Unknown Illness Kills Dozens in Congo as Experts Clash on Cause

The mystery behind an unknown illness that has killed dozens in the Democratic Republic of Congo just 48 hours after they first showed symptoms deepened after the World Health Organization on Friday offered a new theory that seemingly contradicts African medical experts.

At least 60 people have died and more than 1,000 have been sickened in Congo’s Équateur Province by the illness, which is characterized by “fever, headache, chills, sweating, stiff neck, muscle aches, multiple joint pain and body aches, a runny or bleeding nose, cough, vomiting and diarrhea,” according to the latest W.H.O. report issued on Thursday.

At a news conference in London on Friday, Dr. Michael Ryan, director of emergencies for the W.HO., said the illnesses were most likely caused by poisoning, contradicting a theory proposed on Thursday by experts at the African Centres for Disease Control and Prevention who speculated malaria was to blame.

“Based on onset of symptomatology to death,” Dr. Ryan said, “it looks and appears very much more like a toxic type event, either from a biologic perspective like a meningitis or from a chemical exposure.” He added that there was “a very strong level of suspicion,” that the poisoning was related to “a water source.”

Investigators determined the initial outbreak began in the northwestern village of Boloko before spreading to nearby Danda village, the W.H.O. said. A second, larger outbreak occurred in Bomate village.

Preliminary investigations traced the outbreak to three children who in January ate a bat and died. Before death, the children had all bled from their noses and vomited blood.

Viruses in bats are known to cause a number of diseases in humans and are thought to be natural reservoirs for Marburg and Ebola viruses, two hemorrhagic fevers that are the source of continuing outbreaks in the region.

Laboratory testing yielded negative results for both Marburg and Ebola, the W.H.O. said, but around half of the samples tested positive for malaria, which is rampant in the region. Samples are also being tested for meningitis.

On Thursday, Dr. Ngashi Ngongo from the Africa Centres for Disease Control and Prevention said in a virtual news conference that early testing indicated a connection to malaria.

The Équateur sickness “is very much similar to what happened in Panzi last year,” Dr. Ngongo said, referring to a flulike illness that infected hundreds of people in the southwestern part of the country. The illness was later found to likely be a respiratory infection complicated by malaria.

Though the W.H.O. said it had been assisting local authorities, aid to the country has likely been diminished by recent U.S. funding cuts.

Before recent cuts to U.S.A.I.D. by the Trump administration, the United States may have deployed experts to Congo’s hot zone. Today, there are fewer than 10 people employed at what remains of the agency, to respond to outbreaks around the globe, including those caused by Ebola, mpox and Marburg.

The outbreak in northwestern Équateur Province is several hundred miles away from an ongoing war and deepening humanitarian crisis in eastern Congo where the Congolese military is battling Rwanda-backed rebels.

Stephanie Nolen contributed reporting.