Avian Flu Diary: Belgium: Non-Reportable LPAI H3N1 In Poultry

Highlights

LPAI H3N1 Reported On 16 Belgium Poultry Farms - Agriholland

#14,046

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

LPAI viruses are common in wild birds, cause little illness, and only rarely death. They are not considered to be a serious health to public health (LPAI H7N9 being the exception). 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. Again, H5 and H7 viruses are of greatest concern, but other subtypes have also caused human illness and large poultry losses.

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.

While other LPAI subtypes are not currently reportable to the OIE (see Terrestrial Animal Code Article 10.4.1.), that doesn't make them entirely benign.

The most obvious, and worrisome loophole is for LPAI H9N2, which is common in Asia and the Middle East, and has recently moved into Africa.

H9N2 can cause substantial losses in poultry, has jumped to humans on occasion (see FluTrackers List), and easily reassorts with other avian viruses (see J. Virology:Genetic Compatibility of Reassortants Between Avian H5N1 & H9N2 Influenza Viruses).

While the OIE does not require notification on LPAI H9N2 outbreaks, some countries have different local reporting requirements.

There are other LPAI viruses we keep an eye on, including:

LPAI H6N1 which caused a human infection in Taiwan in 2013 - jumped to Taiwanese dogs in 2014, and in 2015's EID Journal: Seropositivity For H6 Influenza Viruses In China, researchers found a a small, but significant number of people in their survey who tested positive for H6 influenza antibodies (indicating previous exposure).
LPAI H4N6 - which while common in wild and migratory birds - has also been found in Chinese, Canadian (1999) and American swine (see Virology: Detection & Characterization Of Avian H4N6 In Midwestern Swine (2015)) and has shown signs of human adaptation (see Cell: Avian-to-Human Receptor-Binding Adaptation by Influenza A Virus Hemagglutinin H4).

For the past two weeks there have been reports of LPAI H3N1 being detected on farms in Belgium, raising concerns in neighboring countries (see April 24th's Low pathogenic avian influenza H3N1 on 7 Flemish poultry).

According to local reports, the impact of this H3N1 infection on poultry has been unusually high, raising concerns. This from the Flemish Information Center for Agriculture and Horticulture.

Poultry worried about low pathogenic avian influenza

( Translated Excerpt)

Because it concerns the low pathogenic H3 variant of the bird flu virus, no legal measures must be taken. The legislation only stipulates that measures must be taken in the event of outbreaks of highly pathogenic bird flu or in the case of the low pathogenic H5 and H7 strains.

Because the mortality is high and there is a clear decrease in production of laying hens, both Boerenbond and De Landsbond call on poultry farmers to take the highest biosecurity measures into account. For example, it is not advisable to give people who are not necessary for operational management access to the stables. For all external vehicles that arrive at the company, for example from the feed supplier or from Rendac, it is recommended to disinfect the wheels and wheelhouses.

The organizations are currently in close consultation with the Food Agency to see if there is possibly a co-infection involved that could explain the high rates of chickens. It is also being examined how the virus can spread so quickly despite strict biosecurity measures.

(Continue . . . )

H3N1 is also a concern because H3 viruses have a long history of infecting humans, horses, dogs, and other mammals. The progression of human influenza pandemics over the past 130 years is believed to have been H2, H3, H1, H2, H3, H1, H1 . . .

H2N2 sparked two pandemics (1898 and 1957) roughly 69 years apart.
H3 viruses unleashed two pandemics (1900 and 1968) roughly 68 years apart
And H1N1 caused the great 1918 pandemic only to return in the pseudo-pandemic of 1977, 59 years later (and then reinvented itself in the 2009 Pandemic).

This repeating pattern of the H1, H2, H3 pandemics is hard to ignore, even if the sample size is small (see Are Influenza Pandemic Viruses Members Of An Exclusive Club?).

While there is currently no evidence to suggest that this LPAI H3N1 virus in Belgium poses any sort of human health threat, anytime we see an avian flu virus acting in an unusual manner, it bears watching.

Some recent blogs on H3N1 and other H3 viruses in the wild include: