There are many causes of inflammation. It can happen due to infiltration of microorganisms and helminths (parasites); to trauma; to some mechanical, thermal, and chemical agents; to some immune reactions; to hypersensitivity/ allergy; and to malignant neoplasms. Each of these causes, although exhibiting symptoms that are very similar, have very different mechanisms to starting inflammation. The outcome of inflammation can also vary considerably, with the best outcome being resolved, [[Acute Inflammation|acute inflammation]], with the worst being continuing, [[Chronic Inflammation|chronic inflammation]].