By Sybille de La Hamaide PARIS, May 31 (Reuters) - The spread of bird flu may be waning but the world must keep up its guard against the threat of a human influenza pandemic, which is almost certain in the longer term, senior health experts said on Thursday. Senior international bird flu experts meeting at the Anti-Avian Influenza conference in Paris said the rise in the rise in the number of cases both in birds and in humans had slackened, especially since the start of this year. "The disease is weakening. It does not mean it could not come back but there is something happening," Bernard Vallat, head of the World Animal Health Organisation (OIE), told Reuters. The highly pathogenic H5N1 bird flu strain that appeared in Asia at the end of 2003 has infected 309 people around the globe, killing 187. Data for the first half of 2007 might indicate the disease was coming closer to the end of a cycle, Vallat said, but worries remained over Indonesia, Nigeria and Egypt. "If the those last pockets were crushed it would be much more reassuring," he said. FLU PANDEMIC ALMOST CERTAIN "The number of human cases continues to increase but at a slower pace," Milan Brahmbhatt, a World Bank official, said. However, fears remained that the disease could mutate into a type that passed easily between people, triggering a global pandemic in which tens of millions might die, experts said. Keiji Fukuda, head of the WHO's global influenza programme, said a pandemic could originate from the bird flu virus but not necessarily. "If you look at the H5N1 bird flu virus, we don't know whether it will be the one that will develop," he said. "So the conclusion is that preparedness for a human pandemic remains as high a priority as it has ever been."
