David Atlas / Retna Ltd. 1 / 2
David Atlas / Retna Ltd. 1 / 2

The Backstreet Boys' Brian Littrell has been diagnosed with swine flu, Usmagazine.com confirms.

The other three band members (Nick Carter, Howie Dorough and AJ McLean) have seen a doctor and are not showing any symptoms. As a preventative measure, the band's doctor has prescribed Tamiflu to the group and their touring party, who had just returned to the United States from Tokyo.

Because of Littrell's illness, the Backstreet Boys canceled their scheduled Monday appearance at the Pinktober Hard Rock Cafe signing in New York City. They will also cancel their performance on CBS' "The Early Show" Tuesday morning. (The rest of their schedule this week has not yet been determined.)

"We were really looking forward to spending time with our closest fans and friends in NYC and take part of Pinktober, an unbelievable and important program," Littrell, 34, said in a statement to Us. "I hope we can come back soon and do everything we can to help."

The news comes one day before the release of their new album, "This Is Us," which goes on sale Tuesday.

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