Reason to be fearful over bird flu

On September 2 last year, an 11-year-old girl was taken by her aunt to a clinic in the village in Thailand where she lived. She had a fever, cough and sore throat. Five days later she was worse, suffering breathlessness, and was admitted to hospital.

The girl's mother, who lived in a distant city, came to be with her daughter and nursed her for at least 16 hours over September 7 and 8. By now, the girl was critically ill and was transferred to a provincial hospital where she was placed on a ventilator. She died three hours later.

Blood tests showed the girl was a victim of avian flu, a virus that has decimated poultry flocks in Southeast Asia in the worst epidemic in living memory. Chickens kept by her aunt became sick and died a few days before the girl became ill. She had played where they lived, under the house.

But what made her case unique was that, three days after her death, the mother fell ill with the same symptoms, went rapidly downhill, and died on September 20. Crucially, she had no contact with poultry, but the cause of her death was confirmed as avian flu. Sequencing of the virus showed it was the same strain. The girl's aunt also contracted it, but recovered.

Scientists who examined the family cluster say it provides the clearest evidence so far of what doctors have long feared - that the lethal avian-flu virus can be passed between people.

In a report on the case published in the online version of the New England Journal of Medicine last week, scientists from Thailand, the United States and the World Health Organisation in Geneva say the world has been given "unprecedented warning" of a pandemic, adding: "We need to put up safeguards while the storm is gathering."

There have been probable cases of human-to-human transmission before but this is the first in which the person infected - the mother - contracted severe illness and died. It proves the virus can be passed from person to person without losing its lethality.

The strain of avian flu circulating in Southeast Asia is twice as lethal to humans as smallpox, but has not yet acquired the capacity to spread with the ease and rapidity of human flu. The fear now is that it is only a matter of time before avian flu "reassorts" with human flu to create a pandemic strain.

Should that happen it would become the 21st century's plague. The virus poses the greatest potential threat to the world, greater by far than the threat from bio-terrorism, natural disaster or nuclear accident. Three times in the last century - in 1918, 1957 and 1968 - avian flu jumped to humans, mutated and spread round the globe, claiming millions of lives.

The world has been on high alert for the next pandemic of avian flu since 1997, when an outbreak of the H5N1 strain among poultry in Hong Kong caused panic in the city and led to the slaughter of more than a million chickens.

There have been several outbreaks among humans since as avian flu has spread, devastating poultry flocks in Southeast Asia and infecting ducks, pigs, wild birds and even a snow leopard in a zoo.

Avian flu causes the same symptoms as ordinary flu in its early stages but it can lead rapidly to secondary symptoms, such as pneumonia, resulting in death.

With avian flu spreading unchecked through the bird population in Southeast Asia, the number of people exposed to it grows and the chances increase of a lethal mutant form developing.

The H5N1 virus that emerged in 1997 has already gone through many reassortment events and several genotypes have emerged. The currently circulating one, Z, appears to be more lethal to humans and researchers say that the evidence points towards its becoming more efficient in transmitting to humans. 

The virus is transmitted through the air, as infected people breathe, and by touch. It would take only one infected person on an aircraft to put all other passengers at risk. Children are the most infectious because they shed the greatest amount of virus.

Last year, avian flu infected 44 humans and caused 32 deaths in Vietnam and Thailand, a death rate of 72 per cent. More than 200 million birds were slaughtered across the region. The WHO warned that the present situation resembled that which led to the 1918 pandemic that probably caused more than 40 million deaths, it said.

The latest reports say two Vietnamese girls died of avian influenza last weekend, and the disease may have claimed its first human victim in Cambodia. A 13-year-old girl and a 10-year-old girl became the 11th and 12th people to die of H5N1 avian flu in Vietnam since late December.

The 13-year-old girl, who lived in Dong Thap province in southern Vietnam, died on January 29, according to an Agence France-Presse (AFP) report. Her mother died on January 21. AFP quoted state media reports saying the girl and her mother had slaughtered an infected duck for a meal.

A SECOND family cluster in Vietnam, involving three brothers in their 40s, two of whom caught the virus, is under intense investigation because of suspicions that there may have been human-to-human transmission. One of the brothers died.

Some countries are preparing for the worst. Last August, the US Government announced measures to protect the population in the event of a pandemic, including the closure of schools, a ban on travel and the quarantining of international visitors. Americans would be advised to work from home, stop shaking hands and wear masks in public.

The British health department has drawn up a similar plan.

A vaccine is not included in either country's plans. Although flu vaccines exist, they would be useless against an H5N1 strain. The vaccine, which is grown in hen's eggs, must be matched precisely to the virus to be effective. It would take at least six months from the moment a pandemic strain was identified to produce one. By then it would be too late.

The alternative to a vaccine is anti-viral drugs. Unlike vaccines, these can be used against any strain of flu. Although they have limited effect against the illness, they help to prevent secondary complications such as pneumonia, and reduce infectivity, cutting the rate of spread.

Some countries have begun stockpiling the anti-viral drug, Tamiflu (made by Roche). A spokeswoman for Roche UK said Denmark, France, Korea, the Netherlands, Norway and the US had placed orders for Tamiflu but negotiations were still ongoing with Britain.

Some experts believe the time for dithering is over. Sir John Skehel, director of the British National Institute for Medical Research and a leading authority on flu, said last week the situation was alarming.

"We are looking at a 70 per cent death rate for this virus. Once you have a drug that is effective against influenza, it changes completely how you respond to a potential epidemic.

- INDEPENDENT