H5N8 – A long way from home
# 9320
The recent, and quite unexpected arrival of avian H5N8 avian influenza at a poultry farm in central Europe (see Germany Reports H5N8 Outbreak in Turkeys) – less than a year after it first emerged on the Korean peninsula - has set off multiple alarm bells across Europe and Asia.
This Highly pathogenic influenza virus infected dozens of poultry operations last spring in South Korea, forcing the culling of 13 million birds.
How it managed to travel – undetected – 8,000 miles to Northern Germany remains a mystery, although migratory birds are considered a plausible suspect (see Bird Flu Spread: The Flyway Or The Highway?)..
Unlike its notorious H5N1 cousin, H5N8 is not known to infect humans, although South Korea did report Dogs With H5N8 Antibodies last spring. As the virus spreads, however, it continues to evolve (see EID Journal: Describing 3 Distinct H5N8 Reassortants In Korea), giving rise to concerns that it could someday pose a greater human health threat.
For now, H5N8 is viewed as primarily a threat to poultry.
The ECDC has produced a Rapid Risk Assessment (excerpts below), where we learn more about the lineage of this German H5N8 virus - that it is indeed, closely related to the Korean strain – identifying it as belonging to H5 HA (provisional) clade 2.3.4.6.
This is the same H5 clade that has been seen in H5N1, H5N6, and H5N8 across much of Eastern Asia over the past year. The graphic below, showing its geographic spread, comes from the recent FAO-EMPRES Report On The Emergence And Threat Of H5N6.
While their human health implications are far from clear, over the past year we’ve seen a steep rise in the number of new H5 reassortants coming out of China (see China: H5 AI Rising). In just under 10 months we’ve seen H5N8, H5N6, and H5N3 emerge, along with an ever expanding array of H5N1 and H5N2 clades and variants.
Yesterday, in EID Journal: Subclinical HPAI In Vaccinated Poultry – China, we looked at one of the factors that may be driving this expansion of the H5 lineage.
Added to this rogues gallery of avian flu viruses, we also have a growing number of variants of the H7N9 virus, and upstarts like H10N8 to contend with. With winter on its way, Chinese authorities are once again on guard, fully expecting a new wave of human H7N9 infections over the next few months.
After a decade with basically only H5N1 and some lesser H7 viruses to worry about, this expanded roster of avian flu viruses re-emphasizes the need for better poultry farm biosecurity and surveillance. Below you’ll find excerpts from the ECDC’s Rapid Risk Assessment. Click the link to download the entire document.
RAPID RISK ASSESSMENT
Outbreak of highly pathogenic avian influenza A(H5N8) in Germany
13 November 2014
Main conclusions and recommendations
On 6 November 2014, German authorities reported an outbreak of highly pathogenic avian influenza virus A(H5N8) at a turkey holding. Culling of the turkeys at the affected holding has started, protection and surveillance zones have been established, and investigations initiated to establish how the birds became infected.
This virus has been detected among wild birds in south-east Asia where it has also caused several outbreaks on commercial poultry farms in South Korea and China. However, this is the first time it has been detected in Europe. It remains unclear how this virus was introduced into a turkey flock at a German holding.
The public health threat from this event is considered very low. To date, no human infections with this virus have ever been reported world-wide and the risk for zoonotic transmission to the general public in the EU/EEA countries is considered to be extremely low. The ability of this highly pathogenic avian influenza virus to subclinically infect wild birds increases the risk of geographical spread and subsequent outbreaks, as observed in South Korea. The ongoing monitoring and testing of wild birds and domestic poultry in the EU therefore plays an important role in the possible detection of further virus occurrences.
In order to prevent virus spread the Directive 2005/94/EC requires that Member States have contingency plans detailing measures for the killing and safe disposal of infected poultry, feed and contaminated equipment as well as the procedures and methods for cleaning and disinfection. Persons at risk are mainly people in direct contact/handling diseased turkeys and other poultry, or their carcasses (e.g. farmers, veterinarians and those labourers involved in the culling.) It is further required that contingency plans for the control of avian influenza in poultry and birds be developed in collaboration with public health authorities to foresee that persons at risk are sufficiently protected from infection.Poultry workers exposed at the affected holding should be monitored for ten days in order to document possible related symptoms. Local health authorities may consider actively monitoring these groups.
<SNIP>
ECDC threat assessment for the EUThe public health threat from this event is considered very low. To date, no human infections with this virus have ever been reported world-wide and the risk for zoonotic transmission to the general public in the EU/EEA countries is considered to be extremely low.
In order to prevent virus spread the Directive 2005/94/EC [10] requires that Member States have contingency plans detailing measures for the killing and safe disposal of infected poultry, feed and contaminated equipment as well as the procedures and methods for cleaning and disinfection. Persons at risk are mainly people in direct contact/handling diseased turkeys and other poultry, or their carcasses (e.g. farmers, veterinarians and those labourers involved in the culling.) It is further required that contingency plans for the control of avian influenza in poultry and birds must be developed in collaboration with the public health authorities to foresee that persons at risk are sufficiently protected from infection.
Persons in direct contact with infected poultry before or during culling and disposal should inform authorities and healthcare providers about the exposure if they develop influenza-like illness or other symptoms, such as fever or conjunctivitis.
To date, there is no epidemiological evidence that avian influenza can be transmitted to humans through the consumption of cooked food, notably poultry meat and eggs.
<SNIP>Conclusions
There is wide diversity in the re-assorted avian influenza viruses circulating in wild bird populations across southeast sia. The ability of this highly pathogenic avian influenza virus to sub-clinically infect wild birds increases the risk of geographical spread and subsequent outbreaks, as observed in South Korea. The ongoing monitoring and testing of wild birds and domestic poultry in the EU therefore plays an important role in the possible detection of further virus occurrences.
It remains unclear how this virus was introduced into a turkey flock at a German holding. The ongoing investigations into the probable transmission chain may provide information that could be important for the prevention of further outbreaks in the EU.
Poultry workers exposed at the affected holding should be monitored for ten days, in order to document possible related symptoms. Local health authorities may consider actively monitoring these groups.
