Congo’s health ministry told Reuters this week that malaria was the culprit: “The mystery has finally been solved. It’s a case of severe malaria in the form of a respiratory illness,” it said Tuesday in a statement, according to Reuters. The ministry did not respond to multiple inquiries from NBC News.

A mystery illness found in a remote part of Congo has been officially identified as a severe form of malaria, which has sickened nearly 600 people and killed 143.

Malaria has been identified as the likeliest cause of an illness that has killed more than 80 people in south-western Democratic Republic of Congo, Africa's main health agency said. Victims of the previously unknown disease had been suffering flu-like symptoms such as fever,