A mysterious illness, which the Africa Centers for Disease Control and Prevention is calling "disease X," has killed at least 31 people — mostly children — in the remote Panzi region of the Democratic Republic of Congo, the World Health Organization says.

The WHO said Sunday that 406 cases of the disease have been recorded in the Kwango Province, approximately 435 miles southeast of the capital Kinshasa. More than half of those who died were children younger than 5 years old who were severely malnourished, the health agency said.

The actual number of deaths in the region is difficult to determine, and some reports say as many as 143 people have died. A team of scientists from the World Health Organization is on the ground investigating the illness, which researchers believe started circulating in October.

The DRC's Ministry of Public health sent an alert to WHO on Oct. 29 saying it was concerned about a mysterious illness that had caused "increased" deaths in the Panzi health region, according to the WHO. The ministry said in a press briefing on Dec. 5 that the mortality rate was about 8% and that several deaths were reported outside of health facilities.

The community deaths are of concern, local health officials told CBS News, and the WHO said they need to be investigated.

Doctors say the disease presents much like a respiratory infection, with people suffering from fevers, headaches, coughing, runny noses and body aches. The WHO said rapid response teams have been sent to identify the cause of the outbreak and help coordinate a suitable response.

"The 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 WHO said in a statement Sunday.

"Given the clinical presentation and symptoms reported, and a number of associated deaths, acute pneumonia, influenza, COVID-19, measles and malaria are being considered as potential causal factors with malnutrition as a contributing factor," the WHO said. "Malaria is a common disease in this area, and it may be causing or contributing to the cases."

The area where the outbreak is taking place is remote, located roughly 48 hours by road from the capital Kinshasa. The rainy season, which brings an influx of malaria cases, is complicating the situation, the WHO said. There is also no functional laboratory in the region, and communication infrastructure is limited. The area is also at risk of attacks by armed groups, the WHO said.

Experts have warned about the risks of further spread of the disease and said they have not ruled out that it is airborne. The WHO said the risk at a global level remains low, but that due to the proximity of the boarder with Angola, there is concern of cross-border transmission.

Source