Experts fear bird flu mutation

Main Category: Bird Flu / Avian Flu
Also Included In: Flu / Cold / SARS
Article Date: 20 Jan 2004 - 0:00 PDT

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Public health experts around the world are wary about what could transpire from the ongoing spread of bird flu in many parts of Asia.

The origins of the infection are still unknown for certain cases, including one detected in a chicken farm in Japan.

If the virus mutated into a human influenza virus, it could wreak worldwide havoc, experts said.

'This can no longer be called mere influenza. The symptoms are like those of hemorrhagic fever,' said Masato Tashiro, head of the Department of Virology III of the National Institute of Infectious Disease (Japan).

Before he attended a meeting of a subpanel of the Health, Labor and Welfare Ministry's Health Sciences Council, Tashiro received autopsy reports on patients in Vietnam who died of infection from the bird flu virus.

Since autumn, 14 people have suffered serious pneumonia, 12 of whom died in Hanoi. Of the 12, four were confirmed to have been infected with the bird flu virus.

The reports contained a case in which a patient developed multiple organ failure in addition to symptoms in the lungs and digestive tract.

The patient's symptoms were similar to those of someone suffering from Ebola hemorrhagic fever, which is seen as one of the worst infectious diseases, and prompted Tashiro to make the remark.

Following the Vietnamese cases, the bird flu virus killed many chickens in central South Korea in December.

In Japan, the virus was identified in a chicken farm in Yamaguchi Prefecture this month. Though the type of the virus was different, an epidemic also appeared in Taiwan.

Currently, there are no reports of infection of the virus between humans, though infections from bird to human have been reported.

The World Health Organization issued a statement about the Vietnamese cases, saying mutation of the virus' genes, which makes infection among humans possible, had not been found.

But because in one case a parent and a child developed the disease at the same time, the possibility has not been ruled out.

To make matters worse, infection routes of the virus have not been identified.

In 1997, the bird flu virus caused infections from birds to humans in Hong Kong. At that time, 18 people were infected, six of whom died. As the fatality rate of conventional influenza viruses is said to be only 0.01 percent, this rate is worrying.

Medical experts now fear the worst development--the appearance of a new strain of the virus that can move from humans to humans.

The process may occur if bird and human viruses mutate inside pigs' bodies. The bird flu virus mutates when it interacts with a conventional human flu virus inside the body of a person infected with the two diseases at the same time, and the bird flu virus naturally mutates inside human body.

Strains of influenza that caused widespread epidemics in the past, such as the Spanish flu in 1918, which killed 40 million to 50 million people, also developed through similar processes.

Forecasts by the Health, Labor and Welfare Ministry's study team include a nightmarish scenario under which the emergency of a new type of influenza with the same infectious capacity and pathogenicity as those of the Spanish flu would lead to the infection of about 3 billion people and cause the deaths of more than 60 million around the world.

The government has established a committee of infectious disease experts to counter such a new strain of virus.

Measures to be taken include stockpiling antivirus medicines; developing preventive vaccines and preparing for mass-production of the vaccine; and deciding the order of priority in which people would be vaccinated.

A senior ministry official said: 'The appearance of a new strain of the virus is the start of a worldwide crisis. We need to take enough precautions before it is too late.'

Influenza patients suffer from high fever of 38 C or more. The disease is particularly risky for infants and elderly people with weaker immune systems. Preventive vaccines and antivirus medicines are effective.

Many of the massive outbreaks were caused by the Type A virus, which easily mutates. Some strains of influenza infect other animals, such as ducks, pigs, horses, seals and whales.