Hong Kong health authorities are on alert following the discovery of the city's first human case of bird flu in seven years

Officials, meanwhile, are still struggling to determine if the 59-year-old woman who tested positive for Influenza A (H5), a variant of the avian flu, contracted the disease within the city.

In a press conference Thursday, York Chow, the secretary for food and health, said the risk of avian flu in Hong Kong is 'not significantly higher than before.' Nonetheless, he said all public hospitals are operating at the serious response level under the government's preparedness plan for an influenza pandemic, requiring visitors to wear surgical masks, limiting the number of visitors and shortening visiting hours.

The Center for Health Protection is also testing all severe pneumonia cases for the bird flu. The city's last case of avian flu in humans was in 2003. In 1997, Hong Kong was home to the world's first major outbreak in humans, when six people died from the virus' mutation.

The government will also increase testing of chickens that cross the border with mainland China. In addition, the Agriculture, Fisheries and Conservation Department will inspect 30 Hong Kong farms and obtain samples for further testing.

The victim, currently in serious condition at Princess Margaret Hospital, traveled in mainland China for 10 days before returning to Hong Kong Nov. 1. She developed her first symptom, a runny nose, the next day.