Disease or illness; a somewhat formal/medical term for sickness often used in official or clinical contexts.
その地域では新たな感染性疾病が確認されたと保健所が発表した。
The health department announced that a new infectious disease was confirmed in the area.
疫病や疾病の予防には衛生対策が重要だ。
Hygiene measures are important for preventing epidemics and diseases.
長期の疾病により働き方を見直す必要が出てきた。
Because of a chronic illness, it became necessary to reconsider the way of working.