A 2-month-old girl was diagnosed yesterday with H9N2 avian influenza, the fifth case in Hong Kong since 1999, the Centre for Health Protection (CHP) announced.

The locally born baby developed a cough, vomiting and runny nose, but no fever. She was admitted to Tuen Mun Hospital Dec 23 and discharged the next day.

Her parents took her back to Shenzhen, where she lives, but they consulted a local doctor soon after when she wasn't eating much.

She was re-admitted to Tuen Mun Hospital on Monday after tests indicated she had a high white blood-cell count.

Laboratory tests revealed yesterday that she was infected with the avian flu virus.

The infant remained in the hospital yesterday for further investigation. She is in stable condition, but doctors say the high white blood-cell count may be a sign of leukemia.

CHP Controller Thomas Tsang Ho-fai said the infant wasn't suspected of having avian flu on Dec 22 because she didn't have a fever.

He added that genetic sequencing, which takes one to two weeks, is being conducted to determine if the virus is wholly of avian origin.

Tsang emphasized that H9N2 is a less virulent strain of avian virus than the commonly known H5 influenza.

"Infection (of H9N2) in humans is rare and appears as a mild disease," Tsang said.

All four cases in the previous years were discovered in children, and they fully recovered.

The world's first human H9N2 infection was diagnosed in Hong Kong in 1999, in which two girls contracted the virus. Another two cases were diagnosed in 2003 and 2007. All four cases were caused by contact with live poultry.

Tsang said the strain of virus, predominant found in live poultry in Southern China, has been found in Hong Kong.

He suspected that the ill baby may have come in close contact with live poultry, but further investigation needs to be conducted with the Guangdong Health Department.

"As the girl was staying in Shenzhen for the whole incubation period, the Guangdong Health Department will look into her home surroundings," Tsang said, adding that the baby's family doesn't raise any poultry.

The family, which includes the child's parents and her grandmother, are asymptomatic and have been given Tamiflu as a preventative.

In addition to surveillance of the family, the CHP will trace people who have been in contact with the baby during her hospital stay to ensure they aren't infected.

Tsang said there's been no evidence that human transmission of the H9N2 virus is possible.

Associate Professor of Microbiology at the University of Hong Kong Ho Pak-leung said that the most efficient prevention is to maintain personal hygiene and avoid taking children to wet markets where they could come in contact with live poultry.

"As the weather (gets colder), there may be several cases of avian flu infection in the coming two to three months," Ho warned.

(HK Edition 12/31/2008 page1)