REUTERS - The World Health Organisation said on Saturday that 15 countries have reported 615 infections with the new flu virus A-H1N1, widely known as swine flu.

Most of the increase from Friday's 331 toll reflects the results of ongoing tests from Mexico, which had a backlog of samples in WHO labs, the United Nations agency said.

Mexico, the epicentre of the disease outbreak, now has 397 laboratory-confirmed human cases including 16 deaths, according to the WHO, whose data has been lagging national figures and is considered most authoritative.

The second-most affected country, the United States, has 141 cases confirmed in WHO labs including one death, the Mexican infant whose family crossed the border to seek medical help. Other countries have had the following number of confirmed H1N1 infections, with no deaths: Austria (1), Canada (34), Hong Kong - China (1), Denmark (1), France (1), Germany (4), Israel (2), Netherlands (1), New Zealand (4), South Korea (1), Spain (13), Switzerland (1) and Britain (13).

Mexico has cut its suspected death toll to 101 from as many as 176 because of test samples coming back negative in its labs, the government said late on Friday, in a sign the flu pandemic the WHO says is "imminent" may not be as severe as first feared. On Saturday, the WHO repeated its view that borders should stay open and travel should not be limited as a result of the virus, but said "it is considered prudent for people who are ill to delay international travel and for people developing symptoms following international travel to seek medical attention.

"Individuals are advised to wash hands thoroughly with soap and water on a regular basis and should seek medical attention if they develop any symptoms of influenza-like illness," the WHO said on its website.

Sanborns department storeDR The only people at the Sanborns supermarket are the staff. They all wear masks. The Sanborns department store pharmacyDR "We're not taking any risks," says one employee. Out on the street, the few people out and about seem subdued. Less than half are wearing face masks. Most of those who do have them hanging from around their necks, instead of over their mouths and noses. Juana came to Mexico City to find workDR Juana left Oaxaca 11 years ago to come and work in Mexico City where she is a street cleaner. She is frustrated and feels overwhelmed by events. "It's worrying, but I don't really uderstand what's going on"DR Like many in Mexico, Juana is worried for her family and friends. Manuel and Concepcion don't see the point of wearing masksDR The couple are convinced the masks will not help protect them from the virus. "I still keep one in my pocket," Concepcion says. Ulises and EdithDR Edith is a student, but the university has been closed until at least May 6. She stays at home and spends her evenings with Ulises, who would rather do the same but is worried about losing his job. "Life hasn't changed," Edith insistsDR Edith and Ulises are aware that the crisis is growing, but they are staying calm above all. At work, Ulises wears a face mask. He also uses public transport and does the shopping. But when they are together the masks come off. Photos: Gallagher Fenwick