The World Health Organisation on Thursday said 48 cases of Ebola have been confirmed in the Democratic Republic of Congo and 31 people have died.

"It has been two weeks since the government of the DRC declared an Ebola outbreak ...So far, 48 confirmed and probable cases have been reported, and 31 people have died," World Health Organisation chief Tedros Adhanom Ghebreyesus told reporters via video link from the WHO headquarters in Geneva.

The outbreak, the country's first in three years, was declared in early September.

Congo's dense tropical forests are a natural reservoir for the Ebola virus, which causes fever, body aches, and diarrhoea, and can linger in the body of survivors only to resurface years later.

The World Health Organisation on Sunday said it had begun vaccinating frontline health workers and contacts of people infected with the Ebola virus in Congo's Kasai Province, where an outbreak has been declared.

The WHO said an initial 400 doses of the Ervebo Ebola vaccine from the country's stockpile of 2,000 doses have been delivered to Bulape, which is the outbreak's epicentre.

The WHO has delivered more than 14 tonnes of essential medical supplies, deployed experts and set up an Ebola treatment centre with 16 patients currently being treated, Tedros said.

More than 900 contacts have been listed and are being followed up.

The first two patients to recover were discharged on Tuesday, he added.

The U.S. Centers for Disease Control and Prevention on Thursday issued a health advisory, to public health departments, clinical laboratories and healthcare workers on the Ebola outbreak in Congo.

Currently, no suspected, probable, or confirmed cases related to the outbreak have been reported in the United States or outside Congo, said the agency, adding "the risk of spread to the United States is considered low at this time."