(AP) -- Three more New Zealanders recently returned from Mexico are suspected of having swine flu and Spain announced the first confirmed case of the deadly virus in Europe on Monday, as countries rushed to screen travelers for fevers.
World Health Organization spokesman Peter Cordingley said the new virus was spreading quickly in Mexico and the southern United States, raising fears of a global pandemic.
"These are early days. It's quite clear that there is a potential for this virus to become a pandemic and threaten globally," Cordingley, WHO's spokesman for the Western Pacific, told AP Television News.
"But we honestly don't know," he added. "We don't know enough yet about how this virus operates. More work needs to be done."
As of late Sunday, the number of suspected swine flu cases in Mexico had climbed to 1,614, including as many as 103 deaths, according to Health Secretary Jose Angel Cordova. The United States has confirmed at least 11 cases of swine flu, and Canada six cases.
Spain's Health Minister Trinidad Jimenez said the confirmed case was found in a young man who recently returned from Mexico. The man is responding well treatment. Another 20 people in the country are suspected of having the disease.
Meanwhile, New Zealand was testing several students, their parents and teachers who were showing flu-like symptoms. Israel has put two people under observation, while France and Brazil have also reported suspected cases.
Cordingley singled out plane travel as an easy way the virus could spread, noting that the WHO estimates that up to 500,000 people are aboard planes at any time.
Governments in Asia - with potent memories of SARS and bird flu outbreaks - heeded the warning amid global fears of a pandemic.
Singapore, Thailand, Japan, Indonesia, and the Philippines dusted off thermal scanners used during the 2003 SARS crisis and were checking for signs of fever among passengers arriving at airports from North America. South Korea and Indonesia introduced similar screening.
In Malaysia, health workers wearing face masks took the temperatures of passengers as they arrived from a flight from Los Angeles.
Officials said travelers with flu-like symptoms would be given detailed health checks.
Russia, Hong Kong and Taiwan said visitors returning from flu-affected areas with fevers would be quarantined.
Australian Health Minister Nicola Roxon said pilots on international flights would be required to file a report noting any flu-like symptoms for passengers aboard their planes before being allowed to land in Australia.
China said anyone experiencing flu-like symptoms within two weeks of arrival had to report to authorities.
But some officials cautioned the checks might not be sufficient.
The virus could move between people before any symptoms show up, said John Simon, a scientific adviser to Hong Kong's Center for Health Protection.
"Border guardings, thermal imaging will not detect much of this flu when it eventually comes through because a lot of people will be incubating," he said.
In Hong Kong, Thomas Tsang, controller for territory's Center for Health Protection, said the government and universities aim to develop a quick test for the new flu strain in a week or two that will return results in four to six hours, compared to existing tests that can take two or three days.
Swiss drug company Roche Holding AG said it could deliver its 3 million packages of Tamiflu anywhere in the world within 24 hours.
In New Zealand, Health Minister Tony Ryall said two students and a parent among a group of 15 who just came back from a class trip to Mexico had mild flu and were being tested for swine flu. On Sunday, officials said nine students and one teacher from a separate group that also were in Mexico "likely" have swine flu.
Results from a WHO-registered laboratory were expected within days.
All the New Zealand students and teachers along with their families had voluntarily quarantined themselves at home. In addition, Ryall said three small groups of returned travelers were being monitored after reporting flu symptoms following recent trips to North America. He gave no further details.
Prime Minister John Key said everyone showing flu symptoms was being treated with Tamiflu as a precaution. Other passengers and crew on the suspect flights were also being given the antiviral drug, said health department official Julia Peters.
China and Russia banned imports of pork and pork products from Mexico and three U.S. states that have reported cases of swine flu, and other governments were increasing their screening of pork imports.
Indonesia - the country hardest hit by bird flu - said Monday it was banning all pork imports to prevent swine fever infections.
Many governments issued travel warnings for Mexico, including Hong Kong and South Korea. Japan's largest tour agency, JTB Corp., suspended tours to Mexico at least through June 30.
Many measures recalled those taken across Asia during the severe acute respiratory syndrome epidemic and used more recently to monitor bird flu.
Drawing on their fight against SARS, experts in Hong Kong warned that swine flu seems harder to detect early and may spread faster.
On the Net:
WHO swine flu page: http://www.who.int/csr/disease/swineflu/en/index.html
Associated Press writers Fernando Sepe Jr. in Manila, Gillian Wong in Beijing, Frank Jordans in Geneva, Min Lee in Hong Kong, David Koop in Mexico City, Alex Kennedy in Singapore, Rohan Sullivan in Sydney, Jae Hee Suh in Seoul, Julia Zappei in Kuala Lumpur, Malaysia, Niniek Karmini in Jakarta, Indonesia and Rob Gillies in Toronto contributed to this report.
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