LOS ANGELES AND MEXICO CITY — Encouraged by the mildness of H1N1 flu infections so far, U.S. health officials said Tuesday that they would no longer encourage the closure of schools with confirmed cases of the disease.
Instead, they urged parents whose children exhibited symptoms of influenza to keep them home for at least a week.
In Texas, officials announced the first death of a U.S. citizen from the outbreak. They said a 33-year-old schoolteacher from Harlingen, on the border with Mexico, died early Tuesday. The Texas Department of State Health Services said on its website that the woman had "underlying health conditions" and had recently given birth, but gave no further details.
The only previous U.S. death was a nearly 2-year-old Mexican boy who died last week at a Houston hospital.
The deaths come as little surprise: Health experts have been saying since the start of the outbreak that they expected it to be deadly as more people became infected.
The decision about schools does not represent a major policy shift but rather a recognition that the virus is not proving to be especially threatening, officials said.
"This is a more mild version of the disease than originally feared," said Kathleen Sebelius, secretary of the Department of Health and Human Services. "The lethality seems to be lower."
It was only a week ago that the Centers for Disease Control and Prevention recommended that schools with at least one confirmed case of H1N1 close for as long as 14 days. About 750 schools around the country have done so.
Dr. Richard Besser, acting director of the CDC, said the widespread closings had been a hardship for parents, many of whom did not have adequate sick leave from work to care for their children.
"The downsides of school closure begin to outweigh the benefits," he said.
As lab technicians worldwide continued to plow through the backlog of samples to be tested, the number of new confirmed cases continued to rise, reaching 511 in the U.S. as of Tuesday afternoon and more than 1,700 worldwide.
In Mexico, authorities said the flu outbreak had deeply damaged the economy. It has cost the nation an estimated $2.4 billion, Finance Minister Agustin Carstens said.
But he expressed optimism for a rapid recovery because no fundamental infrastructure had been destroyed and stimulus spending could easily revive languishing businesses.
The government said a planned $2-billion stimulus package would include temporary tax breaks, discounted social security payments and a $40-million promotional fund for tourism and airline businesses, hit hard by canceled flights and a precipitous drop in visitors to Mexico.
Carstens said the country's goal would be to "rebuild confidence."
Health Secretary Jose Angel Cordova said the total number of confirmed H1N1 cases in Mexico had reached 866. Of 140 deaths thought to be linked to the flu strain, 29 have been confirmed by Mexican health authorities and 37 cases await testing, Cordova said.
The CDC has confirmed H1N1 in an additional 86 deaths in Mexico, bringing its death total in the country to 115.
Some deaths will never be confirmed one way or another, Cordova said. He did not give an explanation, but other Mexican health officials said it was because bodies had been buried without samples being taken.
Mexico is slowly starting to emerge from its disease-induced shutdown after President Felipe Calderon said schools would begin to reopen by the end of the week. Restaurants can reopen today, with other public gathering places such as museums and churches allowed to resume activities Thursday.
On Tuesday, proprietors were cleaning restaurants and cafes, and teams of government workers were disinfecting schoolrooms, bus railings and subway ticket dispensers throughout Mexico.
Calderon presided over a subdued Cinco de Mayo celebration in Puebla. The holiday, which in Mexico is mainly observed in Puebla, commemorates the defeat of Napoleon's invading troops by the Mexican army on May 5, 1862.
Speaking in epic terms, Calderon compared that victory to Mexico's fight against the flu.
"Today, almost a century and a half later . . . Mexico faces a new threat; this time, a very different, uncommon threat -- the appearance and spread of an epidemic that put the lives and health of Mexican families at risk. Undoubtedly, this has represented a challenge of unknown magnitude," Calderon said, adding that he thought the government had responded quickly and effectively.
Speaking at the World Health Organization's daily news conference in Geneva, Assistant Director-General Dr. Keiji Fukuda said public health monitors had been looking without success for signs of sustained human-to-human transmission of the virus in Europe or elsewhere.
"We do not feel that we are seeing that right now," he said.
Such transmission outside North America would be the primary criterion for raising the infectious disease alert level to Phase 6, the highest level, so such a change does not appear imminent.
Also Tuesday, the U.S. Navy said it was canceling a planned humanitarian mission to the South Pacific by the San Diego-based ship Dubuque after a crew member was confirmed to have H1N1 and 49 others developed symptoms. The other 370 crew members were placed on a 10-day regimen of the antiviral drug Tamiflu.