On May 25, as World Health Organization (WHO) member states wrapped up the World Health Assembly, WHO Director General Tedros Adhanom Ghebreyesus warned that the latest Ebola epidemic is outpacing current response efforts and emergency teams are "playing catch-up."

His warning came 10 days after the Africa Centers for Disease Control and Prevention (Africa CDC) declared the outbreak in the Democratic Republic of Congo (DRC), citing 246 suspected cases and 65 deaths. During this short period, the confirmed and suspected case count has doubled, making this event already the third-largest Ebola outbreak on record.

Speculation has arisen as to how long the Bundibugyo virus—the Ebola species causing the incident—had already been spreading. Many critics blame the dissolution of the U.S. Agency for International Development (USAID), staffing cuts at the U.S. Centers for Disease Control and Prevention (CDC), and the disruption of U.S. foreign assistance funding for limiting country-level surveillance capacity. Others fault WHO for being too slow to share the notification and the isolated rural conditions of the affected areas.

Below, we examine what is known publicly about the timeline of the current Ebola emergency and compare how responses were handled during five other outbreaks that occurred between 2000 and 2021. These examples capture the two largest Ebola outbreaks in history and the responses that took place during four previous U.S. presidential administrations, as representative examples of prior outbreaks.

The data suggest delayed detection—defined here as the time between the index case and confirmation of the Ebola outbreak by health officials—for the ongoing crisis. Yet the early response has been prompt so far. The coming weeks and months will determine whether the gaps that slowed detection will also hamper an effective long-term response.

An Ebola outbreak circulating undetected for weeks or months is a collective failure of global health security, regardless of cause. If the U.S. government, WHO, and Africa CDC were all operating at full capacity while this happened, that's arguably more alarming than the alternative. More likely, these and other international actors were hampered by persistent gaps in global capacity and insufficient resources dedicated to disease surveillance—and the outbreak spread as a result. Understanding why the outbreak is already so large is essential for our collective health security—now and for the future.

Timeline of the 2026 Outbreak

Much remains unknown about the evolution of this outbreak, including the precise timing and location of the index case, the first patient. WHO has stated that the first known suspected case is a nurse who presented with symptoms on April 24 in Bunia, although it is possible, if not likely, that the health worker was infected while treating an ill patient.

Two weeks ago, CDC estimated that an index case had occurred around April 1, and separately the Red Cross said three of its now-deceased workers had likely been exposed in late March. Those comments and unexplained reports of Ebola-like illness in March have raised questions about whether the index case was much earlier.

WHO officials said that they were first notified of a suspected outbreak on May 5 and waited for the completion of confirmatory testing to make a public announcement on May 15.

As of June 1, the Ministry of Health in DRC has confirmed 321 cases and 48 deaths, and another 116 suspected cases are under investigation. The Ministry of Health in Uganda has confirmed nine cases and one death. Brazil has cleared two suspected cases after they tested negative, while the same occurred for possible incidents in India and Italy. At least one American has tested positive for Ebola and been evacuated from DRC to Germany for treatment.

Delayed Detection of the Outbreak

If an outbreak's early phase can be judged by the number of cases and deaths at the time of public announcement, the ongoing emergency would rank first in history.

Its size at the time of international confirmation—246 suspected cases and 65 suspected deaths—is five times larger than the West Africa Ebola outbreak that was announced in March 2014 and led to more than 28,600 cases and 11,325 deaths by the time it was declared over.

As with past Ebola outbreaks, the U.S. government publicly acknowledged and committed to respond to the latest incident quickly after it was announced. The U.S. government also released a health alert soon after detection of the 2026 outbreak, similar to its actions with most previous outbreaks.

The longest delays from detection to a public health emergency of international concern (PHEIC) declaration occurred during the 2018–20 outbreak, the second largest in history. The 2014–16 emergency ranks second in delay length. Across the board, the fastest detection and response from the U.S. government occurred in 2021, at the height of the COVID-19 pandemic, when health teams were overstretched but on high alert for unexplained illness.

It took about six months for the West Africa crisis to reach a size similar to the current emergency in the DRC. In other words, if the ongoing outbreak began at a pace similar to the West Africa outbreak, then it likely started many months ago.