The United States Centers for Disease Control and Prevention (CDC) warned that the ongoing Ebola outbreak in the Democratic Republic of the Congo could grow into one of the largest in history if public health measures are not rapidly strengthened.

In a series of reports released Friday, the CDC said modelling scenarios show the outbreak of the Bundibugyo strain of Ebola could reach a scale comparable to the 2014–2016 West Africa epidemic, which infected more than 28,000 people and killed over 11,000.

"That scale is possible," said Jason Asher, Director of the CDC's Center for Forecasting and Outbreak Analytics.

The outbreak was officially declared in northeastern DR Congo on May 15, although health officials believe the virus had been spreading undetected before then. According to the latest figures from the World Health Organization (WHO), the country has recorded 452 confirmed cases and 82 deaths, with the epicentre in Ituri Province. Neighboring Uganda has reported 19 confirmed cases and two deaths.

The CDC stressed that its projections are not predictions but planning tools designed to guide the response. However, officials warned that without aggressive intervention, the outbreak could accelerate rapidly.

Under scenarios where only a small proportion of infected patients are identified, isolated and treated, CDC models show a 65% chance that cases could exceed 20,000 within three months.

"The public health response to control this outbreak will likely need to be of similar magnitude to the response for the 2014-2016 West Africa Ebola outbreak," the agency said.

The CDC warning comes as the WHO and the Africa Centres for Disease Control and Prevention (Africa CDC)  jointly appealed for $518 million to support Ebola response efforts across the DR Congo and neighboring countries over the next six months.

Health authorities say the absence of approved vaccines and treatments specifically targeting the Bundibugyo strain has heightened concerns about the outbreak's potential trajectory. While several patients have recovered, experts warn that containing the virus will depend heavily on rapid case detection, isolation, contact tracing and community engagement.

With cases already reported across borders and several countries considered at risk, international health agencies are racing to prevent the outbreak from becoming Africa's most serious Ebola emergency since West Africa's devastating epidemic a decade ago.