Bird Flu (H7N3) Detected at Fourth Victorian Farm

A test tube labelled "Bird Flu" and eggs in a picture illustration on Jan. 14, 2023. (Dado Ruvic/Illustration/Reuters)

A fourth case of highly pathogenic bird flu has been detected in Victoria, leading to a farm being placed in quarantine.

Tests have identified the H7N3 strain of avian influenza at a poultry farm within the Golden Plains Shire, west of Melbourne.

This comes amid the World Health Organisation advising of the first global death of influenza A (H5N2) in Mexico.

The latest farm in Victoria is within a restricted area where movement controls were already in place due to the bird flu being detected at other properties.

Agriculture Victoria noted consumers do not need to be worried about eggs and poultry products from the supermarket.

“The farm has been placed into quarantine and Agriculture Victoria staff are working closely with industry to reduce the risk of spread,” the Victorian government agency said.

“All poultry will be safely disposed of under veterinary supervision, consistent with national policies and the sites will be cleaned and cleared of the infection.”

Victoria chief veterinary officer Graeme Cooke wasn’t surprised by the detection of bird flu, attributing it to the “ongoing surveillance activities” by staff within restricted areas.

“Avian influenza is a viral disease of birds found globally, many species of wild birds, including waterfowl and seabirds can carry the virus but usually show no signs of disease,” he said.

“We remind bird owners that housing birds, where practical, is an effective method of minimising direct contact with wild birds.”

Dr. Cooke also advised bird owners to follow best biosecurity practices including keeping poultry, sheds, yards, aviaries, and equipment clean and restricting contact between poultry and wild birds.

The government agency noted existing movement controls remain in place in Terang, while restricted and control areas around Meredith have been extended.

Permits are required to move birds, poultry products, feed and equipment on or off properties within restricted and control areas.

On June 3, H7N3 was identified at a Lethbridge farm owned by Farm Pride in south west Victoria. At least 80,000 hens will be euthanised to stop the spread of the virus.

Farm Pride managing director Darren Lurie said the company is implementing strict biosecurity measures and has been following the national response against emergency animal diseases.

“Farm Pride places paramount importance on the quality of our product, food safety, staff welfare, protecting our customers, suppliers and stakeholders, and the health of our hens,” the company said.

This came after the H7N3 highly pathogenic strain of avian influenza was discovered at a property in Meredith, Victoria on May 22.

Then, on May 23, avian influenza virus at a second poultry farm directly connected with the Meredith property via joint management was detected in the Terang region of Victoria. The strain of avian influenza found at the second infected property is H7N9, Agriculture Victoria said on May 26.

What Causes Bird Flu?

Bird flu is caused by a “variety of influenza type A viruses” that usually infect birds, according to Murdoch University Professor of Viral Immunology Cassandra Berry.

The professor explained some of these influenza types are highly pathogenic, known as high pathogenicity avian influenza (HPAI), while others are low.

“The difference lies in the number of basic amino acids at the cleave site of haemagglutinin (HA), a spike protein on the virus surface, which is cleaved by cellular proteases,” she said.

“This cleavage determination then allows the virus to infect cells of different tissues and organs in the body. So if the virus HA is more easily cleaved by proteases, it will be more pathogenic.”

She noted chickens are “highly suspectable” to bird flu and an entire flock can be “decimated” overnight with the highly pathogenic strain of avian influenza.

Ms. Berry noted because influenza viruses can mutate quickly, a low pathogenic avian influenza strain can quickly develop into a highly pathogenic strain.

This means surveillance and biosecurity measures are critical for control of virus outbreaks.

First H5N2 Bird Flu Death Advised by WHO

Meanwhile, the World Health Organisation (WHO) has announced the first human death from A(H5N2), a strain of bird flu not previously found in humans.

A 59-year old man died on April 24 after experiencing fever, breath shortness, nausea, and general discomfort according to the WHO.

The individual had been in bed for three weeks prior to testing positive for the virus and had underlying health conditions.

While the source of exposure to the virus is unknown, the H5N2 virus has been reported in poultry in Mexico, according to the WHO.

“This is the first laboratory-confirmed human case of infection with an influenza A(H5N2) virus reported globally and the first avian H5 virus infection in a person reported in Mexico,” the WHO said. 

US Restricts Poultry From Victoria

Meanwhile, the United States has restricted import of poultry, birds, and unprocessed avian products.

This alert was issued on May 22 until further notice after the avian flu was detected at multiple properties in Victoria.

The U.S. Animal and Plant Health Inspection Service (APHIS) applied the restriction to commercial birds, ratites, avian hatching eggs, poultry, unprocessed avian products and byproducts, and certain fresh poultry products.

“Unprocessed avian products and byproducts originating from or transiting the State of Victoria, Australia will not be permitted to enter the United States. This includes hunter harvested, non-fully finished avian trophies and meat,” the alert states. 

However, processed avian products and byproducts from Victoria can be imported, provided they are accompanied by a permit and a treated as per regulations.

The first Australian case of H5N1 in Victoria was also detected on May 22 in a child who had returned from overseas.