Ebola may have circulated undetected in Congo for months

The Democratic Republic of Congo officially declared the Ebola outbreak caused by the Bundibugyo variant on May 15. However, the first infections likely occurred much earlier.

Just how far back the start of the epidemic actually goes is still a matter of debate. But one thing is certain: The Congolese authorities did not respond in the best possible way. Several international organizations have highlighted delays in the initial response.

Congo is no stranger to crisis response: The country experiences Ebola outbreaks on a regular basis and has in the past been praised for its expertise in combating the disease.

Early warnings came from WHO and Africa CDC 

A good starting point for tracing the origins of the outbreak is the timeline provided by the World Health Organization (WHO) in collaboration with the Africa Centres for Disease Control and Prevention (Africa CDC).

According to their data, the first known case, identified retrospectively, was a health worker from Mongbwalu in northeastern Ituri Province. The person, sources said, developed symptoms characteristic of Ebola around April 24 or 25.

They died at a medical center in Bunia, the capital of Ituri. To date, 80% of all cases have been reported in the province.

It was not until May 5 that the WHO said  it had been informed of “an unknown disease with high mortality reported in the Mongbwalu Health Zone.” The global health body then issued its first warning.

Congo’s delayed response questioned as Ebola spread

Ten days later, on May 15, the Congolese government announced the Ebola outbreak. 

Tests conducted by the National Institute for Biomedical Research (INRB) in Kinshasa had confirmed the presence of the Bundibugyo ebolavirus.

Three days later, the Africa CDC raised concerns about the speed of Congo’s response.

About three weeks had passed between the onset of the first symptoms in the suspected index case and the laboratory confirmation — even though the fatality was a health worker.

“This significant delay (…) highlights a critically low initial index of clinical suspicion among local healthcare providers, which facilitated wider geographic spread prior to the initiation of containment efforts,” the Africa CDC concluded.

According to reports gathered by DW, residents of Mongbwalu had already reported suspicious deaths as early as the end of April.

“Several deaths were reported following high fevers, and the victims often showed traces of blood around various body orifices,” said Dieudonne Lossa Dekhana, the provincial coordinator for civil society in Ituri.

Red Cross reported ‘widespread’ public fear ‘since March 30’

There were other indications that Ebola was already circulating long before this first confirmed case emerged.

A May 16 report by the Red Cross of the Democratic Republic of the Congo stated: “Since March 30, 2026, there has been widespread fear among the population of the Mongbwalu Health Zone following a series of deaths.” 

Here, too, the symptoms matched those of Ebola: high fever, chest pain, severe exhaustion, persistent cough, nosebleeds, vomiting, loss of consciousness, a comatose state, and ultimately death.

The Red Cross report said the trigger was believed to have been the body of a Mongbwalu resident “who died and was placed in a coffin purchased in Bunia, which was then replaced by another in Mongbwalu.”

US researchers: February outbreak is plausible

The funeral that brought various people into direct contact with the body and the contaminated coffin is believed to have been the cause of a rising number of infections and deaths that were subsequently observed in Mongbwalu and Bunia.

But from the data available, it is not possible to confirm without doubt that these deaths were related to the Bundibugyo virus. However, they show that an unusual health phenomenon had already been observed more than six weeks before the outbreak was officially declared.

Even more so, investigations since May 15 have come to support the thesis that Ebola might have been circulating even earlier than that.

In a study published in the Morbidity and Mortality Weekly Report on June 11, a team of researchers from the US Centers for Disease Control and Prevention (CDC) reconstructed the early course of the epidemic.

An initial transmission from an animal to a human, or spillover, between mid- and late February is “plausible,” the researchers concluded.  A late-April spillover, on the other hand, would be difficult to reconcile with the scale the epidemic had already reached at the time of the study.

WHO: Genome sequencing suggests February outbreak

On August 10, Mohamed Janabi, the WHO Regional Director for Africa, said genome sequencing analyses suggested the outbreak likely began “as early as February 2026.”

Several early infections were mistakenly attributed to diseases that were far more common in the region, particularly malaria and typhus, he said.

In an interview in August, Janabi told DW that there was a significant gap in case reporting. “The Ebola situation is catastrophic… In three months, we only had access to one-third of the patients,” he told DW.

Could ‘pig Ebola’ shed some light on the matter?

Jules Villa, a researcher in the anthropology and ecology of disease emergence at the Pasteur Institute in Paris, points to a phenomenon observed in the connection with previous Ebola epidemics.

His study does not encompass the 2026 outbreak, but takes stock of local reports collected during earlier Ebola outbreaks in northeastern Congo.

Villa shows that livestock farmers, veterinarians and residents had reported unusually high animal mortality even before the outbreak of at least two Ebola epidemics in humans.

In 2017, several witnesses reported on what they called “pig Ebola” — a high mortality among pigs, which was ultimately attributed to swine fever.

According to Villa’s research, monitoring livestock in the general population could provide the first useful warning signs long before an outbreak is confirmed by a laboratory.

This article was originally written in French.