Its symptoms include optimism, politeness, affection, happiness, lack of "grouchiness", and just generalized "niceness". Oscar and his niece Irvine and both got it in Episode 2630. Later, in Episode 3589, Telly Monster worried that Oscar had caught it again when he was reading "nice books", but he didn't have it. In Sesame Street Home Video Visits the Hospital, a young Grouch girl is in hospital with a disease, possibly Grouch Flu, whose symptoms include "feeling cheerful". When Big Bird recovers and leaves, so does the Grouch girl, who claims she is "feeling much worse".