Ebola virus particles (red) budding from an infected host cell. (National Institute of Allergy and Infectious Diseases)

2 June 2026

By Betty Zou

On May 17, 2026, the World Health Organization declared the ongoing Ebola outbreak in the Democratic Republic of Congo a public health emergency of international concern.

The disease is caused by a family of Ebola viruses and transmitted through direct contact with bodily fluids. Early symptoms include the sudden onset of fever, fatigue, muscle pain and malaise, and can progress to vomiting, diarrhoea, severe bleeding and impaired kidney and liver function.

As of May 29, there have been approximately 1,000 suspected cases of Ebola and 270 suspected deaths reported in the DRC and neighbouring Uganda, but officials expect the numbers to rise as testing efforts expand.

Robert Fowler is a critical care physician at Sunnybrook Health Sciences Centre and a professor of medicine at the University of Toronto’s Temerty Faculty of Medicine. He is also the director of the interdepartmental division of critical care medicine at U of T and has previously served as a consultant with the WHO on the frontlines of the Ebola outbreaks in West Africa in 2014 and the DRC in 2018 and a Marburg virus outbreak in Rwanda in 2024.

Writer Betty Zou spoke with Fowler, who is also a member of the Emerging & Pandemic Infections Consortium, about the ongoing outbreak, lessons learned from previous epidemics and how prepared we are to respond today.

How worried are you about the current situation?

This is shaping up to be a particularly difficult Ebola outbreak for a number of reasons. Foundationally, it’s challenging because it’s happening in a part of the world that doesn’t have a lot of resources for a robust public health and clinical health care system. It’s also an area that has experienced a lot of conflict and migration over the last years.

Another reason this outbreak is particularly challenging is because this species of Ebola, Bundibugyo, isn’t as easily diagnosed with the currently used laboratory tests. The initial samples tested negative for the more common Zaire species of Ebola, which created a lot of uncertainty about who had the disease and should be isolated. This allowed for a period of non-detection and probable spread of the virus, so we’re catching the outbreak at a much later time point than we usually would.

How is the Bundibugyo species different from the Zaire species that we’ve typically seen in past outbreaks? How does that affect our approach to managing the outbreak?

Bundibugyo is a less common cause of Ebola virus disease. There have only been now a few outbreaks with the Bundibugyo species and therefore, we just don’t know quite as much about it. However, the mode of transmission and the clinical characteristics of patients who get infected are quite similar to the Zaire species. Based upon the limited outbreak experience, the mortality for this species is estimated at somewhere between 30 and 50 per cent, which is less than historical outbreaks of Ebola Zaire.

So far, there’s no vaccine that is known to be effective against the Bundibugyo species. There may be some cross protection from the Zaire vaccines, but there’s no knowledge about that yet. There’s also not yet an effective, specific treatment beyond supportive care. In both the West African outbreak of 2014 and in the DRC outbreak of 2018, monoclonal antibodies specific to the Zaire species were found to be quite effective at lowering mortality. We don’t have any of those antibodies created yet for the Bundibugyo species of Ebola. That said, one of the things we learned pretty well during previous outbreaks was that if you can deliver high-quality supportive care to people, the mortality rate of Ebola Zaire drops from 70 to 80 per cent down to 18 or 19 per cent.

What threat does this outbreak pose to public health? Is there a risk of this becoming a larger, more widespread epidemic?

I think there’s a substantial risk over the coming weeks and months that, in the affected areas, there is under-detection and more spread than people have realized thus far. In terms of spread beyond the region, what we’ve seen with past outbreaks is that there is a relatively small risk compared to other illnesses that may be spread by droplets or aerosols.

What is needed to get this outbreak under control?

Number one, having diagnostic testing capacity on the ground. This is limited right now and they’re having to request support from international partners and nongovernment organization (NGOs) to get more diagnostic testing into the area. Then, being able to do screening and contact tracing of cases is super important, but that’s been hampered by limited diagnostic testing. All the principles of outbreak management that rely upon public health measures — testing, screening, contact tracing, community awareness around best practices — are so important and will ultimately help to control the outbreak more than anything that we would do in a hospital setting, but it’s going to take a while.

A lot has changed since the last major Ebola outbreak in 2018. Are we in a better place to respond to these types of outbreaks or are we worse off?

I think both of those things are true. In one way, we’ve had a lot of experience with health-care systems around the world responding to outbreaks and a pandemic like COVID-19. I think our infection prevention control practices in health care and in the community are much, much better than they were a decade ago.

Yet in the region where this outbreak is happening right now, they are worse off than they were a few years ago. There is typically a lot of support from international partners to shore up resources in areas of the world that are prone to these outbreaks, yet don’t have the capacity to deal with them. Over the last couple of years, there’s been a huge drop off in international funding and that has had real consequences. For example, in access to diagnostic testing that helps detect these outbreaks and to personal protective equipment and other resources that people might need in hospitals to care for patients.

What is Canada’s role in helping to respond to outbreaks like this one?

Canada has had an outsized role in responding to viral hemorrhagic fever outbreaks over the last few decades. The National Microbiology Laboratory in Winnipeg developed both Ebola Zaire vaccines and medical countermeasures, particularly the antibody treatments, that were world firsts and used in the 2014 West African outbreak. The expertise in diagnostic testing capacity at the Public Health Agency of Canada and National Microbiology Lab have been deployed in many outbreaks before. There are always Canadians who are willing to help out in the region when there’s a need — I see that when I’m there. There’s also a need for countries like Canada to step up with funding and support for the work that’s done internationally by member states and groups like the WHO.

Are we ready to respond locally if Ebola is detected in Ontario?

We’ve never had a patient with Ebola in Canada. If we were to have an actual case, then we would lean on particular places that are designated to help provide that care. Toronto Western Hospital has been tapped as a provincial resource for caring for patients with high consequence pathogens, such as hantavirus and Ebola. The systems are in place there to make sure that people are practiced and can care for patients with meticulous infection prevention control measures and have a way to do diagnostic testing safely. But all hospitals need to be prepared to screen patients and to provide initial effective treatments for the more common conditions that people have when coming from Ebola-endemic areas, such as malaria, infectious gastroenteritis and bacterial sepsis. All these conditions need prompt care while we rule out other causes like Ebola.