HK death may spark world flu epidemic

The death in Hong Kong of a three-year-old boy who was infected by a flu virus never seen before in humans has triggered a worldwide alert that a new global flu pandemic may be imminent. The World Health Organisation sent a team of scientists to Hong Kong last week to assist local experts who have been searching for the source of the infection. The scientists will try to establish whether other people in southern China have been infected with the strain.

The boy, who has not been identified, died of a virus previously seen only in birds. Medical experts say that because it is a new virus to which humans have no immunity, it could spread rapidly, infecting millions around the world. Although flu is normally a mild illness, every couple of decades the virus undergoes a mutation, producing a strain to which no one has immunity, turning it into a deadly disease. Three previous flu pandemics have occurred this century, killing millions of people, and all involved viruses that originated in birds. The 1918 pandemic, in which 20 million died, was followed by outbreaks in 1957 and 1968. Virologists say the next one is overdue.

The seriousness of the threat is underlined by the decision of the Government to issue new guidance to health authorities and trusts last March instructing them how to prepare for the next pandemic. The document, Multiphase Contingency Plan for Pandemic Influenza, says the aim is to reduce death and disease and enable the National Health Service "to cope with large numbers of people ill and dying". It says all non-urgent admissions to hospitals may have to be cancelled and hospital plans "must include mortuary arrangements in the event of a large number of deaths".

The document, which received no publicity because it was issued two weeks before the general election, says three conditions suggest a pandemic is imminent: the emergence of a new strain of virus (in the Hong Kong boy); a high proportion of susceptible people in the population with no immunity; and evidence that the new strain can spread and cause disease. The first two conditions are met by the Kong Kong case, but experts are waiting to see if further cases of infection with the same virus emerge, proving that it can spread among humans.

Dr Alan Hay, director of the World Health Organisation's influenza monitoring centre at the National Institute of Medical Research in north London, said the boy died on 20 May, and virologists identified the virus that infected him the following day as H5N1. "That is quite unique. Our concern was whether it was a one-off or representative of something more sinister. We were worried."

The virus that infected the boy was responsible for an outbreak of flu in chickens in Hong Kong in March and April. But there is no evidence that either the child or his parents had contact with chickens. Dr Hay said that as the weeks passed and no new cases apparently emerged, it looked less likely that this was the start of the next pandemic.