Hypercapnia and Trade Outbreak
Hypercapnia: Excessive carbon dioxide in the blood.
Symptoms and signs of early hypercapnia include flushed skin, full pulse, extrasystoles, muscle twitches, hand flaps, reduced neural activity, and possibly a raised blood pressure. According to other sources, symptoms of mild hypercapnia might include headache, confusion and lethargy. Delirium and Obtundation (dulled alertness)
I think I have spotted a mass outbreak of it. Quick, rush some oxygen masks to Copenhagen...