‘Epicentre beyond Asia’: Deadly bird flu outbreaks ‘migrated’ to Europe and Africa, finds study

A study conducted by an international team of scientists led by the University of Hong Kong found that the epicentre of the deadly bird flu outbreaks moved to Europe and Africa from Asia. The findings of the research published in the journal, Nature on Wednesday (Oct 18) also suggest that the strain currently circulating worldwide has become increasingly infectious among wild birds.

How was the study conducted?

The international team of researchers analysed the outbreaks of the H5N1 which has been classified as a highly pathogenic avian influenza (HPAI) virus given the high death toll in poultry. It was said to have been first detected in birds in China back in 1996.

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Scientists studied the outbreaks between 2005 and 2022 and used the data on confirmed cases from the Food and Agriculture Organization (FAO) and the World Organisation for Animal Health (WOAH).

They have attributed the current outbreak to a highly infectious variant of H5N1 which is becoming increasingly infectious to wild birds.

It also caused Europe’s worst bird flu outbreak, before spreading globally. This strain has reportedly reached every continent except Oceania and Antarctica.

What was found?

The bird flu viruses which typically emerged from Asia for 25 years had not undergone any major change but their spread among wild birds indicates that the outbreaks are shifting, said the study.

The current strain first emerged in Europe in 2020.Around that time researchers also noted how the rate of spread among wild birds was three times faster than that in farmed poultry due to the mutations which allowed the virus to adapt to diverse species.

The spread of bird flu within the poultry industry is determined by human activityand the trading of birds. However, for wild birds, it is their migratory routes that indicate where the disease will spread and with flyways along the east Atlantic and Pacific, the virus was able to spread to areas that had never been exposed to it before.

“These results highlight a shift in the HPAI H5 epicentre beyond Asia,” researchers wrote in the paper. The study also noted how outbreaks are typically seasonal and synchronise with bird migration in the Northern Hemisphere.

However, since November 2021, they have become persistent which led to the killing of millions of birds across five continents in 2022.

But despite the number of outbreaks, only 0.2 per cent of cases were sequenced, the researchers noted, urging the countries to ramp up surveillance to understand how the virus is changing.

Need for better data collection

To study the changes in the virus’behaviour, researchers also analysed more than 10,000 viral genomes and found that around mid-2020, a new H5N1 strain evolved from an earlier variety, called H5N8.

This new variant first emerged in poultry in Egypt between 2016 and 2017 and is said to be the cause of global flare-ups throughout 2020 and 2021.

“Once it’s adapted to wild birds, we have no mechanism to control the virus. And I think that’s the biggest impact that has changed now,” says co-author Vijaykrishna Dhanasekaran from the University of Hong Kong.

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