A 40-year-old-man was admitted to the emergency department for sudden dyspnoea. He had no medical history. He had given up smoking a few years back having had a cigarette consumption of 10 packs/year. He stopped drinking alcohol 2 months ago. He had been a drug (heroin and cocaine) misuser for 15 years. Methadone had been introduced as a substitution therapy since 2012. He came back from a journey to China 1 month beforehand. The day of admission, he awoke with dyspnoea and a dry cough.

In the emergency room, he had no fever, and lung and cardiac auscultation was normal. Oxygen saturation was 94% and the respiratory rate was over 20/min. Laboratory findings showed an increase in the leucocyte count at 18.1 10⁹/L. …