What to know about Ebola outbreak after WHO sounds global alarm

Ebola is one of the deadliest diseases on Earth.

With a fatality rate as high as 90 per cent, it’s among a handful of illnesses so dangerous that governments consider them threats to national security. 

A new outbreak in north-eastern Democratic Republic of Congo, which has spread to neighbouring Uganda, has raised fears that the virus could prove harder to contain because it involves the rare Bundibugyo strain, for which there are no approved vaccines or antibody treatments.

On May 17, the World Health Organization declared the outbreak a “public health emergency of international concern”.

Congo has extensive experience responding to Ebola outbreaks. But years of conflict in the country’s east, weak infrastructure and growing strain on global health programmes after US aid cuts could complicate the response.

What is Ebola?

Ebola disease is caused by viruses belonging to the orthoebolavirus family, primarily found in sub-Saharan Africa. Six species have been identified, though only four are known to cause disease in humans.

Scientists believe Ebola spills over into humans through contact with infected animals, including chimpanzees, gorillas and bats.

It spreads between people through direct contact with bodily fluids from those infected or contaminated materials. Family caregivers and healthcare workers are often at highest risk during outbreaks.

Unlike airborne viruses such as the coronavirus that causes Covid-19, Ebola doesn’t spread easily through casual contact. Transmission generally requires close exposure to bodily fluids, particularly when patients are severely ill or have died.

Why is the Bundibugyo strain significant?

The current outbreak has been identified as Bundibugyo ebolavirus, a rare species first detected in western Uganda in 2007.

Only two previous Bundibugyo outbreaks have been recorded – in Uganda in 2007 and eastern Congo in 2012 – meaning scientists know far less about the virus than the more common and deadlier Zaire strain.

Most Ebola vaccines and antibody therapies were developed specifically against Zaire ebolavirus after the devastating 2013 to 2016 West African epidemic, which killed more than 11,000 people in the largest Ebola outbreak on record.

The virus spread beyond Guinea, Liberia and Sierra Leone into neighbouring countries and isolated cases appeared in Europe and the US.

That leaves fewer medical countermeasures available for Bundibugyo.

While doctors may still consider using antivirals such as Gilead Sciences’ remdesivir, there are no licensed vaccines or approved monoclonal antibody treatments specifically targeting the strain.

What’s worrying about this outbreak?

Health officials say the outbreak may have circulated undetected for weeks before it was identified.

The virus is spreading in Ituri province, a remote and conflict-affected part of eastern Congo more than 1,700km from Kinshasa. The area has poor roads, limited healthcare infrastructure and active armed groups.

The outbreak is centred around Mongbwalu, a gold-mining region where tens of thousands of workers move between remote camps and nearby trading hubs. Suspected infections have also been detected in Bunia, the provincial capital, which has a population of almost 700,000.

Frequent travel across borders with Uganda and South Sudan raises the risk of wider regional spread. Uganda has recorded a small number of infections among travellers from Congo.

What does the World Health Organization’s declaration mean?

The designation – known as a Public Health Emergency of International Concern, or PHEIC – is the World Health Organization’s highest formal alarm under international health law.

It’s used for extraordinary outbreaks that pose a cross-border public health risk and require a coordinated international response.

WHO has previously issued PHEIC declarations for Covid-19, mpox, polio and earlier Ebola outbreaks. The designation doesn’t mean the current outbreak is expected to become a global pandemic, but it is intended to mobilise funding, technical support and preparedness efforts.

WHO said countries should strengthen disease surveillance, laboratory testing, contact tracing, border screening and treatment preparedness, particularly in neighbouring states at risk of cross-border spread.

How well-equipped is Congo to respond to the outbreak?

Congo is considered one of the world’s most experienced countries in managing Ebola after confronting more than a dozen outbreaks since the virus was first identified near the Ebola River in 1976.

The country has built systems for rapid testing, contact tracing, ring vaccination and community engagement. Its last Ebola outbreak, declared over in December 2025, was contained within six weeks.

Still, repeated conflict in eastern Congo has weakened healthcare infrastructure and complicated outbreak responses in some regions.

Global health experts have also warned that cuts to US foreign aid and public health programmes could weaken disease surveillance and emergency response capacity in fragile states.

A study published in Science in May found the abrupt withdrawal of USAID funding was associated with increased conflict in heavily aid-dependent parts of Africa.

During previous outbreaks, the US provided funding and technical support through the Centers for Disease Control and Prevention and USAID, helping train epidemiologists, expand laboratory capacity and support vaccine deployment.

How does Ebola affect people?

Symptoms can begin suddenly and include fever, fatigue, muscle pain, headaches and sore throat, followed by vomiting, diarrhoea and, in some cases, internal or external bleeding.

The virus attacks the immune system and multiple organs, potentially causing shock, organ failure and death.

Some Ebola survivors develop long-term complications, including chronic pain, eye disease and neurological symptoms.

Researchers have also found that the virus can persist in immune-privileged sites such as the eyes, central nervous system and testes, where it may remain for months or years after recovery and, in rare cases, lead to sexual transmission or renewed outbreaks.

How is Ebola treated?

Early treatment improves survival chances.

Patients are typically given intravenous fluids and electrolytes to prevent dehydration, oxygen support, medications to stabilise blood pressure, and treatment for secondary infections and complications.

Two antibody therapies are approved for Zaire ebolavirus disease, but they haven’t been approved for Bundibugyo infections.

Is there an Ebola vaccine? 

The Ervebo vaccine is highly effective against the Zaire strain of Ebola and has been widely used in Congo during previous outbreaks through “ring vaccination” campaigns targeting contacts of infected people and front-line healthcare workers.

There are currently no widely approved vaccines for the Bundibugyo ebolavirus. BLOOMBERG