Health authorities went on high alert Tuesday following Iraq's first reported case of the deadly bird flu virus, killing hundreds of thousands of birds and warning farmers across the country to inspect their flocks.

Five mobile hospitals with special equipment were due to arrive in northern Iraq later Tuesday, according to Health Minister Abdel Mutalib Mohammed. A 20-mile security cordon will be placed around the village where the disease appeared, he added.

The measures followed Monday's announcement that a 15-year-old girl from northern Iraq who died Jan. 17 had contracted the deadly H5N1 strain of bird flu. It was the first confirmed human case of H5N1 in the country.

The prospect of a bird flu outbreak in Iraq is alarming because it is gripped by armed insurgency and lacks the resources of other governments in the region. Government institutions, however, are most effective in the Kurdish-run area where the girl lived.

The United States has offered assistance to Iraqi authorities to help deal with the outbreak, while a World Health Organization team of epidemiologists and clinicians was expected to arrive later in the week to start tests.

"We are working with the government of Iraq and the World Health Organization to ensure that the necessary support for diagnosis and treatment of avian influenza is available as needed," U.S. Embassy spokeswoman Sylvia Blackwood said.

WHO spokesman Dick Thompson said health authorities are also investigating two more possible bird flue cases — the girl's uncle who died Jan. 27 and a 54-year-old woman from the same region who has been hospitalized.

Iraqi authorities believe the girl most likely contracted the disease from migratory birds that passed it onto domestic birds in her hometown of Raniya, U.S. Embassy health attache Jon Bowersox said.

Raniya is just north of a reservoir that is a stopover for migratory birds from bordering Turkey heading south through Iraq's southern marshlands, onto Kuwait and further to South Africa, Bowersox said. At least 21 cases of bird flu have been recorded in Turkey, raising fears the virus may have moved south.

Experts fear the virus could mutate into a form spread easily among humans, triggering a pandemic capable of killing millions. A total of 85 people had died of the disease worldwide before the Iraq case was reported, according to WHO figures.

Bowersox said detecting sick and dying birds and their actual culling will be among the most difficult tasks faced by Iraqi authorities.

More than half a million domestic birds have been killed so far by about 50 health teams working throughout northern Iraq, said Agricultural Ministry official Tahsin Namiq.

However, the announcement of H5N1's arrival appeared to cause little concern among many Iraqis hardened by years of death and war. Many people simply didn't believe the reports.

"We will go on eating chickens. There is no bird flu in Iraq. Such news is false," said Salah Abdul-Hussein, a poultry dealer in Baghdad's Sadr City neighborhood.

But some reacted quickly to the report by doing their own culling.

"When I heard about bird flu being found in Iraq I hurried to the veterinarian who came to my home and we both burnt my pigeons," said Haitham Saham, a coffee shop owner who has been breeding birds since 1995 in Sadr City.

Following Monday's announcement, health officials started implementing measures to combat any spread of the outbreak.

Farmers killed thousands of chickens and ducks in Sarkathan, a village about four miles north of Raniya, the town where the teenage victim, Shangen Abdul Qader, lived. Culling teams continued working Tuesday in villages about 12 miles west of Raniya.

In the northern city of Mosul, health teams were visiting restaurants, cafes and farms to inspect poultry and hygiene, while hospitals have been put on alert to receive possible bird flu cases. Authorities also said they would spend about $680,000 to build a mobile hospital in the area where Qader died.

In Saddam Hussein's hometown of Tikrit, local Agriculture Ministry official Thamir Ahmed said poultry farmers needed to provide bird samples to veterinarians or their farms would be closed.

Tikrit veterinarian Dr. Abdul Hussein said there were no suspicious cases in the city, about 80 miles north of Baghdad, but if there were, authorities were poorly equipped to cope with it.

"If it happens, God forbid, we do not have any equipment or necessary tools to control the spread of this disease," Hussein said.

In the south-central city of Kut, local health chief Dr. Falah al-Bermani said authorities had been preparing for three months for the eventuality of an outbreak, and have been contacting farmers since Monday's confirmation.

Health officials do not yet know how the Iraqi girl contracted the virus, but just north of Raniya is a reservoir used as a stopover by migratory birds from Turkey, where at least 21 cases of H5N1 have been recorded. Four children in Turkey have died.

The disease has not proved as deadly in Turkey as in East Asia — where more than half of those infected have died — but U.N. experts warned that does not mean the virus was becoming less dangerous.

Still, the risk of the virus spreading may not increase unless there are big clusters of cases in Turkey or other countries, indicating that the strain has become more virulent, said Angus Nicoll, of the European Center for Disease Control and Prevention.