congress members. Meanwhile, the family of Thomas Eric Duncan, a Liberian man who died from Ebola in the US earlier this month, say hospital officials have refused to release information about his treatment, the Associated Press reports.

It comes amid claims that staff at Texas Health Presbyterian hospital mishandled the case."None of the procedures were discussed with the family,'' his nephew, Josephus Weeks, told local media.