Belgium: Non-Reportable LPAI H3N1 Continues To Spread

Highlights

•  Media now reports 26 outbreaks of LPAI H3N1

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Yesterday, in Belgium: Non-Reportable LPAI H3N1 In Poultry, we looked at dthe recent outbreak of a Low Path avian H3N1 virus - which is not considered a reportable disease by the OIE - which has caused significant mortality among infected chickens.

Today, the news is that the virus continues to spread, and has now been reported on at least 26 farms in and around West Flanders. This (translated) report comes from https://www.nieuweoogst.nu.

Belgium Bird flu is spreading rapidly around

Poultry Mariska Bloemberg-van der Hulst 07 May 2019

There are now 26 Belgian poultry infected with bird flu. Although the case of the low pathogenic variant H3N1, the disease is spreading rapidly around with very high mortality rates among a laying animals.

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Since H5 and H7 are the only LPAI viruses considered reportable by the OIE, this outbreak would have likely gone unnoticed were it not for its unusually high mortality rate (said to be as high as 60%).

LPAI H3 infections are not uncommon in birds - particularly ducks - but occasionally turn up in poultry, although H3N2 and H3N8 appear to be more common than H3N1. 

• A reassorted LPAI H3N1 appeared in Pakistan in 2010 (see Isolation, identification, and phylogenetic analysis of reassortant low-pathogenic avian influenza virus H3N1 from Pakistan), but produced little or no mortality. 

• Between 2009 and 2011 LPAI H3N2 and H3N8 avian viruses were isolated from live markets in China (see Phylogenetic analysis and pathogenicity of H3 subtype avian influenza viruses isolated from live poultry markets in China), but once again produced little or no overt signs of illness in chickens.  

All of which makes Belgium's LPAI H3N1 virus a bit of an outlier, and a challenge for local authorities who are trying to contain it without benefit of a clear protocol.

Of greater concern is what genetic changes may have occurred in this LPAI H3N1 virus to increase its impact on chickens, and whether those changes alter its threat profile or impact its host range. 

As the ecology and diversity of avian flu viruses becomes more complex, we may find we need to adopt new standards and measures in order to deal with them effectively.

Stay tuned.