Tuesday, September 28, 2021

Czech Republic Reports H5 Bird Flu Outbreak


The last 5 Avian Flu Seasons Compared - Credit ECDC


Every fall, migratory birds which have spent their summers in cooler high latitude nesting regions - and are the primary reservoir host for avian influenza viruses - begin their yearly journey to warmer climes for the winter.  

And so each September, we begin to monitor reports of outbreaks of HPAI along their migratory routes (see map above)

Two weeks ago, in FLI Risk Assessment: Avian Flu Threat High For Germany & Europe This Fall, we looked a the prospects for seeing another bad avian influenza epizootic in Europe, which takes on additional significance after last year's announcement of the first known human infections with HPAI H5N8 (see Russian Media Reports 7 Human Infections With Avian H5N8).

While the risk of transmission to humans is considered low, last May the CDC Added Zoonotic Avian A/H5N8 To Their IRAT List, and we've seen several cautionary reports on the growing zoonotic potential of H5N8 (see V. Evolution: Genomic Evolution, Transmission Dynamics, and Pathogenicity of Avian H5N8 Viruses Emerging in China, 2020). 

While there have already been a few scattered reports of avian influenza in China, and central Russia, today we have the following report from the Czech Republic State Veterinary Agency.

Avian influenza has returned to the Czech Republic, and a new outbreak is in the Příbram region

A new outbreak of bird flu has been confirmed in the Czech Republic after more than four months. It is located in small poultry farming in the village of Trhové Dušníky in the Příbram region in the Central Bohemian Region. The source of the infection is probably wild waterfowl.

The breeder reported the death of five geese from his small breed. There were also 16 hens and 11 ducks in it. Clinical signs typical of avian influenza were observed in one of the ducks. The veterinary inspectors immediately started an investigation in the breeding, took preliminary measures and sent the dead pieces to the State Veterinary Institute in Prague for examination. This subsequently confirmed H5 bird flu. The determination of pathogenicity and the precise determination of the subtype of infection is awaited. The breeder did not rule out that the poultry in the breeding came into contact with wild water birds.

The remaining poultry in the farm was killed this morning. A three-kilometer protection zone and a ten-kilometer surveillance zone will be defined around the outbreak. In these zones, emergency veterinary measures will be announced to restrict poultry movements, inventories of poultry farms and banning of mass events such as stock exchanges or bird shows which pose a high risk of spreading poultry diseases and banning of poultry and bird shows or exchanges. which pose a high risk of spreading the disease.

Avian influenza is a dangerous viral infection of domestic chickens, turkeys, waterfowl, feathered game, exotic birds and wild birds. Avian influenza viruses are commonly found in wild birds and are transmitted mainly through faeces. Therefore, the infection is most often caused by ingestion of feed or water contaminated with the faeces of infected birds. Highly pathogenic avian influenza viruses cause high morbidity and high mortality in birds. In poultry farming, this causes significant direct and indirect economic losses.

The basic preventive measures are (if possible) poultry farming in closed buildings and prevention of contact with wild birds. For holdings where it is not possible to secure an enclosure, measures must be taken to minimize the risk of contamination of water, feed and litter by wild bird droppings, such as placing water and feed under a canopy, preventing poultry from moving in wild water bodies. birds. Another possible measure is the networking of enclosures, etc. Any suspicion of the occurrence of the disease, which is an increased mortality of poultry, a sudden decrease in laying or feed intake, must be reported to the regional veterinary administration.

This year, 37 outbreaks of bird flu in poultry farms and one outbreak in captive birds were gradually declared in the Czech Republic. The first outbreak this year was confirmed on 22 January in small-scale poultry farming in the village of Dlouhá Lhota near Tábor in the South Bohemian Region. Gradually, 37 more outbreaks in farms were added, which were located both in unregistered small farms and in commercial farms. The last outbreak in Mladá Boleslav - Čejetice was confirmed on 18 May. Since July 26, the Czech Republic has been officially free of bird flu.

Petr Majer

Deputy JRC Spokesman
Whether this turns out to be a blip on our bird flu radar, or the vanguard of a new wave of avian flu this winter for Europe, remains to be seen. It is not unusual to see a year-or-two lull in avian flu activity following a big year, like we saw in 2020-2021. 

In addition to last year's H5N8 epizootic, we've also seen a rise in human H5N6 infections in China, the first known Human Avian H10N3 Infection In China, an as-yet unconfirmed report of human H5N1 infections in Nigeria (see The ECDC On The Recent Nigeria H5N1 Report Of Suspected Human Infections).

Avian influenza viruses are constantly changing, and as new clades and subtypes emerge, it is expected that some of these variants will either gain or lose virulence, transmissibility, or biological fitness. Over time, wild birds may become immune to some HPAI strains, or vaccines may alter patterns of spread.

Which means we never know what the next fall migration will bring. While Asia and Europe are at greatest risk, we've seen major avian epizootics strike North America in the past as well. 

Just as in Europe, there is a need to bolster biosecurity here in the United States (see H5Nx: Why North America Must Remain Alert).  

The USDA has some advice on how to Defend The Flock at the website below.

For more on how avian flu strains from Asia and Europe might arrive in North America, you may wish to revisit:

EID Journal: Introduction of Eurasian-Origin Influenza A(H8N4) Virus into North America by Migratory Birds

PLoS One: North Atlantic Flyways Provide Opportunities For Spread Of Avian Influenza Viruses

EID Journal: Reassortment in Wild Birds in Alaska before H5 Clade Outbreaks