Category Archives: Animal Health

Shower On, Shower Off

“What’s this got to do with chickens?” I hear you say.

Well, in some parts of the chicken production business, quite a lot!

Why? Because it’s one of the many biosecurity measures that may be implemented by industry to protect flocks from infectious disease.

What’s biosecurity?

From a chicken industry perspective, biosecurity refers to a set of preventative measures designed to stop the introduction and subsequent spread of diseases, thereby protecting flocks, individual farms and the industry more broadly from the impacts of infectious diseases (see more at http://www.farmbiosecurity.com.au/). They also aim to prevent the spread of other pathogens that could potentially have human health consequences. Therefore, biosecurity is all about keeping the chickens, and people, free from disease or illness.

The chicken industry has had in place for many years a detailed set of procedures to manage biosecurity risks on farms (see National Farm Biosecurity Manual for Chicken Growers), and implementation of biosecurity practices is a part of everyday business for an Australian chicken farm.

What sorts of biosecurity measures does a chicken farm implement?

There are a range of measures that would typically apply on an Australian chicken farm. They include:

  • Limit contact with other animals (particularly other poultry and wild birds), for example by bird-proofing chicken barns with wire netting or, on farms which have access to an outside range, by ensuring the range, as far as possible, does not attract or provide habitat for wild birds or rodents, for example by keeping the range tidy, well drained, and the grass mown to prevent seeding…oh yes, and not leaving feed and water out on the range!
  • Make sure feed and water is clean and uncontaminated, for example by only using town water, or treating (eg by chlorination) any otherwise untreated surface water (such as from a dam or river) that might be used on the farm.
  • Limit vehicle/equipment movements onto and around the farm, and clean and disinfect equipment that has might have been on another farm prior to farm entry (and particularly entry into the areas where the chickens live).
  • Limit risks of people bringing disease and pathogens onto the farm and contaminating the chickens. That’s right – people present a significant biosecurity risk themselves; they can bring in disease on to farms on their hands, hair, skin, clothing and footwear…even potentially in the breath they exhale! Here’s some examples of what farmers can (and do) do to reduce this risk:
    • limit visitors, and control visitor movements;
    • make sure that staff, contractors and visitors have not had recent contact with other poultry farms or birds (including at home);
    • require any farm visitors to change into freshly laundered clothing and footwear on the farm, or to put on protective coveralls and over-boots prior to entering a barn or range area;
    • anyone entering a barn (including the farmer and staff) to use disinfectant foot baths and hand washes at the barn entry.

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And what about those showers?

Well, in those parts of the chicken production cycle where disease presents the greatest risks to the total operation – for example, breeder farms, which supply the fertile eggs which are hatched to produce the chickens that might ultimately go out onto many, many farms; or at hatcheries, where an infection could likewise be spread to very susceptible baby chicks with as yet incompletely developed immune systems, and which may also end up going out to many, many farms – even more stringent biosecurity measures need to be implemented.

One of these is usually that any staff and visitors to the facility can only enter through a shower facility where they must have a complete head to toe shower and change into a complete new set of freshly laundered clothing provided by the facility on the other side, with no personal items to be taken onto the facility, without prior decontamination. In the case of some extremely biosecure facilities, the process must be repeated again on the way out. A visit to one of these facilities can result in a very bad hair day for many visitors – I’ve done it, so I can speak from experience here!

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Is the system infallible?

No – chicken farms contain many live animals; they receive fresh air from the ambient area (which can also carry airborne microorganisms) and have many contacts with the world outside the farm; they are working farms, not containment facilities. So equally important in the industry’s health program are other preventative measures, such as vaccination and farm hygiene, and being able to recognise and immediately respond to signs or suspicion that something may have breached biosecurity barriers. Together, biosecurity, other preventative measures and actions (including vaccination), and the ability to recognise and preparedness to respond to a disease, are the most important tools the Australian chicken industry has to keep its flocks healthy and safe from diseases and pathogens.

For those interested in learning more about what biosecurity means for the chicken industry, and what practices are adopted, there will be a new biosecurity video available in the coming months…I’ll let ChookChat followers know when it’s released.

Avian Influenza – what’s the latest?

Have you noticed that Avian Influenza (AI) has been in the news a lot lately? This is largely due to the unprecedented spread of outbreaks, primarily in poultry flocks, around the globe over the past six months.

Fortunately, Australian poultry flocks have to date escaped this wave of AI, but sadly AI is currently having devastating consequences for the poultry industries in many other countries. For example, the US poultry industry has been particularly hard hit, at last count having AI confirmed on over 200 separate locations since December 2014, affecting almost 47 million birds. The disease has mostly been in turkey and egg farms, and has spread from the Pacific Northwest and California through to the mid-west states such as Montana, North and South Dakota, Minnesota, Iowa and beyond, with the strain of virus evolving as the outbreak has spread (to follow the course of this outbreak in the US, the following site is a useful one to watch: https://batchgeo.com/map/2015-avian-influenza-outbreaks).

So what is avian influenza? Where does it come from, and what are the risks and consequences of our poultry flocks being infected with it? Read on…

What is avian influenza?

Avian influenza is an infectious disease of birds caused by a Type A influenza virus. So, just like humans, birds, including chickens, can get the ‘flu!

However, the types (strains) of influenza virus that can cause disease in birds are generally not the same types that cause the flu in humans, as I’ll explain below.

All about Avian Influenza

What is Avian Influenza?

What’s in a name?

Not all influenza viruses are the same. Some have a greater affinity for infecting and/or causing disease in certain host species than in others, and some types cause worse disease in their favoured host species than other types.

Influenza A viruses are divided into subtypes based on the structure of two proteins on the surface of the virus – the hemagglutinin (H) and the neuraminidase (N) proteins. There are at least 16 different H subtypes and 9 different N subtypes. Each virus has one of each subtype in any combination, and influenza A viruses are named accordingly eg H1N1; H5N2 etc.

Some subtypes cause disease in certain species of animals and not others. For example, most of the viruses that are responsible for seasonal flu in humans are H1 or H3 subtypes.

On the other hand, while most subtypes can be carried by wild birds, the two subtypes that are capable of causing serious clinical disease in poultry flocks are H5 and H7. Conversely, these two subtypes are rarely associated with disease in humans.

Strains of influenza virus found in birds are further divided into two groups based upon the severity of illness in birds they cause: low pathogenic (LP) and highly pathogenic (HP). Low Pathogenic avian influenza (LPAI) infection typically only causes minor illness – indeed, sometimes infected birds show no clinical signs at all. Highly pathogenic avian influenza (HPAI), on the other hand, is highly infectious and causes severe disease and often high mortality rates, particularly in chickens and turkeys.

Where does avian influenza come from and how does it spread?

Avian influenza viruses are commonly carried by wild birds, particularly waterfowl such as ducks and geese. In Australia, ongoing surveys of wild birds show that a small proportion of wild birds show evidence of having been exposed to avian influenza virus (for example, see https://rirdc.infoservices.com.au/items/15-016). Generally, wild birds carry the low pathogenic forms of AI viruses (indeed, in Australian wild bird surveys, all AI viruses found have been LPAIs).

However, infections can be spread from wild birds to poultry flocks, either through direct contact, or indirectly, for example through contamination of a flock’s water supply or the range which the flock has access to by wild bird droppings.

Once in a flock of highly susceptible poultry species such as chickens or turkeys, some LPAI virus strains are capable of mutating into their HPAI form, giving rise to outbreaks of clinical avian influenza disease. Thereafter, spread to other poultry flocks can occur through wild birds movements or by other mechanical means, like through movements of infected poultry, or contaminated equipment shared between poultry farms.

Do we have it in Australia?

Many people may be surprised to learn that we have had 7 outbreaks of high path avian influenza in Australian poultry flocks over the course of the past four decades, the most recent being in layers (chickens raised to produce table eggs rather than chicken meat) in Young in 2013. The reason you may not recall having heard about these, is that on each occasion the initial infected flock was quickly identified, reported to authorities and acted on to eradicate the disease, so that there was no opportunity for significant further spread.

Does AI affect people?

It is extremely rare for strains of avian influenza virus that cause disease in poultry to also cause disease in humans. For example, despite the extent of the current outbreak in the US referred to in my first paragraph, the number of properties affected and the numbers of birds infected, the strains involved are not known to cause disease in humans and no humans have been affected. Similarly, none of the strains associated with outbreaks in Australian poultry flocks have been known to cause illness in humans.

However, some strains of H5 and H7 avian influenza viruses found overseas have been able to occasionally infect people (for example, the H5N1 strain that many readers may recall having attracted much media attention over the past decade), but this is rare, and requires very close physical interaction with infected birds.

Can you catch it from eating chicken?

NO! The World Health Organisation confirms that properly cooked chicken meat cannot transmit AI.

What are we doing to keep AI out of Australian flocks?

Well, at a farm level, the Australian chicken industry implements biosecurity procedures on farms largely aimed at reducing the risk of transmission of viruses from wild birds to commercial flocks.
Constant vigilance is important too – the industry has arrangements in place for monitoring the health of flocks and a system for reporting unusual or suspicious health issues to both company veterinarians for investigation and onward reporting to government authorities.
In the event of confirmation of a case of AI, we also have a well rehearsed and up-to-date response and management plan in place which has been agreed to by both industry and governments to ensure a rapid response to an outbreak. Those outbreaks we’ve had over the past 40 years have given us the chance to test and refine the plan, so that we know it works!

For more information on Avian Influenza from an Australian perspective, see the the ACMF website: http://www.chicken.org.au/page.php?id=170. The ACMF website also answers a range of FAQs related to AI on a dedicated webpage: http://www.chicken.org.au/page.php?id=151