Thursday, January 06, 2022

UKHSA Statement On Human H5 Infection In England

Credit DEFRA 


Although it is causing quite a stir on twitter, the announcement (below) of a human infection with a novel H5 flu virus isn't all that unexpected, given previous transmissions reported over the past year in Russia and Nigeria.  

Despite carrying the same name, the H5N1 virus currently spreading across Europe is not of the same lineage as the more dangerous Asian H5N1 virus which has caused hundreds of human infections over the past 20 years, and carries a 50% CFR (Case Fatality Rate). 

First the statement from the UKHSA, then I'll return with a postscript.

Human case of avian flu detected in UK

The UK Health Security Agency has confirmed a case of avian influenza in a person in the South West of England.

From:UK Health Security Agency Published 6 January 2022

Bird-to-human transmission of avian flu is very rare and has previously only occurred a small number of times in the UK.

The person acquired the infection from very close, regular contact with a large number of infected birds, which they kept in and around their home over a prolonged period of time.

All contacts of the individual, including those who visited the premises, have been traced and there is no evidence of onward spread of the infection to anyone else. The individual is currently well and self-isolating.

The risk to the wider public from avian flu continues to be very low. However, people should not touch sick or dead birds.

Avian flu, also known as bird flu, is a type of influenza that spreads among birds. The UK has recently seen a large number of outbreaks and incidents of avian influenza in birds across the country of the H5N1 strain and Animal and Plant Health Agency (APHA) and the UK’s Chief Veterinary Officer have issued alerts to bird owners.

Some strains of bird flu can pass from birds to people, but this is extremely rare. It usually requires close contact with an infected bird, so the risk to humans is generally considered very low. Human-to-human transmission of bird flu is very rare.

The case was detected after APHA identified an outbreak of outbreak of the H5N1 strain of avian flu in their flock of birds. Their infection was identified through the routine monitoring which is conducted on anyone who has close contact with infected birds. The infected birds have all been culled.

In line with the highly precautionary approach that the UK Health Security Agency (UKHSA) takes to identifying and stopping the transmission of avian flu, UKHSA swabbed this person and detected low levels of flu. Further laboratory analysis revealed that the virus was the ‘H5’ type, found in birds.

At this point it has not been possible to confirm that this is a H5N1 infection (the strain that is currently circulating in birds in the UK). Based on the available evidence, the World Health Organization (WHO) has been notified.

This is the first human case of this strain in the UK, although there have been cases elsewhere globally.

Professor Isabel Oliver, Chief Scientific Officer at UKHSA, said:

While the risk of avian flu to the general public is very low, we know that some strains do have the potential to spread to humans and that’s why we have robust systems in place to detect these early and take action.

Currently there is no evidence that this strain detected in the UK can spread from person to person, but we know that viruses evolve all the time and we continue to monitor the situation closely. We have followed up all of this individual’s contacts and have not identified any onward spread.

It remains critical that people do not touch sick or dead birds, and that they follow the DEFRA advice about reporting.

The UK’s Chief Veterinary Officer, Christine Middlemiss, said:

While avian influenza is highly contagious in birds, this is a very rare event and is very specific to the circumstances on this premises.

We took swift action to limit the spread of the disease at the site in question, all infected birds have been humanely culled, and cleansing and disinfection of the premises is underway. This is a reminder that stringent cleanliness when keeping animals is important.

We are seeing a growing number of cases in birds on both commercial farms and in backyard flocks across the country. Implementing scrupulous biosecurity measures will help keep your birds safe.

UKHSA follows up all individuals who have been in contact with a confirmed case of avian influenza. For those with the highest risk exposures, we contact them daily to see if they have developed symptoms so that we can take appropriate action.

People are also offered anti-viral treatment after exposure to infected birds. This is to stop the virus reproducing in their body if they have picked it up and should prevent them from becoming unwell. It also helps reduce the risk of passing the infection on to others.

We also swab people even if they don’t have symptoms, to help our surveillance programmes and make sure we identify anyone infected so that we can take action to control any risk of transmission.

UK Health Security Agency press office

The UK, and much of Europe, are in the midst of their second consecutive year of a record setting outbreaks of avian H5Nx - mostly H5N1 this year -  affecting both wild and captive birds.  

Thought to be only a threat to wild birds and poultry until as recently as the spring of last year, H5 clade viruses are now known to be capable of infecting humans (see CDC Adds Zoonotic Avian A/H5N8 To IRAT List), although all known cases have been either mild or asymptomatic.

Since 2016 we've seen increasing avian mortality and increased host range in HPAI H5Nx viruses circulating in Europe, including serious infection of several mammalian species (see CDC EID Journal: Encephalitis and Death in Wild Mammals at An Animal Rehab Center From HPAI H5N8 - UK).

Not quite two weeks ago, in ECDC/EFSA Raise Zoonotic Risk Potential Of Avian H5Nx, we looked at growing concerns over the continued evolution of these H5 clade viruses, and their potential to jump species to humans.

While these European H5 viruses haven't shown the same pathogenicity in humans as their Asia cousins, they do bear watching.  For more on the spread and evolution of these viruses, you may wish to revisit:

Science: Emerging H5N8 Avian Influenza Viruses

V. Evolution: Genomic Evolution, Transmission Dynamics, and Pathogenicity of Avian H5N8 Viruses Emerging in China, 2020

DEFRA: Highly Pathogenic Avian Influenza (HPAI) in the UK, and Europe