UNITED NATIONS | The United States has surpassed Mexico as the world leader in confirmed cases of swine flu.
The United States had 4,714 confirmed cases, according to the official tally by the World Health Organization over the weekend, while Mexico reported 3,103 documented cases.
Of 8,829 people infected in 40 countries, 76 people have died, the WHO said.
“Several weeks after this outbreak began, we are cautiously optimistic that this virus may be less severe than was first feared, said Department of Health and Human Services Secretary Kathleen Sebelius.
She pledged Washington would continue to offer technical or medical assistance to hard-hit countries with vaccine research and antibiotics.
The Atlanta-based Centers for Disease Control and Prevention (CDC) is working with other nations to develop an effective vaccine for the virus.
Officials say it will be at least four months before scientists develop a vaccine.
The H1N1 virus, which causes swine flu, killed an assistant principal at a New York school, bringing to five the number of U.S. deaths from the disease.
New York had 254 “confirmed or probable” cases as of noon Monday, according to the CDC.
The virus has ripped through schools in New York City, with hundreds of students reporting flulike symptoms. Experts say the virus passed easily between siblings, or in crowded rooms.
Sixteen schools in Manhattan in the borough of Queens have been shut down in an effort to control the transmission among the student body.
Chile is the latest country to report a case, bringing the total number of nations confirming infections to 40, the Associated Press reported.
Japan reported the largest jump to more than 130 cases in four days, the AP said. The country closed 1,000 schools in two prefectures to contain the infections, while Tokyo and other cities are filled with frightened Japanese wearing face masks.
Spain and Britain have the highest numbers of cases in Europe, reporting 103 and 101 cases, respectively, the AP reported.
The virus remains a mild strain of flu, according to the Geneva-based WHO, but some scientists warn that could change.
“This virus may have given us a grace period, but we do not know how long this grace period will last,” WHO Director-General Margaret Chan said.
Meanwhile, the AP reported that dozens of countries Monday urged the WHO to change its criteria for declaring a pandemic, saying the agency must consider how deadly a virus is - not just how far it spreads across the globe.
Fearing a swine flu pandemic declaration could spark mass panic and economic devastation, Britain, Japan, China and others asked the global body to consider carefully before raising its alert. Some cited the costly and potentially risky consequences, such as switching from seasonal to pandemic vaccine, even though the virus so far appears to be mild.
Although no formal changes were made Monday, WHO said it would listen to its members’ requests, the AP reported.
The alert for swine flu is now at Phase 5, which means the virus is spreading unchecked inside at least two countries in a single region. Under the existing rules, Phase 6 would indicate outbreaks in at least two different regions of the world and that a pandemic is under way.
Dr. Chan and U.N. Secretary-General Ban Ki-moon are scheduled to meet with senior representatives of pharmaceutical companies Tuesday to discuss the vaccine question. The U.N. declined to name the companies.
The most deadly influenza pandemic of modern times was the “Spanish flu” of 1918-20, with estimates ranging from 50 million to 100 million people killed.
One theory was that the disease was spread by U.S. troops sharing cramped garrisons during the closing days of World War I.
The virulent 1918 strain was so deadly that governments refused to acknowledge it, fearing it would prolong the war by encouraging the enemy to keep fighting.