KINSHASA, Democratic Republic of Congo—Health workers in the Democratic Republic of Congo are scrambling to contain an outbreak of Ebola virus, which is suspected to have killed more than 200 people and risks spreading across international borders.

According to Congolese government figures released on Saturday, health workers have registered 867 suspected cases of Ebola and 204 deaths.

The Congolese government first declared an outbreak on May 15. Since then, confirmed and suspected cases have popped up across an area of Congo larger than the state of Florida.

Neighboring Uganda has also registered five confirmed Ebola cases.

On Friday, the World Health Organization raised its risk level for the disease at a national level to “very high.”

“The potential of this virus spreading rapidly is high, very high, and that changed the whole dynamic,” Abdirahman Mahamud, WHO director of health emergency alert and response operations, told reporters.

Ebola is a viral disease that causes vomiting, fever and sometimes bleeding. It can take weeks to show symptoms and is often fatal.

Congolese health workers, UN staff and aid organizations rapidly launched a large-scale response against the disease after an outbreak was confirmed.

But Ebola was likely spreading for weeks — if not months, according to some estimates — before health authorities noticed it. This late diagnosis and the now unknown number of people who are infected will severely complicate the response.

The first known case was of a nurse who presented symptoms on April 24, in the city of Bunia, in Ituri province, in eastern Congo.

According to an internal report by the Congolese health ministry, the nurse was buried in the gold-mining town of Mongbwalu, in Ituri.

The town had had a spate of unexplained deaths throughout April, including of four health workers who died in the space of a single week.

The report noted that there was “widespread panic among the population, fueled by rumors of supernatural causes” for the deaths.

Three Red Cross volunteers working in the region have also died from suspected Ebola after reportedly handling infected bodies, the organization said.

Delays in identifying the Ebola outbreak were caused in part by the rarer species of the virus that is circulating.

Congo has had 17 official Ebola outbreaks since 1979, with the majority of those caused by the Zaire species of the virus — for which there is a vaccine.

But the latest outbreak is caused by a much less-studied species named Bundibugyo, according to Congo’s National Institute for Biomedical Research.

‘The virus affects us all’

More than a week since the outbreak was declared, aid workers have started setting up Ebola treatment centers in eastern Congo.

But U.S. aid cuts are complicating the response, according to Congo’s Health Minister Roger Kamba, who called last week for increased funding in order to battle the disease.

“The virus knows no borders, it knows no race, it knows no tribe,” the minister told reporters in the capital Kinshasa. “The virus affects us all.”

Congo is one of the five poorest countries in the world, according to the World Bank, where more than 80 percent of people survive on $3 a day or less.

For health responders, tackling the disease is a huge undertaking. Much of eastern Congo is plagued by violent armed groups and road infrastructure is extremely poor.

Ituri, the epicenter of the outbreak, suffers regular massacres committed by notorious armed groups such as the Codeco, or the Islamic State-aligned ADF.

Outbreak hotspots such as the towns of Mongbwalu and Rwampara are also difficult to operate in.

Both are rough mining towns, where tens of thousands of people survive by digging for gold with crude tools. Living and working conditions for most people are cramped and unsanitary.Outsiders are also relatively rare in these remote areas. Health responders say one of their largest problems is a lack of community trust.

“Community reactions remain mixed,” Gabriela Arenas, Regional Operations Coordinator for the IFRC Africa Region, told reporters via video link from Nairobi.

“For some, the outbreak is real and they are actively seeking information on how to protect themselves. For others, suspicion and misinformation persist, with claims that Ebola is fabricated.”

Just twice in the last week, angry residents have attacked health clinics or treatment centers in Mongbwalu and Rwampara, in some cases setting fire to medical tents.

Risk of spread

Confirmed Ebola cases have also now been recorded in the provinces of North Kivu and South Kivu, large areas of which are governed by Rwanda-backed M23 rebels, which will further complicate the response.

There are also fears that the virus could spill over into other countries.

The economy of eastern Congo is inextricably linked with those of neighboring states such as Uganda, Rwanda and Burundi. And many of the region’s major cities lie on the edge of national borders.

Uganda, for example, shares a land border with Ituri, the epicenter of the outbreak.

It is now trying to contain its own smaller Ebola outbreak, after two Congolese infected with the virus traveled to the country.

Over the weekend, the Ugandan ministry of health announced that it had recorded three more Ebola cases — including of Ugandan nationals who had come into contact with the infected Congolese travelers.

Uganda has temporarily halted all flights to and from Congo and restricted crossings at its land borders to try to avoid the disease spreading.