He was admitted to Mahavir Hospital in Surat late last night. A special isolation room had been set up for him, hospital authorities said.
Vasava, the BJP MLA from Mangrol, developed H1N1 virus symptoms in the last few days.
"He had fever for the last three days. To find out the cause, doctors at Gandhinagar Civil Hospital sent his serum samples for test. Yesterday the test confirmed he is infected with H1N1 virus," said Dr M C Dasilva, medical director of Mahavir Hospital.
The Budget Session is to start on Monday. Since Vasava was not expected to preside over it because of his health, somebody from five-member panel of substitute Speakers will take the charge, said Assembly Secretary D M Patel.
The swine flu is rampant across the state this year, with 176 deaths till yesterday.