Health

Bird Flu Strain Traced to Poultry, Not Migratory Birds, Spreads to Taiwan

| by Denise A Justin
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Taiwan's Health Department announced on April 24 that a 53-year-old businessman contracted the H7N9 bird flu while travelling in China and is hospitalized at the Hoping hospital in Taipeiin serious condition.

The H7N9 flu strain has now infected 108 people in China since it was first detected in March, according to the Geneva-based World Health Organization (WHO.) First detected in Shanghai, the virus has also claimed victims in Beijing and five other provinces.

Scientists are describing this strain as “one of the most lethal influenza viruses yet” and have determined that it transmits more easily from birds to humans than prior strains. Testing has shown it is a 'triple reassortant' virus with a mixture of genes from three other flu strains found in birds in Asia, according to health experts.

The sudden death of 122 dogs and 410 pigs last week in a village in Henan province also caused concern over possible inter-species transmission. The possibility of chemical toxins in the water or air is being investigated; but, Chinese officials admit that no poisonous gases have been found in tests on the air around the village and its drinking water has met quality standards, according to a report on Henan’s official news site.

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The first H7N9 case in a human outside eastern Chinawas reported by Reuters on April 12, when it was confirmed to have infected a seven-year-old child in Beijing. Posters on how to (hopefully) avoid contracting the deadly disease are now visible in public place in the capital city, and residents are covering their nose and mouth with face masks when they are conducting normal business activities.

The various strains of bird flu have killed hundreds of people since 2003, mostly in Asia, and thousands of animals have been destroyed over fear of animal-to-human transmission.

Although experts are still puzzled at exactly how people are being infected, they see no evidence so far of “sustained transmission between people,”according to the Daily Mail report.

After an international team of scientists led by WHO and the Chinese government conducted a five-day investigation in China, they admitted they are no closer to determining whether the virus might become transmissible between humans.

The alarming H1N1 'swine flu' of 2009/2010, was a mixture of mammal and bird flu. Hybrid strains are more likely to be milder because mammalian flu tends to make people less severely ill than bird flu, such as the current H7N9 strain, Keiji Fukada, WHO’s Assistant Director General for Health Safety explained.

The medical team, which began its investigation in China last week, said a perplexing issue in tracking H7N9 is the absence of visible illness in poultry. But Fukuda stressed that, since the investigation has just begun, “we may be seeing the most serious infections at this point.” Based on the evidence, 'this virus is more easily transmissible from poultry to humans than H5N1,” he said.

The initial cases of H7N9 in and around Shanghai, caused the local government to close down and consider imposing a permanent ban on the “wet markets” that sell live poultry.

Samples from chickens, ducks and pigeons from poultry markets have tested positive for H7N9, but those from migratory birds have not, suggesting that 'the likely source of infection is poultry', said Nancy Cox, at the U.S. Centers for Disease Control and Prevention.

John Oxford, a flu virologist at Queen Mary University of London, told Reuters, This virus seems to have been quietly spreading in chickens without anyone knowing about it.”

Flu experts say it is likely that more cases of human infection with H7N9 flu will emerge in the coming weeks and months, at least until the source of infection has been completely confirmed and effectively controlled.

Anne Kelso, the Melbourne-based director of the WHO Collaborating Centre for Reference and Research on Influenza said that, after Shanghai closed down its live poultry markets in early April, there was an almost immediate decline in new H7N9 cases.

However, experts are reluctant to make any assumptions at this point since the WHO's China representative, Michael O'Leary, issued figures last week showing that only half of the patients analyzed had known contact with poultry.

Read also:

122 Dogs and 410 Pigs Suddenly Die in Chinese Village, Adding to Bird Flu Fears (Video)

20,000 Dead Pigs, Ducks and Swans in China Could Be Linked to New Human Bird Flu

Sources: Reuters, Daily Mail