INVAZIYA (lot. invasio – daraftodan, hamla kardan), ba organizmi odamu hayvonot vorid shudani parazitho (soddatarinho, gelmintho, bandpoyho). Parazitho dar organizmi homil metavonand zindagi va afzoish karda, yagon osebi jiddi narasonand (nig. Parazithomili) yo boisi rukh namudani bemorihoi gunogun shavand (nig. Bemorihoi paraziti).