a case of (something)
1. A bout of illness. My poor daughter has been sick all week with a case of the measles.
2. By extension, an occurrence of something. Liz usually loves to sing for an audience, so I think she's just got a case of nerves.
*case of something
1. an instance of something. (*Typically: be ~; have ~.) This is a case of police brutality. They should not have injured the suspect.
2. an occurrence of a disease. (*Typically: be ~; look like ~; treat ~.) I am suffering from a case of the flu.