MEXICO CITY (AP) -- The swine flu epidemic crossed new borders Tuesday with the first cases confirmed in the Middle East and the Asia-Pacific region, as world health officials said they suspect American patients may have transmitted the virus to others in the U.S. Most people confirmed with the new swine flu were infected in Mexico, where the number of deaths blamed on the virus has surpassed 150. But confirmation that people have been infecting others in locations outside Mexico would indicate that the disease was spreading beyond travelers returning from Mexico, World Health Organization spokesman Gregory Hartl told reporters on Tuesday in Geneva. The swine flu has already spread to at least six countries besides Mexico. WHO raised the alert level to Phase 4, meaning there is sustained human-to-human transmission causing outbreaks in at least one country. WHO's pandemic alert system was revised after bird flu in Asia began to spread in 2004. Monday was the first time it has ever been raised above Phase 3. (18 images)
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South Korean quarantine officers try to take samples from a baby who arrived from the United States at Incheon International Airport on April 28, in Incheon, South Korea. Getty Images / Song Kyung-Seok
A South Korean quarantine officer monitors a thermal scanner as passengers from an international flight arrive at Incheon International Airport on April 28, in Incheon, South Korea. Getty Images / Song Kyung-Seok
Masked Taiwan government quarantine staffs stand by a check point at the Taoyuan International Airport on April 28. Health authorities in Taiwan said that a man hospitalized with fever after returning from Mexico had not contracted swine flu. AFP / Getty Images / Sam Yeh
A girl, wearing a face mask to protect herself, waits at a bus stop near the international border between United States and Mexico in San Ysidro, California, on April 27, after arriving from Mexico with her family. AFP / Getty Images / Jewel Samad
Students Anna Rooney, left, Ryan Smyth and Damien Chin, right, wear masks after showing flu like symptoms on their arrival from the United States at Auckland International Airport, Auckland, New Zealand, Tuesday, April 28. New Zealand Herald / Greg Bowker
A man reads a newspaper next to a poster urging people to wear masks at Queen Marry Hospital in Hong Kong Tuesday, April 28. AP / Kin Cheung
Quarantine officials with protective masks and outfits make their way to board a commercial plane that has just arrived from Chicago as they check its passengers at Tokyo's Narita International Airport in Chiba, Japan, Tuesday, April 28. The on-board inspection of passengers came after the World Health Organization raised its global alert level Monday, signaling the swine flu virus was spreading from human to human in community outbreaks. AP / Katsumi Kasahara
A couple wearing protective masks talk in a subway station in Mexico City, Monday, April 27. AP / Rodrigo Abd
A man wearing a face mask stands inside a subway train in Mexico City, Monday, April 27. AP / Rodrigo Abd
A barber wears surgical mask as a precaution to ward off contagion from the new multi-strain swine flu virus on April 27, in Mexico City. AFP / Getty Images / Luis Acosta
Dr. Shimoni Tzvi is helped into a protective suit at Laniado hospital in the coastal city of Netanya, Tuesday, April 28. The Israeli Health Ministry on Tuesday confirmed the country's first case of swine flu, saying a 26-year-old man who recently returned from Mexico had contracted the virus. Hospital officials said he has fully recovered. AP / Dan Balilty
Passengers wearing face masks arrive at the Barajas Airport in Madrid on Tuesday, April 28. Spain's health ministry on Tuesday confirmed a second case of swine flu in the country and raised the number of people under observation to 32. AP / Arturo Rodriguez
An airport employee cleans a window while wearing a face mask at the Barajas Airport in Madrid on Tuesday, April 28. AP / Arturo Rodriguez
A group of Mexican high school students wearing face masks listen to the tour operator, right, after arriving at the Barajas Airport in Madrid on Tuesday, April 28. AP / Arturo Rodriguez
Lorenzo Uroza, wearing a protective white mask, is seen in a public bus at the airport in Bilbao, northern Spain, Tuesday, April 28, after returning last week to Madrid from Mexico. AP / Alvaro Barrientos
A Customs and Border Protection officer wears a protective mask while searching the cargo area of a vehicle entering the United States at the San Ysidro Border Crossing in San Diego, Monday, April 27. AP / Lenny Ignelzi
Two nuns waiting at Mexico City's international airport on April 27, wear surgical masks. AFP / Getty Images / Ronaldo Schemidt
A worker of a pizza restaurant wears a surgical mask and prepares himself to close. AFP / Getty Images / Luis Acosta
