These are all words for a medical problem. 以上各词均表示健康问题。

• disease a medical problem affecting humans, animals or plants, often caused by infection 常指人、动植物感染的病、疾病：◆He suffers from a rare blood disease. 他患有一种罕见的血液病。
• illness a medical problem, or a period of suffering from one 指病、疾病或患病期：◆She died after a long illness. 她久病不愈而亡。

disease or illness? 用 disease 还是 illness？

Disease is used to talk about more severe physical medical problems, especially those that affect the organs. Illness is used to talk about both more severe and more minor medical problems, and those that affect mental health. * disease 指较严重的身体疾病，尤其是影响身体器官的疾病。illness 指重病或小病均可，也可指精神上的疾病：◆heart/kidney/liver illness◆mental disease Disease is not used about a period of illness. * disease 不指患病期：◆She died after a long disease.

• disorder (rather formal) an illness that causes a part of the body to stop functioning correctly 指失调、紊乱、不适、疾病：◆a rare disorder of the liver 一种罕见的肝病 NOTE A disorder is generally not infectious. Disorder is used most frequently with words relating to mental problems, for example psychiatric, personality, mental and eating. When it is used to talk about physical problems, it is most often used with blood, bowel and kidney, and these are commonly serious, severe or rare. * disorder 一般不传染，多与有关精神问题的词连用，如 psychiatric/personality/mental/eating disorder（精神错乱；人格障碍；精神紊乱；进食障碍）。谈到身体方面的问题常与下列词连用，如 blood/bowel/kidney disorder（血液病；肠道失调；肾脏疾病），这些疾病一般用 serious、severe 或 rare 等词修饰。
• infection an illness that is caused by bacteria or a virus and that affects one part of the body 指由细菌或病毒引起的身体某部位的感染或传染疾病：◆a throat infection 喉部感染
• condition a medical problem that you have for a long time because it is not possible to cure it 指因不可治愈而长期患有的疾病：◆a heart condition 心脏病
• ailment (rather formal) an illness that is not very serious 指轻病、小恙：◆childhood ailments 儿童期小病
• bug (informal) an infectious illness that is usually fairly mild 指轻微的传染病、小病：◆a nasty flu bug 严重的流感

Patterns

• to have/suffer from a(n) disease/illness/disorder/infection/condition/ailment/bug
• to catch/contract/get/pick up a(n) disease/illness/infection/bug