The deadliest and fastest-growing Ebola outbreak on record has claimed more than 1,000 lives in the Democratic Republic of Congo, where health authorities are struggling to contain a strain of the virus that has no approved vaccine or treatment.
The latest update from Congo's public health institute reported 2,536 confirmed infections and 1,033 deaths since the outbreak was declared on May 15. At least 738 patients remain hospitalized or in isolation as health workers race to curb transmission across the country's east.
Unlike previous Ebola emergencies, the current epidemic is driven by the Bundibugyo strain, a rare variant for which no licensed vaccine or proven treatment exists. The absence of medical countermeasures has made the outbreak especially difficult to control.
Most infections are concentrated in the remote eastern province of Ituri, which accounts for nearly 90% of confirmed cases. However, the virus has spread to five provinces, including the major city of Kisangani, and crossed into neighboring Uganda.
Outbreak remains dangerous
Congolese health officials say the explosive increase in infections appears to be easing, but they warn the outbreak has not yet reached its peak.
The country's latest epidemiological report says transmission remains widespread, with recent fluctuations in case numbers partly reflecting reporting delays and ongoing data verification.
One of the biggest concerns remains contact tracing. Officials say only about 77% of known contacts are currently being monitored, far below the 95% threshold considered necessary to interrupt transmission.
Health responders also continue to grapple with major gaps in understanding how widely the virus has spread, as many infections cannot be linked to known transmission chains.
One of the worst ever
Researchers at the U.S. Centers for Disease Control and Prevention recently used computer modeling to examine the epidemic's trajectory.
Their analysis suggested that, under a worst-case scenario, the outbreak could approach the scale of the devastating West African Ebola epidemic between 2014 and 2016, which killed more than 11,000 people.
That earlier outbreak took roughly eight months to surpass 1,000 deaths. Congo's current epidemic has reached that milestone significantly faster.
Adding to the uncertainty is the unknown origin of the outbreak. The World Health Organization says most new infections are emerging from unidentified chains of transmission, making it increasingly difficult to track and isolate cases.
Regional threat
The WHO continues to classify the outbreak as posing a "very high" risk within Congo and a "high" risk for Uganda and neighboring countries because of ongoing cross-border movement and sustained community transmission.
The agency maintains that the global risk remains low because Ebola spreads only through direct contact with the bodily fluids of an infected person, unlike airborne respiratory viruses.
WHO officials acknowledge that additional imported cases are likely as the epidemic expands but note that those detected outside Congo have so far been quickly isolated, preventing sustained transmission.
The CDC echoed that assessment, emphasizing that Ebola is not spread through the air.
"You cannot get Ebola from being near someone," the agency said.
The CDC also noted that infected individuals become contagious only after developing symptoms, making it easier to identify cases and trace contacts than diseases capable of spreading before symptoms appear.
International precautions
Uganda has confirmed 20 Ebola infections, including two deaths, all linked to travelers arriving from Congo. The cases have been concentrated in the capital, Kampala.
No new infections have been reported there since June 21. The WHO has discharged its final patient, beginning the standard 42-day observation period required before declaring the outbreak over.
Outside Africa, France reported a single imported case involving a doctor who had traveled from Congo. He has since recovered fully and been released from the hospital.
The United States has maintained strict travel measures, barring most recent travelers from Congo while requiring American citizens returning from the country to spend 21 days outside Congo before re-entering the U.S. Travelers arriving from Uganda and South Sudan are directed through designated airports for Ebola health screening.
Meanwhile, plans to establish an Ebola quarantine facility in Kenya for evacuated Americans have faced legal challenges and public protests, some of which have turned violent.
Conflict and mistrust
Health officials say medical challenges are being compounded by widespread distrust among local communities.
Rumors surrounding Ebola treatment centers, fears of forced isolation and resistance to safe burial practices have discouraged many people from seeking testing or medical care until they become critically ill.
Violence has further undermined containment efforts. Ongoing fighting involving Rwanda-backed M23 rebels, attacks by the Islamic State-linked Allied Democratic Forces and the displacement of thousands of civilians have disrupted surveillance operations, delayed contact tracing and limited access to affected communities.
Local authorities said suspected ADF militants killed at least 16 people in an attack on a village in Ituri province on Wednesday, underscoring the insecurity facing health workers.
Experimental treatments
With no approved vaccine or treatment available for the Bundibugyo strain, researchers have begun testing potential therapies in the middle of the outbreak.
Earlier this month, scientists launched the first clinical trial targeting the virus, enrolling patients at an Ebola treatment center in Ituri.
The WHO said as many as 1,000 participants may be needed before researchers can determine whether either of the two experimental treatments is effective, a process expected to take several months.
"There’s never been an Ebola outbreak that started with so many cases because it was so late to be identified," said Trish Newport, emergency program manager for Médecins Sans Frontieres, also known as Doctors Without Borders, who has been working in Congo.