Human Case of Bird Flu in Australia Was Sent to the WHO for Detection

Influenza A samples were sent to the WHO for ‘further characterisation’ as part of a batch.

A person holds a test tube labelled "Bird Flu" in a picture illustration on Jan. 14, 2023. Dado Ruvic/Reuters

Australia’s first bird flu H5N1 infection was sent to the World Health Organisation (WHO) for further characterisation before it was formally identified.

The revelation comes after an Avian Influenza A (H5N1) case was identified in a two-and-a-half-year-old child who had travelled to India.

A nasopharyngeal swab and endotracheal aspirate that was taken on March 6 and 7 tested positive for influenza A at a referral hospital in Melbourne, Victoria, and was then sent to the WHO.

“The samples were sent to the WHO CC for further characterisation on 3 April as part of a batch, as there was insufficient knowledge from the referring practitioners at the hospital to connect the case to the H5N1 virus,” the WHO said in a statement on June 7.

Further, the WHO explained a virus genetic sequence obtained from the samples confirmed the subtype A(H5N1) and indicated that the haemagglutinin (HA) gene belonged to clade 2.3.2.1a.

This variant circulates in South-East Asia and has been detected in previous human infections and poultry.

Monitoring and Investigation Team

The statement also provided some insight into the Australian government’s “monitoring and investigation team” (MIT) within the Australian federal health department.

According to the WHO, this monitoring team is meeting regularly, the frequency of which will be “reassessed as required.”

“Currently the MIT is meeting weekly, to assess any ongoing risk of the overall highly pathogenic avian influenza situation in Australia associated with the confirmed case of H5N1 in Victoria and the current international HPAI outbreaks,” the statement said.

A National Incident Centre within the department has been activated to “coordinate the response” to 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.

Ms. Berry said 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.”

 Australia’s First H1N1 Bird Flu Case

The Victorian Department of Health first advised the public of a human case of avian influenza in Australia in late May.

The department advised at the time the case was found in a child, who acquired the infection in India and was unwell in March 2024.

“The avian influenza virus was detected through further testing of positive influenza samples that takes place to detect novel or concerning flu virus strains, as part of Victoria’s enhanced surveillance system,” the department said.

The WHO said while the source of exposure to the virus in this case is currently unknown, the “exposure likely occurred in India.”

Chief Health Officer Dr. Clare Looker, who signed off on the Victorian advisory, said the child experienced a severe infection but is no longer unwell and has made a full recovery.

The advisory said transmission to humans is “very rare” and the “chance of additional human cases was ”very low“ because ”avian influenza does not easily spread between people.

At the time, Victorian health authorities recommended the uptake of the seasonal flu vaccine to reduce the risk of the emergence of new mutated viruses.

“The seasonal flu vaccine doesn’t protect against avian influenza. However, it can help prevent the mixing of highly pathogenic avian influenza with seasonal influenza, which can lead to new mutated viruses that could spread rapidly,” the Victorian government said.

“This highlights the importance of seasonal influenza vaccination, particularly for poultry workers and those travelling to areas with outbreaks, to reduce the risk of new human pandemic viruses emerging.”

In addition, Victoria Health advised the jab can be taken by everyone aged older than six months to prevent influenza and its complications.

Professor Paul Kelly, head of the interim Australian Centre for Disease Control, also issued a statement on the human case of H5N1 detected in Australia on May 23.

“This is the first human case ever recorded in Australia. Bird flu does not easily infect humans and there is no ongoing public health risk from this case,” Mr. Kelly said.

“The CDC is liaising closely with the Australian Government Department of Agriculture, Fisheries and Forestry, which is the lead agency responsible for monitoring the threat posed to Australia by the global spread of A(H5N1) in animal and bird populations.”

Meanwhile, Australian Health Minister Mark Butler met with WHO Director-General Tedros Adhanom Ghebreyesus in Geneva to discuss the pandemic agreement and negotiations on International Health Regulations (IHR) amendments.

“Met with Australia’s Health Minister Mark Butler MP to discuss their work to end HIV, the Pandemic Accord, and the International Health Regulations Amendments negotiations, and the WHO Investment Round,” Mr. Ghebreyesus wrote on X on May 31.