An 18-year-old girl has died of bird flu in southern Vietnam and the first confirmed human infection in the country’s north has raised concerns about possible human-to-human transmission of the virus.

The girl died in a Ho Chi Minh City hospital on Wednesday after battling the highly virulent H5N1 strain for nearly two weeks since she was hospitalized on Jan. 6 from the southern province of Tien Giang, the Tuoi Tre (Youth) newspaper said.

Her death takes the Asian bird flu death toll to 38 - 26 in Vietnam and 12 in Thailand.

In the latest wave of outbreaks, seven Vietnamese people have been confirmed as infected by bird flu. Six of them have died and all the deaths are in the south.

The latest confirmed case of H5N1 infection was a 42-year-old man in the capital, Hanoi, which has raised fears the virus could jump from person to person, state-run Vietnam Television said late on Wednesday.

It said the man had had no contact with sick poultry but that he went to take care of his older brother in a Hanoi hospital earlier this month. The older man died of a respiratory illness on Jan. 9, although tests showed he did not have bird flu.

“The Ministry of Health is conducting epidemiological investigations into these cases and WHO will keep in close contact with the Ministry of Health over the progress and findings of these investigations,” the U.N.‘s World Health Organization (WHO) said in a statement on its Web site (http://www.who.int).

What the WHO fears most is that the virus could mutate if - and there is no evidence it has - it got into an animal capable of hosting a human flu virus.

That would probably be a pig, and if the H5N1 were to merge with a human flu virus, it could produce a strain capable of sweeping through a human population without immunity, the WHO says. Millions could die worldwide.

The H5N1 virus already kills a high proportion of the people it infects.

More human deaths are feared. The WHO said in Geneva on Tuesday it had been told by Vietnam that up to 10 more suspected human cases were under investigation.

State media said at least nine cases were now suspected of contracting bird flu, including two who were hospitalized in Ho Chi Minh City from the southern province of Dong Nai on Wednesday. Four are in Hanoi, two of them in critical condition and on a respirator.