GENEVA, Switzerland (AFP) — The risk from a deadly Ebola outbreak in central Africa remains high, but remains low globally, the World Health Organization said Wednesday, adding that the virus had likely been spreading for months.

The outbreak of the highly contagious haemorrhagic fever was declared in eastern Democratic Republic of Congo last Friday.

Ebola has killed more than 15,000 people in Africa in the past half-century, and the UN health agency has declared the latest surge an international health emergency.

The 17th Ebola outbreak to hit the DRC is already suspected of having caused 139 deaths from around 600 probable cases.

“We expect those numbers to keep increasing, given the amount of time the virus was circulating before the outbreak was detected,” WHO chief Tedros Adhanom Ghebreyesus told reporters.

On Sunday, Tedros declared the outbreak a so-called public health emergency of international concern — the second-highest level of alarm under the legally-binding International Health Regulations (IHR).

But, he said Wednesday, it had been determined “the situation was not a pandemic emergency”.

Following a meeting of the WHO’s emergency committee, he said the agency “assesses the risk of the epidemic as high at the national and regional levels, and low at the global level”.

The European Commission in Brussels insisted that the risk of infection in the EU was “very low” and that “there is no indication” that Europeans should take specific measures.

Ebola is a deadly viral disease spread through direct contact with bodily fluids. It can cause severe bleeding and organ failure.

The WHO has highlighted the complexity of detecting and responding to the current outbreak, which has been spreading in hard-to-reach areas of the DRC’s conflict-torn Ituri province.

Complicating things further, the less common Bundibugyo species behind the outbreak does not show up on tests for the more common Zaire strain of Ebola.

And with no vaccines or specific treatment available for Bundibugyo, measures to curb its spread are limited.

The WHO has said it is examining whether any candidate vaccines or treatments could be used to rein in the outbreak.

Anais Legand, WHO technical officer on viral haemorrhagic fevers, stressed though that the organisation’s priority was to “cut the transmission chain” through contact-tracing, isolation and care for all suspected and confirmed cases.

But at a hospital near Ituri’s main city Bunia, equipment to isolate suspected cases of Ebola, and full protective gear for nurses has only just begun arriving.

“We dig graves and bury dead people without gloves or any protection,” said Salama Bamunoba, a youth organisation representative.

With the recent cases largely concentrated in remote areas, few samples have been laboratory-tested and figures are based mostly on suspected cases.

So far, 51 cases have been confirmed in the DRC’s eastern provinces of Ituri and North Kivu, while two cases have been confirmed in the Ugandan capital Kampala, including one death.

A US national working in the DRC has also been confirmed positive and transferred to Germany.

WHO’s emergency alert and response director Abdi Rahman Mahamud stressed Wednesday that “all contacts, all cases should not travel”.

Washington announced Tuesday it was screening air passengers from outbreak-hit areas and temporarily suspending visa services, although a State Department official said the DRC football team would be allowed to travel to the United States for the World Cup.

And Bahrain announced a 30-day ban on visitors from the DRC, South Sudan and Uganda.

WHO experts said investigations were under way into the origins of the current outbreak.

The first identified case was a nurse, who went to a health centre on April 24 in the city of Bunia, the capital of Ituri province.

But the epicentre of the outbreak is about 90 kilometres (56 miles) away, in Mongbwalu, which suggests the outbreak originated there and that the cases then spread.

The WHO has said it was alerted to the emergence of a highly lethal disease on May 5, with the first positive Ebola test on May 15.

“Given the scale, we are thinking that it has started probably a couple of months ago,” Legand said.

Tedros meanwhile hit back at criticism over the response time from the United States, which under President Donald Trump has announced its withdrawal from the WHO.

On Tuesday, US Secretary of State Marco Rubio charged that the WHO “was a little late to identify this thing”.

Asked about the US criticism, Tedros said that could stem “from lack of understanding of how IHR work, and the responsibilities of WHO”.

“We don’t replace the countries’ work, we only support them.”