Guidance

Avian Influenza A(H5N8): risk assessment

Updated 12 March 2021

Background

Avian influenza A(H5N8) is an emergent, highly pathogenic avian influenza (HPAI) virus that affects birds. It was first reported in January 2014 and in the same year, HPAIs of subtype H5 caused outbreaks in poultry in Europe, North America and East Asia. In November 2014 an outbreak of HPAI A(H5N8) occurred on a duck farm in East Yorkshire. There were no human infections related to the 2014 HPAI A(H5N8) outbreak in East Yorkshire.

In 2015, 2 HPAI strains, HPAI A(H5N2) and HPAI A(H5N8), were identified in both wild birds and poultry in the US and Canada. These 2 strains caused poultry outbreaks across 17 states of the US, affecting more than 11 million birds. Despite widespread outbreaks in poultry and exposure of humans, follow-up studies of contacts did not identify illness in humans.

During winter 2016 to 2017, a significant number of European countries, as well as Russia, reported the identification of HPAI A(H5N8) in a variety of wild bird species, including migratory birds. These included:

• Croatia
• Austria
• Poland
• Denmark
• France
• The Netherlands
• Sweden
• Romania and
• Republic of Ireland ^{[footnote 1]}

This was in addition to identification of this virus in the United Kingdom.

At the beginning of October 2017, 2,781 outbreaks of H5N8 influenza in poultry, wild birds, and captive birds had been reported by the European Union Reference Laboratory for avian influenza. A review of these outbreaks in 2016 to 2017, included information on 524 exposed persons – no human infections were identified by PCR testing ^{[footnote 1]}.

The viruses detected in Europe in 2016 to 2017 and those detected in North America in 2014 to 2015 were all closely related but distinguishable.

In November 2020, a poultry outbreak of HPAI A(H5N8) was confirmed in Cheshire, England. In the same month, the Department for Environment, Food and Rural Affairs (DEFRA) raised the risk level for avian influenza incursion in wild birds in GB from ‘medium’ to ‘high’. The risk level for the disease being introduced to poultry premises in GB was also raised to ‘medium’.

As of 2 March 2021, 20 HPAI H5N8 outbreaks have been reported among captive bird and poultry premises across the UK:

• 16 in England
• 1 in Wales
• 1 in Scotland
• 2 in Northern Ireland

There have also been approximately 300 findings of avian influenza in wild birds in 69 locations across Great Britain, including Avian Influenza A(H5N8) among other subtypes. Public health follow-up of these detections has not identified any human infection to date.

Samples of the viruses detected in the 2014 East Yorkshire outbreak were analysed for mutations that would make them more pathogenic for humans – they were found to be predominantly avian-adapted, with a low affinity for humans ^{[footnote 2]}.

The Animal and Plant Health Agency (APHA) has undertaken the same analysis for virus detected in the HPAI A(H5N8) outbreak among poultry in Cheshire, reported in November 2020. APHA also concluded that these have a similar and low affinity for humans.

In February 2021, the World Health Organization (WHO) reported 7 human cases of Avian Influenza A(H5N8) from the Russian Federation. These cases were detected by PCR testing following an outbreak of Avian Influenza A(H5N8) at a large poultry farm in Russia. The human cases were all asymptomatic – no evidence was reported of spread from these individuals to other people. This is the first time human infection has been reported, despite health surveillance of exposed persons previously being undertaken in many countries for confirmed Influenza A(H5N8) infections in avian species.

Risk to the general public

Following human cases of Avian Influenza A(H5N8) reported to WHO for the first time in February 2021 from Russia, the public health risk has been reviewed.

The public health risk of HPAI A(H5N8) infection within the UK is low.

The public heath risk of HPAI A(H5N8) infection to UK residents who are travelling to countries currently affected is low.

Travellers to affected countries should follow the advice provided below around reducing exposure to poultry and wild birds. The National Travel Health Network and Centre (NaTHNaC) website provides further travel advice.

Risk to people occupationally exposed

There have been 7 cases of human infection amongst poultry workers at a farm with a known Avian Influenza A(H5N8) outbreak in Russia.

Use of appropriate personal protective equipment (PPE) continues to be recommended for all those exposed during incidents, as part of interim recommendations specific to Avian Influenza A (H5N8) cases.

Those involved in the culling, clean-up and disposal of infected birds during previously reported Avian Influenza A(H5N8) outbreaks should also be provided with antiviral prophylaxis – while working on the infected premises and 10 days afterwards.

The Health and Safety Executive (HSE) provide guidance on the appropriate PPE for people who are occupationally exposed.

The risk to persons occupationally exposed to HPAI A(H5N8) is slightly higher than for the general public but is considered to be low when appropriate interventions are implemented, such as use of full PPE and antiviral prophylaxis.

It is normal practice to monitor for 10 days since last exposure people who have been potentially exposed in affected premises or having direct contact with diseased birds or poultry and their carcasses, dependent on the local risk assessment, in order to identify any relevant symptoms.

Advice for travellers and the public

No specific restrictions to travel are advised in relation to avian influenza. However, to help reduce the risk of exposure and infection, travellers to countries affected by an avian influenza outbreak should be aware of the following general travel advice:

• do not pick up or touch sick, dying or dead poultry or wild birds
• avoid contact with surfaces contaminated with bird faeces
• avoid untreated bird feathers (such as those found in the environment) and other bird waste
• do not eat or handle undercooked or raw poultry, egg or duck dishes
• do not attempt to bring any poultry products back to the UK
• maintain good personal hygiene with regular hand washing with soap and use of alcohol-based hand rubs

Travellers should consider separate advice related to COVID-19 and travel.

In Great Britain, the APHA has advised that the majority of dead wild birds would not have Avian Influenza infection, based on surveillance activities.

However, members of the public should follow routine precautions to prevent any other risks to their health, by following the above advice about contact with avian species, bird feathers, and bird waste.

The UK Health Security Agency (UKHSA)’s actions

UKHSA will manage incidents of Avian influenza A(H5N8) with the strict approach which requires antiviral prophylaxis for all those exposed to infectious materials, in addition to use of personal protective equipment (PPE). All those working on premises infected with H5N8 are advised to wear PPE in accordance with HSE guidance. Health advice will also be given to exposed persons depending on the nature of their exposures.

UKHSA will continue to monitor international avian influenza A(H5N8) activity and work with colleagues in the APHA and DEFRA to respond to any further outbreaks.

1. Adlhoch C, Dabrera G, Penttinen P, Pebody R; Country Experts. Protective Measures for Humans against Avian Influenza A(H5N8) Outbreaks in 22 European Union/European Economic Area Countries and Israel, 2016 to 2017. Emerg Infect Dis. 2018 Oct;24(10):1-8. doi: 10.3201/eid2410.180269. Epub 2018 Oct 17. PMID: 29989531; PMCID: PMC6154149. ↩ ↩²

2. Hanna A, Banks J, Marston DA, Ellis RJ, Brookes SM, Brown IH. Genetic Characterization of Highly Pathogenic Avian Influenza (H5N8) Virus from Domestic Ducks, England, November 2014. Emerg Infect Dis. 2015 May;21(5):879-82. doi: 10.3201/eid2105.141954. PMID: 25898126; PMCID: PMC4412239. ↩