Updated

The number of deaths caused by Ebola has slowed dramatically in Guinea and the outbreak is nearly under control, the country's health ministry said on Tuesday.

The spread of Ebola from a remote corner of Guinea to the capital and into neighboring Liberia has killed about 130 people and spread panic across West African nations struggling with weak healthcare systems and porous borders.

While Guinea claimed progress in containing the virus, U.S. experts opened a lab for testing for Ebola in Liberia and Gambia stepped up travel restrictions, banning in-bound flights from collecting passengers in Guinea, Liberia and Sierra Leone.

"The number of new cases have fallen rapidly," said Rafi Diallo, a spokesman for Guinea's health ministry, who gave the latest toll of 106 dead in Guinea from 159 confirmed and suspected cases of Ebola since the outbreak began in February.

Diallo said the new cases being monitored were all people who had been in contact with those who had fallen ill but were not themselves unwell.

"Once we no longer have any new cases ... we can say that it is totally under control," he added.

The World Health Organization (WHO) said earlier this month that it would take two to four months to contain the Ebola outbreak, which is said had been one of the most challenging it had ever faced.

There is no vaccine or cure for Ebola, a hemorrhagic fever with a fatality rate of up to 90 percent.

However, Diallo said Guinea had recorded 37 cases of people recovering from the disease.

The WHO has said that just under 400 people were still being observed after being identified as potential Ebola contacts. Tracing potential cases in Conakry, the sprawling capital that is home to 2 million people, was tricky, it says.

Meanwhile, the U.S. Department of Defense on Monday opened a laboratory on the outskirts of Monrovia to test the rising number of samples of suspected cases in Liberia. It will eliminate the need to send samples overland into Guinea's remote southeast, where the disease was first confirmed and tests from Liberia are now being carried out, officials said.

Liberia's health ministry has recorded at least 13 deaths from 26 confirmed and suspected cases of Ebola. At least two of the dead were health workers, highlighting the need for experts to advise local staff on how to operate in the crisis.

Ebola cases in Liberia were first found near the border with Guinea but have been nearing the capital, Monrovia.

Samples tested in Mali, Ghana and Sierra Leone have been negative so far. But they have imposed restrictions ranging from basic health checks at airports to Dakar's completely shutting the land border between Senegal and Guinea.

Gambia on April 10 banned Banjul-bound aircraft from picking up passengers in Guinea, Liberia and Sierra Leone, according to a letter from the transport ministry seen by Reuters.