A Texas woman with the new H1N1 flu died earlier this week, state health officials said, the second death outside of Mexico, where the epidemic appeared to be waning.

Officials said on Tuesday the woman, who was in her 30s, had chronic health problems. U.S. health officials have predicted that the swine flu virus would spread and inevitably kill some people, just as seasonal flu does.

Last week a Mexican toddler visiting Texas also died. Mexican officials have reported 29 confirmed deaths.

The World Health Organization was monitoring the spread of the virus and said 21 countries have officially reported 1,490 cases. The United States has 403 confirmed cases in 38 states, the U.S. Centers for Disease Control and Prevention said, with another 700 "probable" cases. Canada has reported 165 cases.

"Those numbers will go up, we anticipate, and unfortunately there are likely to be more hospitalizations and more deaths," U.S. Health and Human Services Secretary Kathleen Sebelius said.

Health officials said the outbreak seemed to be slowing in Mexico, the country hardest-hit by the virus, which is a mixture of swine viruses and some elements of human and bird flu. At the same time, infections were breaking out globally.

An aircraft carrying 97 Chinese stranded in Mexico by the flu scare was expected to arrive in Shanghai late on Wednesday and all on board appear healthy, state media said.

"Doctors are monitoring the passengers' health," Xinhua news agency quoted China Southern airline as saying, describing them as being "in normal condition".

An AeroMexico plane arrived in Shanghai on Tuesday to repatriate dozens of Mexicans who had become pawns in a drama about how far governments should go to stifle fears that the H1N1 virus could cross their borders.

None of the 43 Mexicans that Beijing quarantined had shown symptoms of the H1N1 flu virus, prompting Mexico to accuse China of being "discriminatory". China denied the allegation, saying isolation was the correction procedure.

Trade skirmishes over pork also worsened, with some countries imposing new restrictions, despite assurances by the United Nations Food and Agriculture Organization that pork, especially cooked pork, was safe to eat.

U.S. and Canadian pig and pork exports have been hit by bans from Russia to Ecuador that rattled the $26 billion-a-year global pork industry, in which Mexico, the United States and Canada are among top exporters.

PANDEMIC ALERT

The question remained how far the virus would spread and how serious would it be. The WHO remained at pandemic alert level 5, meaning a pandemic is imminent.

"If it spreads around the world you will see hundreds of millions of people get infected," the WHO's Dr. Keiji Fukuda told a news briefing.

If it continues to spread outside the Americas, the WHO would likely move to phase 6, a full pandemic alert. This would prompt countries to activate pandemic plans, distribute antiviral drugs and antibiotics and perhaps advise people to take other precautions like limiting large gatherings.

"It's not so much the number of countries, but whether the virus sets up shop in any of those countries like it has here and starts to spread person to person. And given the number of countries that have cases, one would think that eventually that criteria would be met," said acting CDC director Dr. Richard Besser.

He and Fukuda said it would be important to watch the Southern Hemisphere, where winter and the flu season are just beginning.

Other pandemics have started with a mild new virus in spring that has come back to cause severe disease later in the year. WHO said it would begin sending 2.4 million treatment courses of Roche AG's (ROG.VX) and Gilead Sciences Inc's (GILD.O) Tamiflu, an antiviral proven effective against the new flu, to 72 nations.

Fukuda said it was too soon to say whether a new H1N1 vaccine was needed, but scientists have started to make one. U.S. vaccine experts said it would probably be given as two doses, separately from the seasonal flu vaccine.

Mexico began to return to normal, but a five-day lockdown ordered by the government to try to slow the influenza's spread cast a pall on the normally exuberant Cinco de Mayo celebrations.

Mexican Finance Minister Agustin Carstens said the outbreak could knock as much as half a percentage point off growth this year.

"It's having a big impact on our economy," Carstens said. Mexico was already in recession due to a collapse in U.S.-bound exports. Now its tourism industry is being savaged .