Lalmalsawma said the samples of the suspected H1N1 patient, sent on Tuesday and again on Wednesday to the National Institute of Cholera and Enteric Diseases (NICED), Kolkata were found to be positive.
He said the patient, first treated in a private hospital in Aizawl, was shifted to the ICU of Aizawl Civil Hospital and was being treated there.
Earlier, one Mizo woman who was in Delhi for a brief period, was found infected with swine flu in mid-February, but was completely cured after treatment in Aizawl.
Lalmalsawma said screening of possible H1N1 patients was undertaken at the Lengpui Airport near Aizawl and at the Mizoram-Assam border Vairengte town since February 23.
Screening would also be conducted at other places including border check points along the international border with neighbouring Bangladesh and Myanmar, he added.