The World Health Organization says more than 400 cases of a mysterious, deadly, flu-like illness dubbed as “Disease X” have been recorded in the Democratic Republic of Congo. The health body, which has dispatched a team to unravel the mystery, is struggling to uncover its origins.

Local authorities say the unidentified disease has infected an estimated 406 people in the DRC since October and killed 143 of them—mostly children. Officials say the outbreak's center is in a remote area of the Kwango province, where poor road conditions and heavy rain mean it takes at least two days to get there.

According to the DRC’s Ministry of Public Health, the mortality rate for the illness has been around 8 per cent, and several deaths were reported outside of health facilities.

According to the WHO, apart from the remoteness of the epicenter, the investigation is being hampered by the fact that all of the most serious cases of “Disease X” involve the patient suffering from severe malnutrition, also making it harder to trace the illness’s exact source. “These challenges, coupled with limited diagnostics in the region, have delayed the identification of the underlying cause,” the WHO said in a statement.

“Teams are collecting samples for laboratory testing, providing a more detailed clinical characterization of the detected cases, investigating the transmission dynamics, and actively searching for additional cases, both within health facilities and at the community level,” the organization said.

According to the initial findings, reports suggest the deaths may have been related to many other diseases spreading in the southwest DRC—including acute pneumonia, influenza, COVID-19, measles, and malaria—as all are common in the region.

WHO says more than one disease may be causing the deaths.

According to the DRC’s Ministry of Health, all recorded cases of the illness involve patients suffering:

• Fever
• Headache
• Cough
• Runny nose
• Body aches
• Breathing difficulties
• Anemia

While the WHO said it has only found evidence of 31 deaths caused by “Disease X,” most of which involve children under five years old, it acknowledged that the death toll may be higher.

Even though the Africa Centers for Disease Control and Prevention have warned that Disease X may be airborne, questions remain on the exact nature of the disease and how it is transmitted. According to the WHO, the risk at a global level remains low as of now, but due to the proximity of the border with Angola, there is concern about cross-border transmission as well.

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