An isolation unit for Ebola victims in Liberia's capital, Monrovia, is overrun with cases and health workers are being forced to treat up to 20 new patients in their homes, government officials said Wednesday.

Protests by the local community against the construction of a new isolation unit at Elwa Hospital have ended, said Tolbert Nyenswah, an assistant minister of health, but patients with Ebola symptoms will have to wait at home until work is finished.

West Africa is battling the worst Ebola outbreak on record, with 672 people believed to have died in Liberia, Guinea and Sierra Leone since the epidemic began in February, according to the World Health Organization.

"The staff here are overwhelmed. This is a humanitarian crisis in Liberia," Nyenswah told Reuters by telephone. "People are being given care at their homes until we can move them to the new unit."

Nyenswah said the suspected patients were being treated by trained medical staff with full protective gear, but it would take at least 24 to 36 hours to build the new unit.

Initial resistance to building a new isolation unit highlighted the fear and mistrust health workers have faced across West Africa as they battle the outbreak, which has strained the region's weak health systems.

Dozens of local health workers have died treating patients and two Americans working for Samaritan's Purse, a U.S. charity operating in Liberia, were infected over the past week.

Samaritan's Purse said on Wednesday that Kent Brantly, a doctor working for Samaritan's Purse, and Nancy Writebol, a colleague who was also volunteering in Liberia, had shown a slight improvement but were still in serious condition.

The organization said that it was withdrawing nonessential staff from the country because of instability and security issues.