Swine flu is a "sneaky virus" that is likely to keep spreading to new parts of the world and within countries already affected, the head of the World Health Organization said Friday.
At least 42 countries have confirmed cases of the disease, which has sickened 11,168 people and caused 86 deaths, most of them in North America.
'[E]ven the best-laid plans need to be fluid and flexible when a new virus emerges and starts changing the rules.'вЂ" Margaret Chan
"This is a subtle, sneaky virus," WHO's director-general Margaret Chan said at the close of the global body's annual assembly in Geneva.
"It does not announce its presence or arrival in a new country with a sudden explosion of patients seeking medical care or requiring hospitalization."
Countries need to increase their laboratory testing capacity to detect and follow the virus, whose march around the world was virtually unstoppable, she said.
"We expect it to continue to spread to new countries and continue to spread within countries already affected," Chan said.
Discussions about swine flu took up much of the WHO's five-day meeting in Geneva, which was shortened from two weeks to allow government ministers to spend more time overseeing pandemic preparations at home.
Chan heeded the call of many of WHO's 193 member states to reconsider the agency's criteria for raising the pandemic alert to Phase 6 вЂ" its highest alert level вЂ" to avoid unnecessary panic and economic disruption.
The WHO's alert currently stands at Phase 5, meaning a pandemic is "imminent."
Chan indicated she was going along with the countries that had urged caution in declaring a pandemic, saying that "even the best-laid plans need to be fluid and flexible when a new virus emerges and starts changing the rules."
Pandemic criteria
With increasing numbers of cases in Japan and Europe, the world is inching closer to meeting WHO's criteria for a pandemic: ongoing spread in at least two world regions.
Chan conceded that phases 5 and 6 are "virtually identical in terms of the actions they launch." She said she would consult the WHO's emergency flu committee before declaring a global outbreak.
Countries taking part in the Geneva meeting agreed Friday to put off efforts to finalize a deal on sharing flu virus samples, instead instructing Chan to find a solution by early next year.
Developing countries lobbied hard to ensure they would benefit from any drugs created using their samples.
Against that, the United States and the European Union called for samples to be shared without restriction, arguing that this was in the best interest of science and global efforts to combat disease.
Both sides agreed Chan should form a task force to investigate unresolved questions, including whether countries should have to share samples and resulting drugs could be patented. They also want the task force to consider whether doses of any new pandemic flu vaccine should be reserved for developing countries, and to report back to members in January with recommendations.
WHO said confirmed cases of the new virus вЂ" termed A/H1N1 вЂ" increased by 134 since Thursday.
The U.S. has reported the most laboratory-confirmed cases with 5,764 вЂ" an increase of 54 cases вЂ" followed by Mexico with 3,892. It was unclear, however, if the increases reflected only a higher infection rate, or could also be partly explained by the fact that there has been more avid testing in those countries.
Also on Thursday, Mexico City lowered its swine flu alert level from yellow to green, and the mayor said "we can relax" now that there have been no new infections for a week.
Japan raised its tally by 35 to 294, while in Chile the caseload rose by 19 to 24.
Overall there have been 86 deaths linked to swine flu.
