Bird flu found in Victorian egg farm, returned traveller

Two separate instances of avian influenza (bird flu) were reported in Victoria yesterday — one in a child who returned from overseas earlier this year, and the other in the form of an outbreak on an egg farm.

Avian influenza is caused by an influenza type A virus that typically infects birds. Some subtypes are more likely to cause disease and death in poultry; these are known as highly pathogenic avian influenza (HPAI) viruses. Most humans are not at risk of infection, unless they have contact with infected birds or animals, or their secretions, while in affected areas of the world.

Significant outbreaks of HPAI viruses have recently been reported in poultry and non-poultry birds and mammals overseas, with the United States currently experiencing outbreaks of HPAI (H5N1) in dairy cows and one recent human case in a dairy worker; this has caused some to fear that a global outbreak may be imminent. It was therefore somewhat concerning when Agriculture Victoria yesterday announced it was investigating a number of poultry deaths at an egg farm near the town of Meredith in the state’s west.

After preliminary tests confirmed the presence of the avian influenza virus, samples were delivered to the CSIRO Australian Centre for Disease Preparedness in nearby Geelong to determine the type and nature of the disease. The strain of the virus was determined H7N3, which is the most commonly occurring variant in Australia and thankfully not related to H5N1; Victorian Chief Veterinary Officer Dr Graeme Cooke suggested it may have spilled over from Australia’s wild bird population, as it does from time to time. The affected farm has since been placed into quarantine, and hundreds and thousands of its chickens euthanased — with Victorian poultry keepers and bird owners encouraged to follow best biosecurity practices and to report any unexplained bird deaths to the Emergency Animal Disease Hotline (1800 675 888).

Shortly after this news was reported, the Victorian Department of Health announced it had detected an H5N1 infection in a child who acquired the infection while in India and became unwell in March. This is the first confirmed human case of HPAI in Australia, and the first time the H5N1 strain has been detected in a person or animal in Australia. The virus was detected through further testing of positive influenza samples that takes place to detect novel or concerning flu virus strains.

While the Victorian case is HPAI (H5N1), it is understood not to be the same as the strains that have caused outbreaks in the US. The child did experience a severe infection but is no longer unwell and has made a full recovery. There is also no evidence that the H5N1 strains of avian influenza circulating globally can be spread easily from human to human, with contact tracing indicating no trace of onwards spread in this case.

The Victorian Department of Health is recommending that people travelling to areas affected by avian influenza avoid contact with wild or domesticated birds, including at poultry farms and wet markets; wash their hands after handling uncooked poultry products; and ensure that poultry products are cooked thoroughly before eating. Travellers and poultry workers are also recommended to receive the annual seasonal influenza vaccine, which can help prevent the mixing of HPAI with seasonal influenza to form new mutated viruses. Finally, health professionals are asked to ensure diagnostic samples are taken for influenza PCR and sent for further typing in returned travellers presenting with influenza-like illnesses who have epidemiological risk factors for avian influenza.

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