Wednesday, December 28, 2016

South Korea Detects H7N7 & H7N2 In Wild Birds


Under the heading of `If you look, you'll probably find it', South Korean officials have announced that their enhanced wild bird surveillance for HPAI H5N6 and HPAI H5N8 has turned up low path H7 viruses including H7N7 and H7N2.

First this report from KBS World News:

Other Strains of AI Detected in Wild Birds in S. Korea
Write : 2016-12-28 08:56:37 Update : 2016-12-28 09:23:59
As the highly pathogenic H5N6 bird flu is sweeping South Korea, other strains of the disease have also been detected in wild birds.

The Ministry of Agriculture, Food and Rural Affairs said on Tuesday that feces of wild birds in Sacheon, South Gyeongsang Province, were confirmed to have carried the H7N7 strain of avian influenza(AI).

The confirmation comes after another H7 strain of bird flu, H7N2, was detected in wild bird feces in Buan County, North Jeolla Province, on December 17th.

The ministry said both H7 strains were not highly contagious and would not cause a serious problem. 

However, it is known to be looking into the possibility that the highly pathogenic H7N9 strain will spread in the country. H7N9 infected 808 people in Hong Kong and Canada in recent years, killing 324 people.

A formal announcement has not yet appeared on the South Korean MAFRA website.

There are two broad categories of avian influenza; LPAI (Low Pathogenic Avian Influenza) and HPAI (Highly Pathogenic Avian Influenza).

  • LPAI viruses are quite common in wild birds, cause little illness, and only rarely death.  They are not considered to be a serious health to public health. The concern is (particularly with H5 & H7 strains) that LPAI viruses have the potential to mutate into HPAI strains.
  • HPAI viruses are more dangerous, can produce high morbidity and mortality in wild birds and poultry, and can sometimes infect humans with serious result. The type of bird flu scientists have been watching closely for the past decade has been HPAI H5N1 (and to a lesser extent HPAI H7s & H9s). 

Before the middle of the last decade, there was no uniform requirement to report or track LPAI infections.  That changed in 2006 when the OIE made reporting of LPAI H5 & H7 viruses mandatory.

The finding of LPAI H7 viruses in wild birds is therefore not terribly surprising, and under normal circumstance would scarcely warrant a mention.   

But with highly promiscuous and mutable clade H5N6 and H5N8 circulating in wild birds across the Korean peninsula, and a very dangerous (albeit LPAI) H7N9 spreading in China, the addition of additional H7 viruses to the mix could complicate matters, either:

  • By directly causing outbreaks of H7 in poultry, as we've seen previously with both of these subtypes in Europe and North America.
  • Or (far less likely) by reassorting with the co-circulating H5 strains, thereby producing new subtypes of avian influenza.

While both are long shots, when the control of avian flu outbreaks are going as badly as they are in South Korea, the last thing they need is an additional complication.

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