The Thai Public Health Ministry confirmed yesterday that a 20-year-old-woman has returned from the US infected with type A (H1N1) influenza - the tenth Thai to fall victim to the flu virus that has already hit 69 countries, causing 125 deaths.

The woman is undergoing hospital treatment with the antiviral oseltamivir drug and will receive it for five consecutive days, Public Health Minister Witthaya Kaewparadai said.

The Ministry has sent its Surveillance and Rapid Response Team (SRRT) to monitor four people who've had close contact with the woman, he said.

The first human to human transmission of the new flu within the country was reported to the Ministry after a 19-year-old man contracted the disease from his mother who returned from the US on May 25.

Another victim, a 20-year-old woman whose identify was withheld, had been in America for study and work since March and returned to Thailand on June 5. She developed flu-like symptoms such as headache, coughing, sore throat, runny nose and was admitted to hospital in Bangkok.

Her samples were tested at the Department of Medical Science's laboratory and showed positive.

" The patient has now recovered after receiving the antiviral drug for five days," the Ministry's permanent secretary, Dr Prat Boonyawongvirot said.

Four people who had close contact with her were instructed to stay at home for three days but have shown no signs of the flu.

Meanwhile, a 29-year-old businessman, confirmed as the ninth H1N1 influenza case after returning from the US, has recovered after intensive treatment. People who've had close contact with him are also being closely monitored.

Public Health Ministry deputy permanent-secretary, Dr Paijit Warachit warned the new flu virus could combine with the seasonal influenza virus and mutate into a form that spreads easily among the community.

Dr Tawee Chotpitayasunondha, a health expert, has expressed concern over the welcoming ceremony for freshmen at some educational institutes . Senior students force freshmen to keep candy in their mouths and pass the same candy by mouth to other freshmen.

He said such bad hygiene would spread communicable disease, such as the influenza virus.

"They should stop the custom as it could cause direct disease infection," Tawee said.