What does the suffix '-iasis' signify in medical terminology?

The suffix '-iasis' is commonly used in medical terminology to denote a condition that is typically associated with a disease or abnormal state, often implying the presence of a pathological process or an infestation. This suffix is frequently used to describe the presence of a particular disease or the abnormal condition caused by parasites, such as in the terms "psoriasis" (a skin condition) or "schistosomiasis" (infection caused by worm parasites).

In contrast to the other options, which refer to different concepts in medical terminology—such as processes, surgical procedures, or treatments—the suffix '-iasis' specifically highlights the nature of the state or condition affecting an individual, making it an essential part of many medical terms that describe diseases.