NAHA, Okinawa Pref. (Kyodo) A 57-year-old man from Okinawa Prefecture has become the first person in the nation to die of H1N1 swine flu, the Okinawa Prefectural Government said Saturday.

More than 4,000 people have caught the new flu, known locally as "shingata" (new-type) influenza, since Japan's first case was confirmed in May.

The patient, a resident of Ginowan, was suffering from a heart and kidney illness, the prefectural government said.

The man fell ill on Aug. 9, complaining of a sore throat, and developed a 37-degree fever the following day. A simple examination indicated he did not have H1N1.

But after his temperature hit 39 on Wednesday, local health authorities conducted another simple examination, in which he tested positive for the type A influenza, the local government said.

Despite treatment with Tamiflu, the man's condition deteriorated until he died at 6:54 a.m. Saturday, authorities said, adding an additional, more detailed, test confirmed that he had indeed caught swine flu.

No one who was in close proximity to the man has developed swine flu symptoms, Okinawa Prefecture officials added.