This piece calls the disease "respiratory in nature", which does not necessarily mean airborne. Stay tuned, I guess.

Update: Disease X has now infected 416 with 135 deaths.

Apparently it is significantly more challenging to collect and transport samples than they were anticipating, but there is a small update:

All severe cases were reported to be malnourished. There are 145 cases aged 15 and above, of which nine died (CFR: 6.2%). Deaths have primarily occurred in the village communities.

And:

The clinical presentation of patients includes symptoms such as fever (96.5%), cough (87.9%), fatigue (60.9%) and a running nose (57.8%). The main symptoms associated with death include difficulty in breathing, anaemia, and signs of acute malnutrition. Based on the current context of the affected area and the broad presentation of symptoms, a number of suspected diseases need to be ruled out through further investigations and laboratory testing. These include but are not limited to measles, influenza, acute pneumonia (respiratory tract infection), hemolytic uremic syndrome from E. coli, COVID-19, and malaria.

Congo outbreak identified: "The mystery has finally been solved. It's a case of severe malaria in the form of a respiratory illness... and weakened by malnutrition." https://www.reuters.com/world/africa/congos-health-ministry-says-unknown-disease-is-severe-malaria-2024-12-17/

https://bsky.app/profile/carlzimmer.bsky.social/post/3ldj5l54gfc2h

Via Carl Zimmer, the mystery disease has been identified:

The mystery has finally been solved. It's a case of severe malaria in the form of a respiratory illness... and weakened by malnutrition.

There's not a lot of other information yet, but if I had to guess, if it's malaria, that means it is not an airborne disease.