Australia, Philippines and Russia report return of avian flu in poultry

Recent mortalities and reduced production in poultry have been linked to highly pathogenic avian influenza (HPAI). Countries confirming the latest outbreaks are on different continents, and three virus families are involved. Meanwhile, new research highlights the need to protect domestic poultry from wild birds, which represent the most likely source of infection.

(mashi_naz | Bigstock)
(mashi_naz | Bigstock)

Recent mortalities and reduced production in poultry have been linked to highly pathogenic avian influenza (HPAI). Countries confirming the latest outbreaks are on different continents, and three virus families are involved. Meanwhile, new research highlights the need to protect domestic poultry from wild birds, which represent the most likely source of infection.

Avian influenza returns to Australia

After an absence from Australia of more than six years, HPAI has been detected at a commercial farm in the state of Victoria.

At the end of July, all the poultry in one house at the free-range farm in Lethbridge began to show symptoms of the disease, according to the official report lodged with the World Organisation for Animal Health OIE). Around 1,670 of the birds died. There were no clinical signs in birds housed in a second barn.

Samples taken from the farm revealed the presence of the H7N7 virus variant, which was last detected in Australia in February of 2014. The source of this latest infection is uncertain, but it may be linked to contact with wild birds.

When the outbreak started, the farm was quarantined, and a protection zone was set up in a five-kilometer radius of the affected property, reported News.com.

According to the Department of Agriculture, Water, and the Environment, the affected premises was an egg farm. It stresses that while this virus type can cause high mortality among poultry, it is not a risk to the general public. Poultry meat and eggs are still safe to eat.

In response to the outbreak, Agriculture Victoria began working with the industry to undertake appropriate response activities. This followed approval of a response plan by the National Management Group, which comprises government bodies and industry representatives.

HPAI returns to Russia’s Ural mountain region

In the last days of July, high mortality was reported among poultry at non-commercial holdings in the Urals federal district of Russia.

Affected were a village flock and a backyard in the same district of Uvelsky in the Chelyabinsk oblast, reported the agriculture ministry to the OIE.

All the birds — chickens, ducks, and geese — of the backyard flock died, as did the majority of those in the village. Culling of the rest of the rest was underway at the time of reporting.

According to the OIE report, source of the infection is thought to be contact with wild birds. A duck found dead in the area has tested positive for the H5N8 HPAI virus. The infection was last detected in this region in November of 2005.

Philippines’ outbreak linked to wild birds

Following reports by local media, the Department of Agriculture in the Philippines confirmed to the OIE an outbreak of HPAI linked to the H5N6 virus subtype.

At a commercial egg farm in the town of San Luis in Pampanga, hens in two separate poultry houses began to show signs of disease during the first week of July. Egg production dropped, and the birds had discolored combs, nasal discharge, and many died within 24 hours.

Of the 39,161 birds at the affected premises, 465 died, and the rest were culled by mid-July.

The last confirmed outbreak in the area was in March of 2018. Wild birds are thought to have transmitted the infection to the farm. Waterfowl were present in adjacent rice fields.

An inter-agency National Avian Influenza Task Force has approved recommendations of the Department of Agriculture to manage the emerging HPAI outbreak, reports Philippine News Agency.

Measures include monitoring of the H5N6 HPAI virus by local governments, as well as an information campaign to publicize the safety of poultry meat and eggs. Disease control measures are focused on the area around San Luis, where the outbreak occurred.

In 2017, the province of Pampanga on the island of Luzon was the epicenter of the HPAI outbreak in the Philippines.

As well as these latest developments, OIE records in its latest update on the avian flu situation in Asia on-going outbreaks of HPAI in poultry in Afghanistan, China, India, North Korea, Taiwan, and Vietnam. In Afghanistan, China, and India, avian flu viruses are known to be present in other bird species.

Study shows avian flu viruses swap genes

Although caused by different virus variants, source of infection in all these latest outbreaks of HPAI in poultry — in Australia, the Philippines, and Russia — were thought to be through contact with wild birds.

To underscore the threat of non-poultry species in the transmission of the virus to domestic birds, there is new evidence of the threat from a newly published study.

Results of the work led a multinational group of researchers to conclude that commercial poultry need to be protected from wild species during the migration season to prevent infection.

As a member of the Global Consortium for H5N8 and Related Influenza Viruses, the Roslin Institute in Edinburgh, United Kingdom, reports the focus on the genetic composition of one particular HPAI virus.

Studying the virus circulating in 2016-17, the findings help to explain how an HPAI virus becomes established in wild bird populations.

“Bird flu viruses can readily exchange genetic material with other influenza viruses,” said Dr. Sam Lycett. “This, in combination with repeated transmission of viruses between domestic and wild birds, means that a viral strain can emerge and persist in wild bird populations, which carries a high risk of disease for poultry.”

From the genetic sequencing data, it appears that the virus can easily exchange genetic material with other viruses that are less harmful. Furthermore, the scientists believe this exchange occurs at times and locations linked to the migratory patterns of wild birds — for example, when their routes intersect, or though farmed ducks in China or central Europe.

View our continuing coverage of the global avian influenza situation.

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