It was less than two months ago that FAO issued a warning that H5N8 avian influenza virus had been detected in wild birds in Tyva Republic in southern Russia and would likely spread in a south-westerly direction with the autumn migration of waterbirds. The virus, which is highly pathogenic for poultry, appears already to have travelled westward as far as Poland and Hungary, and southwards to Kerala Province in India, according to recent official notifications to the World Organization for Animal Health, or OIE.
“Events in the past week demonstrated that the virus has already spread from wild birds to domestic poultry,” said FAO chief veterinary officer Juan Lubroth. The H5N8 virus has been detected in wild birds as well as domestic ducks in four States of India, and in Hungary, in a swan found dead in the southeastern part of the country, and a turkey flock in Totkomlos.
The dead Mute Swan in Hungary was found in late October near saline soda Lake Fehér-tó in Csongrád County, a well-known resting place for migratory birds, according to Andriy Rozstalnyy, FAO animal production officer for Europe and Central Asia. Hungarian authorities have now identified the virus as very similar to that found in wild birds at Lake Ubsu-Nuur, Tyva Republic in Russia in June. The locations – in Hungary and India – correspond roughly to the fall migration patterns of waterbirds, particularly Anatidae species.
Earlier this week (7 November) an H5N8 highly pathogenic avian influenza (HPAI) virus was also confirmed in wild birds in Poland. Though virological information is still awaited to confirm that it is the same strain, it is highly likely.
These recent detections of H5N8 virus in wild and domestic birds are additional evidence of the role of wild birds in the long-distance movement of H5 HPAI viruses from one stopover location to another along their migration routes. This appears to be the fourth documented wave of intercontinental movement of such viruses since 2005. The role of wild birds in their long-distance movement is now incontrovertible, according to a recent FAO news bulletin and other scientific publications.
Countries across the region should be on high alert for incursions of the virus, should adopt stronger biosecurity measures on all poultry farms, and enhance their surveillance, said Roztalnyy. All countries along the migratory pathways of the Anatidae family of birds are at risk, including countries of the Middle East, the European Union, West Africa, the former Soviet Union, and South Asia.
“We cannot predict which countries will experience outbreaks in poultry or cases in wild birds,” Rozstalnyy said, “but all should consider measures to curtail the disease and prevent spread of the virus in poultry.” The risk extends through March-April 2017 for Europe and the Middle East, he noted.
- FAO is calling for increased testing of any wild birds found dead or shot during hunting activities, and for vigilance on the part of poultry owners near sites where waterbirds congregate.
- Gene sequencing should be performed for all H5 viruses detected, and results shared with the global community in a timely manner. This will aid understanding of how the virus is spreading
- Hunting, handling and dressing of shot waterfowl in areas where H5N8 is likely to be circulating (as is currently the situation in Europe) carries the risk of spreading avian influenza viruses to susceptible poultry.
- Commercial poultry operations and backyard poultry owners should avoid the introduction of pathogens through contaminated clothes, footwear, vehicles or equipment used in waterfowl hunting.
- Any waste from hunted birds should be treated as potentially contaminated and safely disposed of.
Waterbird scraps should not be fed to domestic animals (cats, dogs, or poultry).
Action on wild birds not recommended
There is no benefit to be gained from attempting to control the virus in wild birds through culling or habitat destruction, FAO cautioned. Nor is there any justification for pre-emptive culling of endangered species in zoological collections.
Control measures for captive wild birds should be based on strict movement control, isolation and only when necessary limited culling of affected flocks, according to FAO.
There is no long-term carrier status of H5 avian influenza in wild or domestic birds. Use of disinfectants should be focused on areas with no accumulated organic matter, and which have been cleaned. Spraying of birds or the environment with disinfectant – for example sodium hypochlorite or bleach – is considered potentially counter-productive, harmful to the environment, and not effective from a disease control perspective.
Public health significance
While highly pathogenic for domestic poultry, the human health risk of the Tyva 2016 strain of H5N8 virus is probably low, according to available evidence. To date, no cases of Influenza A in humans caused by avian influenza viruses have been associated with H5N8 viruses. Nevertheless, FAO is making the following recommendations:
- dead birds should not be handled or prepared for food
- authorities should be notified of any mortalities
- bird carcasses should be properly disposed of 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
- any poultry product for consumption should always be thoroughly cooked.