A total of 21 countries have officially reported 1,085 lab-confirmed human infection cases of the A/H1N1 flu virus to the World Health Organization (WHO) as of 18:00 GMT on Monday, the UN agency said in a latest update.

The largest numbers of cases were still reported from North American countries, notably Mexico and the United States, with 590 and 286 cases, respectively. Those cases include 26 deaths, 25 of which were from Mexico.

The following governments have reported laboratory-confirmed cases with no deaths: Canada (101), Austria (1), Hong Kong, China (1), Costa Rica (1), Colombia (1), Denmark (1), El Salvador (2), France (4), Germany (8), Ireland (1), Israel (4), Italy (2), the Netherlands (1), New Zealand (6), Portugal (1), the Republic of Korea (1), Spain (54), Switzerland (1) and Britain (18).

The WHO said on Monday that its pandemic alert level would remain at Phase 5 and it had no clear plan to raise it to Phase 6, the highest level which means a full pandemic is occurring, given the fact that there is still no sustained human-to-human infections of the new virus in regions out of North America.

Most of the infections in Europe and Asia were "travel-related cases," which means the virus has not taken root there, said Feiji Fukuda, the WHO's director for health security and environment.

But he stressed that it was "critical" for governments to maintain and strengthen their alert and surveillance, given the continued spread and the highly unpredictable behavior of the virus.

He expressed particular concern that the new virus might spread in the southern hemisphere, where the winter season is coming and flu viruses tend to be more active.

(Xinhua News Agency May 5, 2009)