Human avian influenza cases investigated in Cambodia

Cambodia reported two cases of avian influenza in a father and daughter living in a village in Prey Veng province. An 11-year-old girl died earlier this week.

Cambodia’s first reported case since 2014 has raised concerns that the virus has gained the ability to spread among people and could trigger another pandemic. Four of the girl’s 11 contacts had flu-like symptoms and said they had tested negative for infection with the H5N1 influenza virus.

The 49-year-old father, who tested positive, had not shown any symptoms, according to the Ministry of Health. We’re determining if they got infected (most likely) or if they infected each other.

Experts have noted that there have been hundreds of sporadic cases of H5N1 infection since the virus was first identified, and there is no evidence that it has adapted to humans.

Richard Webby, an avian flu expert at St. Jude Children’s Research Hospital in Memphis and a WHO advisor, said transmission among people was “very rare and common.” In contrast to the source,” he said.

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Avian influenza, or bird flu, is a group of influenza viruses that are primarily adapted to birds. The specific virus in these new cases, called H5N1, was first identified in geese in China in 1996 and in Hong Kong people in 1997.

Since then, nearly 1,000 cases have been reported in 21 countries, mostly due to prolonged direct contact with birds. H5N1 seems not yet adapted to spread efficiently among people.

“At the end of the day, this is the same outbreak streak that started in 1996,” said Dr. Malik Peiris, director of virology at the University of Hong Kong. Southeast Asia. “Really, it never went away.”

H5N1 is commonly carried by waterfowl such as ducks and can transmit the virus to poultry through faeces, saliva, or other secretions.

The current version of the virus is unusually prevalent, causing the largest bird outbreak to date. Europe And in the United States, it’s making an impact 58 million farmed birds in the latter. According to Dr. Webby, it is now thought to be endemic in several countries in Asia and Europe.

The virus has also taken a toll on wild birds, causing mass mortality and particularly affecting carrion-eating animals such as foxes, which may be feeding on infected carcasses.

Reports of human transmission require investigation to confirm that H5N1 is not yet adapted for human-to-human transmission. reported from. An 11-year-old girl died this week, the first bird flu death in Cambodia since 2014.

Experts have been closely monitoring H5N1, especially since the outbreak On a mink farm in Spain In October, it was suggested that the virus could spread efficiently among some mammals.Virus samples isolated from imported mink Genetic mutation This is known to help influenza replicate better in mammals.

No human infections were detected. But a mink-adapted version of the virus may be one step closer to efficient transmission among people.

Scientists would be concerned if the version of H5N1 confirmed in Cambodia turns out to be more similar to that seen in Spain than previous Asian outbreaks, Dr. Peiris said. “It’s important to try to understand exactly what happened in Cambodia,” he added.

In a statement, the WHO said it was “updating its bank of vaccine candidate viruses suitable for production as needed.” WHO is also providing antiviral drugs from available stockpiles.

Genetic analysis can reveal whether H5N1 has acquired mutations that help it spread among people.

“This should give a good hint as to whether the virus has actually gone one step further,” said Dr. Shayan Sharif, an avian immunologist at the University of Guelph, Ontario College of Veterinary Medicine in Canada.

However, it is more difficult to determine how the two families became infected in Cambodia. and the H5N1 samples from the daughter are likely to be nearly identical.

“If both were infected from the same set of chickens, they would be infected with very similar viruses,” he said. It may be more useful to map the viral path.

The virus poses the greatest risk to people who come into direct contact with birds, such as poultry farmers. Security measures on farms and poultry processing plants, including the use of personal protective equipment by workers, help reduce the risk of infection.

Infected flocks are generally culled and farms quarantined to contain local outbreaks. But the virus is now circulating in birds, so experts are beginning to consider whether more extensive measures, such as vaccination of poultry, are needed.

Vaccination has not traditionally been used to control avian influenza in poultry in the United States and Europe. But officials are reconsidering that stance, and trials for an avian flu vaccine are underway.

“I don’t think there’s any need to panic at this point,” Dr. Sharif said. But “when I see the different pieces of the puzzle coming together, I think we need to seriously prepare for emergencies,” he said.