The news – which has sparked fears that the deadly virus could spread further – comes as the World Health Organization (WHO) said there have been more new cases of Ebola infections in the past week than at any other time. The group had earlier warned that the disease was spreading faster than efforts to control it.

Over 3,000 cases of the virus have been reported so far in the largest Ebola outbreak ever recorded. The diseases’ spread to densely populated West African capitals has contributed to the speed of its transmission. And over 1,500 people have died of the hemorrhagic virus since it was first detected in Guinea in March.

The latest outbreak then spread to Liberia, Sierra Leone and Nigeria. The Democratic Republic of Congo reported a separate outbreak of Ebola Sunday that has killed at least 13 people.

Some airlines have canceled flights to affected countries as authorities attempt to stem the spread of the disease. As transport companies suspend services, cutting off the region, governments and economists have warned that the epidemic could crush the fragile economic gains made in Sierra Leone and Liberia after a decade of civil war in the 1990s.

African Development Bank chief Donald Kaberuka said on a visit to Sierra Leone that he had seen estimates of a reduction of up to 4 percent in gross domestic product due to Ebola.

“Revenues are down, foreign exchange levels are down, markets are not functioning, airlines are not coming in, projects are being canceled, business people have left – that is very, very damaging,” he said late Tuesday. “I understand the countries which are posing restrictions … but let us only do so based on medical evidence and not on political imperatives.”

WHO has repeatedly advised against such bans, warning they could lead to food and supply shortages. The health organization said Thursday that it believes the number of Ebola infections is underreported, and that the number of cases could reach as many as 20,000 before the outbreak is controlled.

Al Jazeera and wire services