A parasite of concern in raw or undercooked fish served as sushi or ceviche is:

解析

Anisakis is a roundworm — a parasite — found in raw or undercooked marine fish, which is why fish served raw as sushi or ceviche must be frozen at the required temperature for the required time unless it is exempt; that freezing step is what destroys it. The deciding word in the stem is parasite: Salmonella species are bacteria, Clostridium botulinum spores are bacterial, and Norovirus is a virus — even though Norovirus is also linked to raw shellfish.