The United States will issue strict new guidelines telling American health workers to cover their skin and hair when dealing with Ebola patients, a top health official said on Sunday

The United States will issue strict new guidelines telling American health workers to cover their skin and hair when dealing with Ebola patients, a top health official said on Sunday, while some of the dozens of people being watched for possible exposure to the virus are expected to be cleared.

In Texas, a lab worker who spent much of a Caribbean holiday cruise in isolation tested negative for the deadly virus and left the Carnival Magic liner with other passengers after it docked at Galveston early on Sunday morning.

The new guidelines for healthcare workers and the precautions taken for the cruise passenger reflected widespread anxiety over Ebola in the United States, including calls from some lawmakers for a travel ban on West Africa.

The worst outbreak on record of the virus has killed more than 4,500 people, mostly in Liberia, Sierra Leone and Guinea.

Liberian President Ellen Johnson Sirleaf urged stronger international action to control the epidemic, saying on Sunday the disease was unleashing an economic catastrophe that will leave a "lost generation" of young West Africans.

Belgium announced on Sunday it would screen people arriving at its largest airport from West Africa for signs of fever. In Spain, the government said Teresa Romero, the nurse who contracted Ebola while caring for two infected priests, appeared to be free of the disease.

The new guidelines being developed by the U.S. Centers for Disease Control and Prevention would increase protection for medical workers caring for Ebola patients. The new measures were prompted by anxiety after two nurses were infected with the virus, which is spread by contact with bodily fluids of sick people and so makes health workers especially vulnerable.