UNITED NATIONS | The World Health Organization on Monday urged nations not to take extreme measures to combat the spread of a new flu strain, even as Mexico announced the end of its five-day shutdown of public gathering places and nonessential government services.
Senior U.N. officials repeatedly urged lawmakers not to impose unwarranted quarantines, not to ban the import of pork and other goods, and not to impose travel restrictions on the nationals of hard-hit countries.
The officials did not name countries, but the appeal was issued as China and Mexico engaged in a diplomatic spat that had planes from the two countries crisscrossing in the skies to bring home stranded or quarantined nationals.
"Let me make a strong plea to countries to refrain from introducing measures that are economically or socially disruptive and have ... no clear public health benefits," Margaret Chan, director-general of the World Health Organization, said in a video link with the U.N. General Assembly.
"Rational responses are always best," she said. "More so in a time of economic downturn."
Her remarks were likely aimed at Beijing, which has quarantined scores of Mexicans, Canadians and others presumed to be infected with the A-H1N1 virus, known as swine flu. China, rocked by severe acute respiratory syndrome (SARS) and then the avian flu epidemic, responded to warnings quickly, but perhaps too bluntly, some Western health officials said.
The new virus has spread across the U.S. The federal Centers for Disease Control and Prevention and state health authorities have confirmed about 300 cases in 36 states. Dr. Richard Besser, acting director of the CDC, said Monday there were about 700 more probable cases in 44 states.
Authorities have confirmed four out of 15 suspected cases in Maryland, plus four in the District of Columbia.
Twenty University of Delaware students have contracted mild versions of virus as well, a figure that is likely to climb when the remaining cases are tested.
But emphasizing that some things are back to normal, St. Francis Preparatory School in New York, which had the biggest known U.S. cluster of cases, reopened Monday with visits by Mayor Michael R. Bloomberg and scores of reporters.
Mexican officials also announced that restaurants, offices and libraries would reopen Wednesday, while schools and entertainment-related assemblies will open later in the week.
"This is about going back to normalcy but with everyone taking better care," President Felipe Calderon said.
As of Monday, Mexico had 727 confirmed cases and 27 deaths, though those numbers are far below what it had reported as probable cases and deaths in the early days of the outbreak - numbers that peaked at nearly 3,000 suspected cases and 168 deaths.
Mr. Calderon also maintained his nation's diplomatic offensive Monday, saying other governments are discriminating against his citizens, effectively punishing Mexico for its honesty in reporting an outbreak to other countries.
Besides China, three of Mexico's Latin American neighbors - Argentina, Cuba and Peru - have banned regular flights or travel to and from Mexico. Two dozen countries have imposed embargoes on pork products from Mexico, the United States and Canada.
"If they weaken us economically or in other ways, Mexico will be able to focus much less attention and funds on this problem," Mr. Calderon said.
Beijing denied it was discriminating against Mexicans, and, in a goodwill gesture, finished sending Mexico $5 million in flu-prevention equipment, ranging from masks and disinfectants to infrared thermal scanners.
As of Monday afternoon, the WHO has confirmed 1,085 cases of swine flu in 21 countries, Dr. Chan told the U.N. General Assembly via videolink from Geneva. The WHO number is significantly lower than most other estimates, as it counts only cases analyzed in its own laboratories.
The virus has killed only Mexicans. One death has been reported in the United States - that of a toddler who was brought to the country from Mexico. The first severe case in Canada was reported Monday.
The organizations say their mounting numbers are mostly the result of confirmations, not new cases.
The A-H1N1 strain - thought to be a stew of swine, avian and human viruses - has not been as lethal as WHO doctors feared. Only 38 percent of the suspected cases in Mexico have turned out to be swine flu, and no deaths from the disease have been reported in Mexico since April 29.
But Health Minister Jose Angel Cordova acknowledged to reporters in Mexico City that about 100 early deaths in which swine flu was suspected may never be confirmed because mucous or tissue samples were not collected.
Dr. Besser was also optimistic Monday, saying that "there are encouraging signs" of a leveling off of the swine-flu threat, though he declined to go as far as his Mexican counterparts in declaring the epidemic under control.
"I'm not ready to say that yet," Dr. Besser said when asked about indications by Mexican health authorities that the disease has peaked there. "We are by no means out of the woods."
Pandemic infections have come in waves, "and you don't know what this virus is going to do."
Meanwhile on Monday, U.S. health officials said they were reconsidering a recommendation, made last weekend, that schools with suspected cases consider closing for up to two weeks.
"We are looking at our school closure guidance," Dr. Besser said. "We're having very active discussions about whether it's time to revise that."
Dr. Besser said it may make more sense to "really push hard on the personal responsibility," encouraging teachers to look out for sick children and insist that parents keep them home.
According to the Department of Education, more than 530 schools in 24 states had given 330,000 students unexpected time off as of Monday.
At St. Francis Preparatory School, as many as 1,000 people connected with the school had flulike symptoms after some students returned from a spring-break trip to Cancun, though only 45 cases were officially confirmed and health officials didn't bother with testing because the symptoms were mild.
"It's a little nerve-racking, being back in school, knowing that there was a swine flu outbreak in school," said junior Paulina Janowiec, 17. "But it's good to be back."
In her remarks to the United Nations, Dr. Chan did not mention Mexico, but the emphasis on excessive measures by others may be a peace offering to the southern neighbor of the United States.
Mexico's chief epidemiologist, Dr. Miguel Angel Lezana, recently told the Associated Press that he had reported a suspicious rash of flu infections, but the Pan American Health Organization, a regional division of the WHO, was slow to pass the information up the organizational ladder.
Dr. Lezana said the division did not share his concern with WHO authorities for two full days, instead of reporting the news immediately.
"It seems it should have been more immediate," Dr. Lezana, director of Mexico's National Epidemiology Center, told AP in a telephone interview.
WHO did not respond to the complaint Monday.
Dr. Chan told diplomats that a pandemic will be declared "when we see [outbreaks] in another region outside North America, showing [person-to-person] transmission." WHO officials stressed that the scale refers to geography, not severity.
"We don't know how long we have until we move to Phase 6," the top of the assessment scale, Dr. Chan said. "We are not there yet."
Phase 6 means a global pandemic - that the virus is transmitted person-to-person on at least two continents. The scale was created in 2005, after the spread of SARS and then the deadly bird flu epidemic, H5N1, which killed at least 220 people and decimated Asian poultry farms.