May 21 (Bloomberg) -- Two high school students have been confirmed as the first cases of swine flu in the Tokyo area after they returned from a school trip to New York, local government officials said.

The 16-year-old girls, both from the same high school in Kawasaki, a city of 1.3 million people adjacent to Tokyo, returned from a week-long trip to New York on May 19, officials said. Both have been hospitalized with the H1N1 virus, which has sickened more than 10,000 people worldwide.

The cases in the Tokyo area, the world’s largest metropolis with a population of 35.7 million, come as the government this week shut 4,464 schools in western Japan after a swine flu outbreak around Osaka. The Health Ministry today said 283 people have the virus, formally known as A/H1N1.

“At this point it is possible to prevent a large scale spread of the virus in Tokyo because this was not a person-to- person transmission within Japan,” Chief Cabinet Secretary Takeo Kawamura said today at a news conference in Tokyo.

The western Japan outbreak included three workers at branches of McDonald’s Holdings Company (Japan) Ltd. in Hyogo prefecture, spokesman Kenji Kaniya said today by telephone. McDonald’s Japan stock declined 2.7 percent on the Tokyo Stock Exchange, the largest drop since Feb. 4.

Masks Sell Out

Drug stores sold out of medical masks yesterday around Osaka Station, the region’s busiest rail terminal. Sellers had placed 7,647 listings for masks on an auction site run by Yahoo! Japan Corp., operator of Japan’s most visited Internet portal, as of 5.30 p.m. local time.

A total of 13 conferences were canceled at the Osaka International Convention Center.

“We’ve never had this many cancellations,” Hironobu Matsuo, spokesman for the center known as Grand Cube, said by telephone today. “It’s probably worse than the Sept. 11 attacks or the SARS outbreak in 2003,” he said, referring to severe acute respiratory syndrome.

The number of guests has declined at Rihga Royal, a hotel in central Osaka popular with business people, as companies reduce employees’ travel, Kono Hiroaki, a hotel spokesman said today by telephone.

KDDI Corp., Japan’s second-biggest mobile phone operator, canceled a news conference in Osaka to announce its latest mobile phones, citing the swine flu cases.

“I am very concerned about the impact on the economy” from the spread of swine flu, Tadashi Ogawa, head of the Regional Banks Association, said at a press briefing in Tokyo today. The spread of the virus will affect Japan’s manufacturing sector as well as retail and service industries, he said.

WHO Alert

Makers of textiles used in medical masks, including Osaka- based Shikibo Ltd. and Daiwabo Co., gained on the Tokyo Stock Exchange after the new cases. Shikibo rose 4.4 percent and Daiwabo rose as much as 9.9 percent before closing up 0.3 percent, while Japan’s benchmark Topix index fell 0.6 percent.

“Retail, restaurant and leisure businesses will be affected,” said Mitsushige Akino, who oversees about $632 million at Ichiyoshi Investment Management Co. in Tokyo. “As people are likely to stay in their houses, online retailers and mail-order companies will benefit.”

Evidence of human-to-human transmission in a region outside North America, where a majority of the cases worldwide have occurred, may prompt the World Health Organization to raise its pandemic alert by one grade to the highest level, Hitoshi Oshitani, the former head of the agency’s Western Pacific region, said in a May 19 interview.

Japan’s cases include a man in his 20s from Shiga prefecture, near Osaka and Hyogo, who has no record of overseas travel, the health ministry said in a statement. He was in Kobe, in Hyogo Prefecture, on May 16 and 17, it said.

Young Patients

As many as 90 percent of the infections in Japan occurred in teenagers, with nine cases in people in their 20s, five in their 30s, seven in their 40s, three in their 50s, and one aged above 60, the Health Ministry said.

The ministry issued a statement yesterday advising people not to buy Roche Tamiflu Holding AG’s influenza treatment drug over the Internet from overseas, adding that the drug should be used only when prescribed by doctors.

To contact the reporter on this story: Stuart Biggs in Tokyo at sbiggs3@bloomberg.net; Eijiro Ueno in Tokyo at e.ueno@bloomberg.net.

Last Updated: May 21, 2009 05:02 EDT