An 8-year-old girl from northern Thailand has tested positive for bird flu, becoming the fourth person in the kingdom to be infected in the latest outbreak.

The girl, from Petchabun province, was hospitalized last week with flu-like symptoms and is now listed in poor condition.

Health authorities say she is believed to have contracted the disease from infected birds.

Thailand went on high alert last week when it was reported that an earlier bird flu victim died, probably after contracting the virus from her daughter. Such human-to-human transmission could mean the virus has mutated into a more contagious form, but this has not been confirmed. The dead woman's sister is being treated in a hospital in the northern province of Khamphaeng Phet.