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Disease and ostrich confinement

Eduardo Carbajo
Previously confinement was only for ostrich chicks (of all ages) at night to prevent them from getting too wet and developing hypothermia (Mitchell, 2001). However, the recent outbreaks of avian influenza have triggered a new reason for ostrich confinement, disease prevention (Huchzermeyer, 2006)

Previously confinement was only for ostrich chicks (of all ages) at night to prevent them from getting too wet and developing hypothermia (Mitchell, 2001). However, the recent outbreaks of avian influenza have triggered a new reason for ostrich confinement, disease prevention (Huchzermeyer, 2006 )
By confining ostriches indoors contact is avoided with wild birds, in particular waterfowl, which are possible sources of infection. An ostrich enclosure should be well lit, have sufficient space, allow the ostrich to look outside and facilitate guarding behaviour. It is important to realise that confining ostriches indoors is stressful for them but it is always preferable to losing them to avian influenza. Of course the need for confinement is dependent on the regulations set out by each country. European Union member states:
• After a suspected or confirmed case of avian influenza; protection/ surveillance zones and risk areas are formed which in turn justify temporary confinement. Without this exceptional situation, confinement could be classed as suffering for the ostriches, which is not allowed by European Convention for the protection and keeping of animals for farming purposes.
• There have been no cases or risk areas formed where strategies have been suggested for avoiding confinement; such as, permitting preventive vaccination, considering the ostrich as a rare or exotic bird or applying a surveillance programme with serological test samples.
Currently there is no exceptional scientific data on vaccinations in ostriches and any extrapolation from data on other species should be accompanied by preliminary studies. There has only been one trial in ostriches using commercial unspecific vaccines to determine the immune response as measured by serology (HI-method) and not correlated with protective immunity. It was concluded from this trial that vaccination did not produce specific immune protection. So the discussion is now, if the possible effectiveness of vaccination can be due to a much higher amount of infectious virus required to produce infection after induced resistance.
Ostrich producers believe that vaccination is of great importance because of the difficulties involved with indoor confinement, but in the EU vaccination may result in regional or total suspension of export for ostrich products. In Northern Spain there has only been one confirmed case of waterfowl (Podiceps cristatus) with avian influenza that was in 2006. A risk area was formed locally and preventive vaccination was not applied. Whereas, in Central Spain, Madrid, forced confinement of birds in backyard farms and parks was implemented. Fortunately for ostriches, forced confinement was not implemented; serological samples were taken and tested for avian influenza.
Note: Improve your facilities - see Recommendation Concerning Ratites 1997 , appendix 6; place water and feed troughs inside to avoid contamination from feeding wild birds, also be on the alert for signs of infection for example the excretion brilliant green urine.
 
Question
: In the event of an avian influenza outbreak, can you suggest, other than those mentioned above, other strategies to avoid ostrich confinement?


7 comments

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    A reader

    Thanks for your blog. Wild birds play an important role in spreading AI viruses but they are NOT the only factor. There are many other factors which may contribute to AI outbreaks.
    In my opinion, confinement is NOT the only solution. Vaccination might be of help.

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    Rayan A. Haydar

    Ostrich production & rearing will differ from one region to another, for example in Saudi Arabia, Ostrich confinement (except for chicks) will be very difficult leading to more stress , even mortality in birds due to high temperatures. Any indoor ventilation system will be very expenses & will increase the levels of humidity inside the sheds (the birds will become very wet because of the use of desert coolers and misters); the risk of CRD occurrence will become higher and the spreading of any disease in case of confinement will be faster between birds.
    In case of AI Outbreak, I suggest a semi closed system, where birds, will only have a partial space to move in. Food & water will be limited to morning hours, with daily cleaning & disinfection applied to the troughs, sheds & runways. Watchman must remain close to the pens for proper observation. Monthly Fast AI tests must be applied & if needed, blood tests every 90 days to insure that the birds are free from AI.
    I do not have any reliable literature on AI vaccines applied on Ostriches, but if such vaccine becomes available & provide the birds with the required immunity, I will strongly support its use. We just cannot continue culling ostriches indefinitely.

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    Dr Ross G Cooper

    Some important discursive issues have been raised by the author. Well done.

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    Stan Stewart, Chairman, World Ostrich Association

    The meat from birds with bird flu is still safe to eat so does not affect food safety. Bird Flu is therefore largely an economic disease and producers should therefore be enabled to protect their flocks in the same way as they would for other diseases – by vaccination and the establishment of good management practices. The vaccine industry would have to make considerable efforts to keep up with the latest mutation but if vaccination was routinely carried out throughout the world there would be plenty of incentive for them to do so. If farmers were provided with this weapon against their birds contracting the disease then governments could legitimately allow the cost of protection to be borne by the industry through the higher production costs that would in turn be passed on to the consumer.

    With regard to ostrich, there has not been a single recorded instance to date of an ostrich being infected by the H5N1 strain of the virus. Some ostriches have been slaughtered as part of a contiguous cull of other affected fowl but none have been shown to have the disease in their own right. So there is good reason to be hopeful that ostrich are not affected by this particular strain of the virus and worthy of further investigation. The AI virus can spread very rapidly through densely populated poultry houses but it seems to be quite difficult to catch by birds that are kept in more extensive situations, especially if the birds are well fed and healthy prior to infection. If birds cannot come into physical contact with other infected birds (by being in separate pens) and especially are prevented from eating the droppings of infected birds, there is a greatly reduced chance of them catching the disease.

    I disagree that ostrich should be housed to prevent them coming in contact with the disease. Permanently housed ostriches, especially breeder birds will be at great danger to each other from fighting and should never be kept in large enclosed groups for extended periods. With grower birds up to the age of about 20 weeks there is less of a problem but from then on these will also start to fight for dominance with the resultant economic damage to the skins. It is of course sensible to feed and water indoors and to have excellent bio-security measures in place. The World Ostrich Association have published guidelines specific to ostrich. These can be viewed at: http://www.world-ostrich.org/avianinf.htm. The most practical solution to keeping all birds safe from contracting AI is to introduce world-wide vaccination as a matter of course.

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    Rayan A. Haydar

    The commercial production of Ostriches remains a young science, with very little improvements taking place. The Ostrich production all over the world is shrinking & very few remaining producers are struggling to survive.
    With the threat of AI, the risks are becoming higher and more difficult to meet. The confinement may sometimes be the only solution in cases of serious outbreaks, but cannot be implemented easily because of the nature of the birds & the higher possible rates of injuries. If we take the case of Saudi Arabia, Ostrich Confinement is not possible because you require controlled environment inside the shed (very high temperatures), which is very expensive to have, not mentioning the increased possibility of CRD in closed systems with higher humidity levels. Furthermore, vaccination for AI is still debatable and with no conclusive results for acquired immunity.
    What I can suggest is a semi open system that will limit the bird exposure and movement, in such system, the possibility of contact with wild birds will be much lower, access to feed and water must restricted during the night & the feed troughs must be cleaned and disinfected every day prior and post feeding. Such systems will only succeed if it is supported by proper
    Bio-security measures & close monitoring of the birds with monthly serological tests randomly collected from pens. Such Management practices will only reduce the possibility of infection, but will never provide a 100 % protection.

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    Adriaan Olivier

    A few comments on ostrich immunity and the AI situation:
    Ostriches are not big chickens and it seems their immunophysiology is more closely related to reptiles than avians.
    This means measured HI titers may have a poor correlation to protective immunity.
    Birds exposed to virus may show hig resistance to establishment of infection dispite poor/ low HI measured humoral immunity.
    More birds will be lost to confinement than AI challenge it seems as I agree that confinement is extremely sressful.
    Ostriches are also more likely to be infected via waterborne sources of AI than the classical coprophagia (fecal/oral) route.
    What the current situation does clearly show is that if you add two very much unknown/ unstable variables (viru sand host) to disease equation you may never know what may pop out.

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    michael SUNDERLAND

    I find Dr COOPER'S point that the Ostrich (Ratite)is more closely related to reptilians very interesting.Clearly the species is distinct from Poultry or Ruminant Animals, yet when a milder H7N3 virus occurred in Poultry in Saskatchewan in September Ostrich imports were included in the 90 day Import ban imposed on Canada.I wonder how and why Ostrich got to be included?.
    The evidence I see with H5N1 is that it is waterborne and its path follows the natural waterways of the world.The Commercial exchange of Livestock may be another cause.
    Assuming that all Ostrich Farms are providing fresh and clean drinking water daily the risk to A.I is low, the issue that would concern me is the Birds go into a shelter or barn to drink.Such buildings must be kept open for ingress and egress but have a higher risk from contamination from the wild bird population that visit the building.Placing water points on the fenceline in an open place away from trees and other buildings may be a better option.As we do not have a case of A.I it is very difficult to understand why a vaccine is neccesary and without a live culture from an infected bird it must be important to determine how the disease would mutate in Ratites before issuing vaccines.There is already a tendancy to resort to Pro Biotics and now Vaccines, are we really ready to destroy a Natural healthy Meat Source by adding potential contaminants for Human consumption?.

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