Preliminary tests Tuesday showed another person in Turkey has tested positive for a deadly strain of bird flu, raising the number in the country to 15, a Health Ministry official said. The number of people hospitalized with symptoms also climbed to about 70, officials said.

The 15th positive test for the deadly H5N1 strain of bird flu — a person hospitalized in the central Anatolian city of Sivas — was disclosed by the Health Ministry official who spoke to The Associated Press on condition of because she was not authorized to speak to the media. Three people died last week, but only two of those cases were confirmed to have tested positive.

Turkey, meanwhile, stepped up an awareness campaign to combat the bird flu outbreak, with imams warning about the danger through minaret loudspeakers and authorities distributing leaflets urging people not to contact fowl.

The United Nations' health agency so far has confirmed only four of those cases as H5N1, but it warned that each new positive test increased the virus' chances for mutating into a form that could pass from human to human and spark a pandemic.

"The more humans infected with the avian virus, the more chance it has to adapt," said Guenael Rodier, a senior World Health Organization official for communicable diseases. "We may be playing with fire."

U.N. and Turkish authorities urged citizens to follow health guidelines for working with poultry, and to prevent children from coming into contact with dead birds.

Authorities distributed leaflets in eastern parts of the country, which has been most affected by the outbreak, cautioning people not to touch the fowl. TV broadcasts urged people to wash their hands after contacting poultry. Imams also issued warnings through mosque loudspeakers in the western town of Yesilova in Burdur province, the Anatolia news agency reported.

The WHO on Monday raised its own count of preliminary positive cases in Turkey to 10, but maintained its confirmed count at four "because we don't have the complete laboratory information" on the others, WHO spokeswoman Maria Cheng said in Geneva.

Gulsen Yesilirmak, who was hospitalized in Sivas, told private a Turkish television station from her hospital bed that she fell sick after throwing out dead chickens from a coop.

"I threw out one and another died and I threw out that, too, then I got sick. ... I sat down exhausted and I had headache," said Yesilirmak, struggling to breathe behind a protective mask. Her eyes were red.

Doctors were also monitoring her two children at the hospital as a precaution, according to a Turkish media report.

Meanwhile, more than a dozen people were admitted to hospitals across Turkey with flu-like symptoms Tuesday, including four in the western town of Aydin, where the virus in fowl was detected a day earlier in the Aegean resort town of Kusadasi, just across from the Greek island of Samos in the Aegean Sea.

Turkish authorities already have hospitalized more than 60 people with flu-like symptoms who had come into close contact with fowl.

On Tuesday, workers continued killing birds across the country as Turks observed the beginning of the Eid al-Adha, the most important holiday of the Islamic year. They prepared to sacrifice sheep, rams, bulls or camels as part of the commemoration.

Some Turks were worried that sacrificing animals could be dangerous, but health authorities tried to allay their fears, saying there was no risk.

Turkish authorities have killed some 110,000 fowl, including around 3,000 in Istanbul, to combat the outbreak, reports said Tuesday. Authorities also have banned the sale of fowl in open markets and even the sale of eggs in some areas in hopes of containing the virus.

Health officials are watching the disease's spread and development, while WHO labs are testing for genetic changes in the virus that could allow it to be transmitted between humans and spark a pandemic.

The outbreaks have been occurring in Turkey because of the close interaction here between humans and animals, which must be minimized, Rodier said. "The front line between children and animals, particularly backyard poultry, is too large," he said.

Of the WHO's four confirmed cases, all involved children who were in close contact with fowl, suggesting they were likely infected directly by the birds.

Those four included two siblings who died last week in the eastern city of Van — the first confirmed bird flu fatalities outside eastern Asia, where 74 people have been killed by H5N1 since 2003. A third sibling also died in Van, but preliminary tests in Turkey could not determine whether she was positive and a WHO lab has yet to confirm it was the H5N1 strain.

A doctor in Van said the siblings likely had been infected while playing with the heads of dead chickens. Several other children had similar stories.

Health Minister Recep Akdag said he was confident Turkey would overcome the outbreak, but warned there would continue to be a risk for years because the country lies on a major path for migratory birds.

Akdag urged people to abandon raising poultry in backyards. "If as a community we take the necessary measures and educate (people), we can in a short period of time combat this," he said.