Pandemic flu spreading with Asian monsoon season-WHO

* Virus spreading widely in India, Thailand and Vietnam

* Spread seems to have peaked in parts of s. hemisphere

* Official death toll stands at 1,462 worldwide

By Stephanie Nebehay

GENEVA, Aug 11 (Reuters) - H1N1 pandemic flu is spreading in India, Thailand and Vietnam with the onset of Asia's monsoon season, the World Health Organisation (WHO) said on Tuesday.

But transmission of the new virus appears to have peaked in parts of the southern hemisphere including Argentina, Chile, Australia and New Zealand, the United Nations agency said.

Some 177,457 cases of the virus commonly known as swine flu, including 1,462 deaths, have been officially reported worldwide as of Aug. 6, but the true number of infections is certainly much higher, it said.

"We are seeing the spread of the pandemic being reported in many of the tropic countries. And in Asia, particularly in India Thailand and Vietnam. Also we're getting into the monsoon season in those countries at this time," WHO spokeswoman Aphaluck Bhatiasevi told a news briefing in Geneva.

The regular influenza season has begun in the three countries, coinciding with the monsoon season, and both H1N1 and seasonal flu are being detected, she said.

"Thailand has reported widespread influenza-like illness and it is increasing. In Vietnam and India there is an increasing trend but it is not yet widespread," Bhatiasevi told Reuters.

India's health ministry last week confirmed the country's first death from H1N1, a 14-year-old girl.

The H1N1 flu outbreak, declared a pandemic on June 11, has spread around the world since emerging in April and could eventually affect 2 billion people, according to WHO estimates. "In temperate areas of the southern hemisphere -- Argentina, Chile, Australia and New Zealand -- pandemic virus transmission appears to have peaked and is now on the decline in areas previously affected," WHO spokeswoman Fadela Chaib told reporters.

Countries are now only obliged to report their first confirmed cases to WHO, which says there is no longer any point to counting each infection as the virus is unstoppable.

Fears that the strain could become resistant to the anti-viral drug Tamiflu (ROG.VX) (GILD.O) have underscored the need to get vaccines to market quickly.

Leading flu vaccine makers include Sanofi-Aventis (SASY.PA), GlaxoSmithKline (GSK.L), Novartis (NOVN.VX), Baxter (BAX.N), CSL (CSL.AX) and Solvay (SOLB.BR).

The WHO said last week that the first vaccines should be approved and ready to use next month. [ID:nL6332419] (Editing by Jonathan Lynn)