Britannicaの2002年版 ***************************以下引用**************************
>> infection:
>> in medicine, the invasion of the body by any of various infectious agents--including bacteria, viruses, fungi, protozoans, and worms--and the reaction of the body to them or to their toxins. When health is not altered, the process is termed a subclinical infection. When health is altered, the process is called an infectious disease.
