DEFRA: Preliminary Outbreak Assessment - LPAI H5N1 In Scotland

#10,909


Over the past year we've seen a number of LPAI (low path) and HPAI (high path) avian flu outbreaks across Europe  that have included several new strains of avian influenza. In December, we learned of new H5N1, H5N2, and H5N9 subtypes in France, while last summer Germany and the UK were hit by new strains of HPAI H7.

Last week Scotland reported the UK's first outbreak of 2016 (see Fife, Scotland Avian Flu Outbreak Confirmed As LPAI H5N1), and today DEFRA has published their preliminary outbreak assessment (dated, curiously, 5 days ago).

 
The virus has been identified as a European LPAI H5N1 strain, similar to those commonly carried by wild birds. They note it is unrelated to either the Eurasian HPAI H5N1 virus, or to the HPAI H5 viruses circulating in poultry in Southwest France.


The authors find there is a low, but constant risk of poultry infection by H5 and H7 avian viruses in the UK via direct or indirect contact with wild birds, and recommend continued vigilance. 

Low Pathogenic Avian Influenza (H5N1) in the UK (Scotland)
 
14 January 2016 Ref: VITT/1200 LPAI in UK
Disease Report

On January 13th, the UK confirmed an outbreak of Low Pathogenic Avian Influenza (LPAI) subtype H5N1 on a commercial broiler breeder (parent) holding in the region (parish) of Dunfermline, Scotland (OIE, 2016; see map and inset). 


The premises had a flock of approximately 40,000 57 week old housed hens. The birds were housed in 5 sheds and the operation was “all in all out”. Mild clinical signs (egg drop and inappetence) were observed; there was no increase in mortality. Disease control measures were put in place on 8 January, when suspicion was raised after the receipt of the first non-negative laboratory test results. Measures include a 1km restriction zone, culling of all poultry on the infected premises and the destruction of eggs originating in the holding placed at the company hatchery has now been completed. An epidemiological investigation is being undertaken.
 
Situation Assessment

The holding is in a low poultry density area and there are no other commercial premises in the 1km zone, but there are areas where wild birds congregate within a few kilometres. The source of infection is unknown at this stage, and disease investigations continue. In general, LPAI (H5 and H7) viruses are considered to occasionally circulate in European waterfowl. 

National surveillance programmes in Europe have shown H5 seropositive flocks of farmed anseriformes (ducks and geese) and rarely in galliformes (chickens and turkeys) (European Commission, 2005-2014), nevertheless in the last 12 months over twenty outbreaks of various LPAI strains have been reported in domestic poultry in France, Germany, Italy, Netherlands and the UK, which is an indication of high awareness and effective screening in these countries.
 
Genetic sequencing results provided by the UK National Reference Laboratory (NRL) / EU Ref Lab (EURL) confirm that this is a European strain with common ancestry with other European LPAI H5 viruses most probably deriving from similar wild bird progenitor strains. The virus is clearly distinguishable from the Eurasian origin H5N1 viruses causing disease in poultry and occasionally people in close contact with infected poultry in Asia since 2003. It is also unrelated to the HPAI viruses circulating in poultry in Southwest France.

An interrogation of TRACES, the EU trade notification system, indicate there has been no recent trade to other Member States or Third countries of live poultry, hatching eggs or day old chicks from the affected premises or the restriction zone.
 
Conclusions
 
We consider that there is a constant low risk of incursion of any notifiable avian disease into the poultry in the UK from direct or indirect contact with wild birds. Prompt reporting of disease by farmers and vets in the UK, rapid diagnosis and swift disease control measures, often in advance of final strain identification, as in this case, enable rapid eradication from the UK poultry flock. The risk to public health and food safety is negligible.
 
For exports to non-EU countries the UK has taken immediate action to ensure that, in those cases where an importing country requires national freedom from Avian Influenza (i.e. that there be no reported cases of AI within the UK), the relevant Export Health Certificates have been suspended. In most cases the principle of regionalisation has been applied to enable trade to continue from outside the restricted area.
 
This disease event emphasises the importance of maintaining vigilance and appropriate biosecurity measures at all times throughout the year on poultry premises. Livestock keepers are reminded of the requirement to report all suspect notifiable diseases. 

We will continue to report on the situation if there are any significant changes.
 

Authors
Dr Helen Roberts
Professor Ian Brown