Avian flu

Aviäre Influenza

Changed on: 08.03.2021
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The pathogens causing avian flu (bird flu or avian influenza) are influenza viruses. They are divided into types A, B and C. Influenza virus A has different subtypes, which are caused by different surface antigens (neuraminidase - N; and haemagglutinin - H). New variants of influenza viruses constantly emerge as a result of genetic modifications. So far there are 16 haemagglutinin and 9 neuraminidase subtypes.

Occurrence

Avian influenza or bird flu was first observed in Italy in 1878. The pathogens occur worldwide.

Reservoir

Influenza A viruses of subtypes H5 and H7 are found in chickens, turkeys and numerous wild bird species. Ducks, geese and other wild birds either have little or no symptoms, but are important for the spread of the virus.

Mode of transmission

Avian influenza is highly contagious for poultry. The virus is excreted in faeces, saliva and tear fluid. If there is a lot of dust, indirect infection via air is also possible.

Symptoms

The distinction between highly pathogenic and low pathogenic AI types refers to the severity of the disease in birds: while low pathogenic AI types cause no or only mild symptoms, highly pathogenic AI types cause severe disease progression and high mortality rates.

Situation in Austria

Since April 2017, no case of avian influenza (HPAI) has occurred in Austria, neither in domestic nor in wild birds. Due to a large number of outbreaks close to borders in Europe, the likelihood of avian influenza entering Austria is increasing and poultry keepers are advised to pay increased attention. However, avian influenza does not pose a risk to humans and is not transmitted via food.

Risk areas in Austria

In Austria itself, no case has been reported so far. Nevertheless, the risk of an outbreak is assessed as high. In close coordination with the federal ministries (BMSGPK, BMLRT), the provinces, AGES, the Austrian Quality Poultry Association (QGV) and the Central Working Group of the Austrian Poultry Industry (ZAG), preventive measures will be implemented in the risk areas by decree from 7.12.2020. For the designation of the risk areas, among other things, the proximity to the positive wild birds in Bavaria (Passau), the location along river courses and lakes, where already during the then avian influenza 2016/2017 positively tested wild birds were found, were taken into account.

Catalogue of preventive measures

In these areas it is necessary to keep poultry away from wild birds. This will help to prevent the outbreak and prevent damage to poultry farmers. For the risk areas in Austria, the following measures apply to poultry farmers:

  1. In mixed holdings, keep ducks and geese separate from other poultry.
  2. Keep poultry in sheds or in enclosures covered at the top.
  3. Exception from keeping poultry in sheds: if poultry are protected from contact with wild birds by nets, roofs, horizontally placed fabric or other suitable means, or if feeding and watering of the birds is carried out only in the shed or in a shelter which prevents, as far as possible, the access of wild birds.
  4. Wild birds must not come into contact with feed or water intended for the poultry. Outlets must be fenced off from surface water where wild waterfowl may be present.
  5. Increase sanitary safety measures: Cleaning and disinfection with special care.
  6. The authority (the official veterinarian) must be notified if there is a drop in feed and water intake of more than 20%, a drop in egg production of more than 5% for more than two days or if the mortality rate is higher than 3% in one week.

Due to the onset of winter it is also to be expected that there will be an increased occurrence of wild birds found dead. Wild birds and waterfowl found dead are to be reported to the official veterinarian.

Information of the Ministry of Health on avian influenza

Results of surveillance in Austria

In 2019, a total of 3,478 blood samples were tested for avian influenza virus. All samples were negative. The Europe-wide surveillance programme consists of an active (commercial poultry) and a passive (wild birds) part. In the 2019 active surveillance programme, slaughter blood from 1,250 laying hens from 125 farms (of which 63 were free-range), 390 parent hens from 39 parent farms, 530 turkeys for fattening from 53 farms, 1,215 geese and ducks from 65 farms and 93 ostriches from 17 farms arrived for serological testing. No antibodies to AI virus were detected. Also, 200 poultry samples that were additionally tested for the AI virus genome were negative. During passive surveillance in 2019, 84 samples from wild birds found dead and 1 live were tested for the avian influenza A virus genome. No pathogenic AI viruses were detected in 84 and 1 dead wild bird was found to have nonpathogenic AI virus.

Avian influenza last occurred in Austria in 2016/17: HPAIV H5N8 was detected on two farms. The two outbreaks (10.11.2016, 17.01.2017) in Vorarlberg and Burgenland had in common with Lake Constance and Lake Neusiedl the immediate proximity to the lake and positive wild bird findings in the immediate vicinity. In the provinces of Salzburg and Upper Austria, HPAIV H5N8 was also detected in wild birds in the lake regions, but disease spreading into farms did not occur. Since then, no HPAI virus has been detected in Austria.


Legende

    Situation in Europe

    In January 2020 avian influenza was detected in poultry in Poland, Slovakia, Hungary, Romania, the Czech Republic, Germany and Bulgaria. The virus type H5N8 was detected in the infected animals.

    Since the end of October, cases of avian influenza (HPAI) have reappeared in some European countries (Germany, Netherlands, Belgium, Denmark, Sweden, Ireland, United Kingdom, France) in wild birds, but also in domestic poultry flocks.

    Currently, outbreaks have been reported in Croatia and Bavaria, increasing the risk of an outbreak in Austria.

    The subtype H5N8 has been detected. To date, there is no known case worldwide in which the H5N8 virus has been transmitted to humans.

    Professional information

    Veterinary Medicine

    At the National Reference Laboratory for Avian Influenza, samples (organs, swabs, carcasses) are examined for direct virus detection by real-time RT-PCR, sequencing and with egg culture and haemagglutination test (HA). The indirect detection by determination of antibodies is done by ELISA and haemagglutination inhibition test.

    Haemagglutination test: Certain viruses such as influenza viruses bind erythrocytes to their surface via haemagglutinin. This causes the blood to clump together (agglutination). The amount of virus can be determined by dilution series.

    Haemagglutination inhibition test: Specific antibodies can prevent agglutination/clumping caused by the virus. In this way antibody titres and individual virus strains can be determined.

    ELISA: Enzyme-linked Immunosorbent Assay is an antibody-based detection method, antibodies bind to an antigen and are detected by an enzymatic colour reaction.

    Real-Time RT-Polymerase-Chain-Reaction (PCR) and sequencing: AI virus gene sequences are detected and H5 or H7 types can be distinguished directly. The pathotype of the virus strain (high or low pathogenic) can be determined by sequencing.

    Egg culture: A potentially infectious vaccination solution is prepared from the samples, which is used to inoculate virus-free chicken eggs. These eggs are incubated for at least five days. If highly pathogenic avian influenza viruses are present, the embryos in the eggs die and the virus in the allantios can be identified by haemagglutination (HA).

    Contact, forms

    Institute for Veterinary Medicine Mödling

    Robert Koch-Gasse 17
    2340 Mödling

    Phone: +43 50 555-38112
    Fax: +43(0)5 0555 38529
    E-Mail: vetmed.moedlingno@Spam@agesno.Spam.at

    Suspected cases of epidemic outside opening hours by telephone:
    Phone: +43 664 9670940 or +43 664 8398216.

    Opening hours and delivery of samples:
    Monday - Friday: 7.00 - 15.00
    Outside office hours, urgent samples can be delivered to the porter with a valid form, indicating the client.
    E-mail address of the diagnostic information: servicezentrale.moedlingno@Spam@agesno.Spam.at

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