Health officials in the Democratic Republic of Congo are facing significant challenges in controlling an Ebola outbreak that has grown into one of the largest on record, partly due to delays in accurate testing. The outbreak, caused by the rare Bundibugyo species of the virus, was not officially declared until mid-May, nearly a month after initial samples were collected.
The delay occurred because the primary testing machines used in the region, GeneXpert devices, could not detect this particular strain. As a result, suspected cases ballooned to over 1,100, overwhelming laboratories and hampering early response efforts.
According to Jean-Jaques Muyembe, general director of the DRC's national biomedical research center, the first samples were tested on April 30 using GeneXpert machines, which automate the detection of viral DNA. All results came back negative.
It was only after samples were sent hundreds of miles to Kinshasa for more specialized testing that the Bundibugyo strain was identified. This month-long gap allowed the virus to spread unchecked, particularly in the northeastern region near the mining town of Mongbwalu.
Since then, diagnostic capacity has improved. The introduction of RADI-One machines, which can detect Bundibugyo and require less training and equipment, has enabled testing in smaller clinics closer to the outbreak.
Currently, seven labs and one mobile lab are processing tests across northeastern DRC, with the lab in Bunia handling over 100 samples per day. The backlog of cases has mostly disappeared, and turnaround times range from one to twelve hours.
However, officials warn that current capacity is insufficient to keep pace with projections from the U.S. Centers for Disease Control and Prevention, which estimate the outbreak could reach 20,000 cases by August.
Abdirahman Mahamud, who directs health emergency operations at the World Health Organization, acknowledged that while testing has improved, "we are very much aware we are still behind the curve." He noted that additional surge capacity will be needed if transmission continues or case loads increase. The Africa CDC is working to deploy 50 RADI-One machines by the end of June, but experts say more will be needed, and the manufacturer, KH Medical, is a small South Korean company with limited production capacity.
Sample transport remains a major bottleneck, with some areas nearly inaccessible due to ongoing conflict, population displacement, and community mistrust. Rapid tests, similar to those used during the COVID-19 pandemic, could provide results in minutes and help screen both the living and the deceased.
However, no rapid tests are currently approved for the Bundibugyo strain. Developing a new test could take months, but validating existing tests designed for more common Ebola species might be done more quickly.
Ranu Dhillon, a global health physician who advised Guinea during the 2014 Ebola outbreak, said that evaluating these tests on patient samples could be done relatively quickly.
Caia Dominicus, senior technical adviser for the International Pandemic Preparedness Secretariat, emphasized that diagnostics are often overlooked compared to vaccines or therapeutics. "It's underfunded, but they give us the information we need to make key decisions," she said.
"Without them we're flying blind." The delay in diagnostic ability, she added, set the response back significantly, and if appropriate diagnostics had been in place earlier, the outbreak might not have grown so large.