Monday, November 07, 2016

FAO On HPAI H5's 4th Intercontinental Wave


Although it was released before Friday's announcement from Hungary: HPAI H5N8 Detected At A Turkey Farm, we've a cautionary report from the FAO on the emergence of HPAI H5N8 in both India and Hungary over the past couple of weeks.

This is the second major H5N8 warning issued by the FAO in the past two months (see FAO/EMPRES: H5N8 Clade Detected Over Summer In Russia).

When combined with their recent dispatch over H5N1 (see FAO EMPRES: Risk Assessment For Spread Of H5N1 In The Middle East), we've strong indications that HPAI H5 is on the ascendant once again.

The first great diaspora of HPAI H5 occurred between 2005 and 2007, when H5N1's territory jumped from a handful of Southeast Asian countries to more than 60 countries across Asia, Europe, the Middle East and Africa.

For reasons that aren't fully understood - starting in 2008 - the virus began to give up some of its new found territories, but remained firmly entrenched in Indonesia, Bangladesh, India and Egypt.

H7N9 emerged in China in 2013, and quickly rose to the top of our avian flu threat list, where it remains today. It has sparked four winter waves of human infection in China thus far, and is expected to return again this winter.

Since 2014, however, we've also seen a new resurgence of HPAI H5N1 in Western Africa, Eastern Europe, and parts of the Middle East, the emergence and spread of HPAI H5N6 in China, Laos and Vietnam, and the emergence and global spread of HPAI H5N8.

Additionally, after more than a dozen years of vigorous debate, the evidence on the role of Migratory Birds & The Spread Of Highly Pathogenic Avian Flu has become increasingly clear.

And as we've discussed previously, while there are two annual bird migrations (spring and fall), a recent report (see Sci Repts.: Southward Autumn Migration Of Waterfowl Facilitates Transmission Of HPAI H5N1) pegs the fall migration as the biggest risk for the spread of HPAI by migratory birds.

All of which brings us to this report from the FAO, which calls this the `fourth wave of intercontinental movement of H5 HPAI virus since 2005' and warns that other countries in Europe, the Middle East, Asia, and Africa are at risk of seeing H5N8 arrive in the months ahead.

H5N8 highly pathogenic avian influenza detected in Hungary and in the Republic of India

04 November 2016 - On September 14, FAO EMPRES issued a warning about an H5N8 highly pathogenic avian influenza virus that had been found in Tyva in the Southern Russian Federation.  It was expected  (based on earlier events over the past 11 years) that this virus would likely be found in other locations to the west and south in the following months.

Events in the past week strongly suggest that this may be occurring with an H5N8 virus now detected in four states of India and also in Hungary (a dead swan in South East of the country). So far, genetic information is not available on the viruses in these two locations but the timing is generally consistent with previous events and corresponds broadly with the Autumn migration and movement patterns of wild Anatidae (family of birds that includes ducks, geese, and swans).

Four aspects of these developments are worth noting.

1. The two cases add additional evidence of the role of wild birds in the long distance movement of H5 highly pathogenic avian influenza viruses

This appears to be the fourth wave of intercontinental movement of H5 HPAI virus since 2005. The role of wild birds in the long distance movement of these viruses is  now incontrovertible.
Clearly additional genetic information is required to confirm that the virus found in India and Hungary is essentially the same strain as that found in the Tyva Republic, but the pattern of cases in India and species involved in Hungary still support a role for wild bird introduction.

The precise origin of the Tyva 2016 H5N8 virus remains unknown although available evidence suggests it was derived from earlier H5N8 viruses detected in Eastern China (WHO 2016). The virus is readily distinguishable from strains of H5N8 virus found in Europe and North America in 2014-15.
2. Other countries should be on high alert for incursions of this virus and should adopt stronger biosecurity measures on all poultry farms and enhance surveillance

A range of countries along migratory/movement pathways of Anatidae remains at risk. Although it is not possible to predict which countries will experience outbreaks in poultry or wild birds, any of the countries listed below should consider measures to curtail the disease and prevent spread of virus in poultry. The risk extends through to March/April next year for Europe and the Middle East. Testing of dead wild birds and poultry in areas near to migratory concentration points should be increased.

The genes of all H5 viruses detected should be sequenced and results shared with the global community. This information is crucial in helping to understand how virus is spreading. It applies to viruses detected in India and Hungary as well as viruses elsewhere in the region such as those causing death of quail in the United Arab Emirates in early October.

Places at Risk:

    Countries in the Middle East;
    Countries in the EU;
    West Africa;
    Countries in the former Soviet Union;
    Countries in South Asia.

3. Action on wild birds is not recommended

There is no benefit to be gained in attempting to control the virus in wild birds through culling or habitat destruction. There is also no justification for any pre-emptive culling of endangered species in zoological collections. Control measures for captive wild birds in places where virus is detected should be based on strict movement control, isolation and only when necessary limited culling of affected birds. There is no long term carrier of H5 avian influenza. Use of disinfectants should be focused on areas with no accumulated organic matter that have been cleaned. Spraying with disinfectant of birds or the environment in which birds are found is ineffective and potentially counter-productive.
4. Public health significance

Available evidence suggests that the human health risk of the Tyva 2016 strain of virus is likely to be low. So far no cases of Influenza A in humans caused by avian influenza viruses have been associated with H5N8 viruses.
Nevertheless, dead birds should not be handled or prepared for food. Authorities should be notified of any mortalities and proper disposal of carcases conducted after sample collection. Standard hand hygiene practices should be followed by anyone who might come in contact with bird droppings or dead birds. Swimming in water that is potentially contaminated should be avoided. All poultry products for consumption should be cooked thoroughly at all times.

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