Hong Kong has confirmed that a 59-year old woman who recently travelled to mainland China has bird flu, the first human case in the special administrative region in seven years.

Hong Kong had the world’s first major bird flu outbreak in humans in 1997, where it killed six people, infected 12 others, and resulted in the culling of millions of birds. The last case recorded in the region was in 2003.

The 59-year old woman is in a serious condition in hospital, health officials announced on Thursday.

She was first diagnosed with pneumonia until tests revealed she has a variant of avian influenza, Influenza A (H5).

A spokesman for the Hong Kong Department of Health told AFP news agency that the government has raised Hong Kong’s bird flu alert status to “serious” to signify there is a “high risk” of the potentially fatal disease spreading to other people.

Meanwhile health officials are trying to establish whether she caught the virus in Hong Kong or elsewhere. They are seeking to trace her movements and the people she came in contact with.

The woman travelled to mainland China with her husband and daughter on 23 October and returned on 1 November, and during that time she did not come into contact with live poultry and did not visit farms, according to a statement from the Hong Kong Department of Health.

The woman is thought to have visited Shanghai, Hangzhou and Nanjing, said a BBC news report.

The woman’s symptoms started with a runny nose the day after her return on 2 November, and this developed into a fever and cough three days later. She sought help from the Accident and Emergency Department of Tuen Mun Hospital (TMH) on 12 November, and was admitted two days later when her symptoms developed into a persistent fever and productive cough with blood-stained sputum, said the statement.

At first the patient was diagnosed with pneumonia, but tests on mucus samples taken via a tube inserted into the nostrils to reach the top part of the throat (nasopharyngeal aspirate, this traps infected cells as well as secretions) showed positive for Influenza A (H5).

The patient’s 60-year old husband also had a runny nose and productive cough, but has since recovered.

A spokesman for the Centre for Health Protection of Hong Kong’s Department of Health said they were still doing tests on the virus.

In the meantime they have “stepped up surveillance by testing all severe pneumonia cases for H5,” he said, and officials are “closely liaising with the Mainland authorities and the Hospital Authority to monitor the situation”.

The spokesman said the best way to prevent being infected by the flu was to build up body resistance by keeping to a healthy diet, taking good exercise and rest; keeping rooms well ventilated also helps prevent spread of respiratory tract infection, he added.

People should also avoid touching poultry and birds, and if they do, they should wash their hands thoroughly with soap and water.

“Members of the public should seek medical consultation promptly if they develop influenza-like illness,” he said.

Since the first outbreak of H5N1 bird flu in humans in 1997, there has been no case of it posing a major global threat because it cannot pass easily from human to human.

According to the World Health Organization (WHO), since 2003, there have been 500 laboratory confirmed cases of H5N1 bird flu in humans worldwide, 302 of which were fatal.

The fear, which many experts believe is not groundless, is that the virus will adapt and start spreading among humans and trigger a global flu pandemic of deadly proportions.

There are two ways the virus can adapt and become transmissible among humans. The first way is through “reassortment” where genes from bird viruses exchange with those of human viruses during co-infection in a human or even a pig.

The second way is a more gradual process of adaptive mutation, where the virus becomes more able to bind to human cells.

The first mechanism would result in an explosion of cases and rapid transmission. The second method, because it requires repeated cases of human infection, would probably give us more time to develop defenses, if detected early, according to the WHO.

Hong Kong’s health chief York Chow said on Wednesday that so far there was no evidence in this case that the virus has passed from human to human.

He said they were concentrating their efforts on poultry as the origin of the infection, but they will be focusing on people who the woman came into contact with as well. He said while the chances are that she most likely contracted the illness on the mainland, they could not rule out that the source is in Hong Kong.

In the meantime the Hong Kong government has raised the alert level to serious, under its Preparedness Plan for influenza pandemic, and a telephone hotline has been set up on 2125 1111 for public enquiries.

Sources: Hong Kong Department of Health Press Release, AFP, BBC News, WHO.

Written by: Catharine Paddock, PhD