Preliminary tests have confirmed that a 12-year-old girl who died was infected with the deadly H5N1 strain of bird flu, raising Turkey's death toll to four, health officials said Monday.

Fatma Ozcan died Sunday in the eastern city of Van, but initial tests had been negative for H5N1. The Health Ministry ordered more tests after her 5-year-old brother, Muhammet, tested positive. Officials said those confirmed her infection, raising the number of human cases in the country to 20.

Five patients had been discharged from hospitals as of Monday afternoon, leaving only 11 still in treatment, the ministry said.

Authorities hastily buried Fatma on Sunday evening, wrapping her in a special body bag to contain any virus, following a quick prayer by torchlight at a snow-covered cemetery. She was from Dogubayazit — where three siblings died of bird flu 1 1/2 weeks earlier.

Her brother was being treated for fever and a light lung infection, officials said.

A new viral specimen that had been taken from the girl's lungs was analyzed at a laboratory in Ankara, Hurrem Bodur, an infectious disease expert at Ankara University, told private NTV television.

At least 77 others in east and south Asia have died since the virus first surfaced there in 2003, the World Health Organization says. The WHO has confirmed only two of the four Turkish deaths, but it has been tracking the outbreak closely to determine whether the virus was changing.

Experts are concerned that the virus could mutate into a form that would easily spread from human to human, triggering a pandemic capable of killing millions. Turkish health experts, however, have said all 20 cases in Turkey appeared to have involved people who either touched or played with infected birds. The WHO has said it had no evidence of person-to-person infection.

The government said Monday that it has destroyed 764,000 fowl in its fight to contain the bird flu outbreak, with the slaughter focused on the 29 of Turkey's 81 provinces where bird flu in fowl was either confirmed or suspected.

As the Cabinet met to discuss further action, authorities on Monday banned the transport of all birds and hoofed animals, except race horses, as a precaution.

Authorities also were trying to save some of the fowl. On Sunday, people living in remote villages in central Turkey began to disinfect their chicken coops after the Agriculture Ministry distributed special kits.