Who on alert as flu season nears

The World Health Organization (WHO) is urging the planet to brace itself for a second wave of the swine flu pandemic as the heavily populated northern hemisphere edges toward the cooler season when flu thrives.

"The WHO is still mobilized and worried," spokesman Gregory Hartl says as the global health watchdog kept an anxious eye on some "mysterious" patterns of illness associated with the new H1N1 virus that appeared in April.

Influenza traditionally surges to its peak during the northern autumn and winter.