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Dr Brendan Sharpe

Internal parasites in poultry will focus mostly on round worms, which infect the intestines and coccidiosis, which is caused by a protozean parasite that also infects the intestines.

We find that susceptibility of poultry to coccidiosis and worms is very much age dependent and chickens, probably in the first month to two months of age are most susceptible.

Adults generate an innate resistance to both of these parasites.

Round worms, the life cycle starts with the chook ingesting an egg. The egg then hatches the worm hatchling, lives within the intestine, grows, feeds on secretions and cells from the fowl. That mature worm then secretes eggs which go out into the poultry faeces so to continue the life cycle.

The damage caused by the feeding and the residing of the worms in the intestine causes enteritis, which is inflammation of the intestine, and that presents as diarrhoea but also ill-thrift or condition loss and that results from inability of the bird or reduced ability of the bird, to digest material from its feed due to the damage to the intestine.

Death can result from round worm infection if the worm burden in the chicken is big enough to block the intestine. This is not so common but we need to be aware of this.

The control of round worms in poultry focuses on the use of insecticides and I’d most commonly use an in-water insecticide such as Nilverm which is a lavamizole product. However, we also need to consider the environment in an integrated approach to parasite management with respect to round worms.

And that, that is considering how the birds become affected with the worm. When we worm, we ideally should clean or turn the litter in the sheds if they’re housed inside, which will reduce the burden on the bird.

In range situations, it can be a bit harder, because it’s hard to manage the litter, thus it’s hard to manage the contact of the birds with the eggs, which is in the faeces, so if we can rotate ranges, so that birds are moving on to fresh pastures all the time, that will reduce the burden on the birds and also reduces our need to rely on insecticides or paracidocides to kill the worms.

Similarly, coccidiosis needs to be considered in an integrated approach to control. So coccidiosis is caused by a microscopic protozoan parasite meaning it can’t be seen by the naked eye.

The protozoan enters the bird, matures and replicates in the intestine similar to the round worm and is secreted in the faeces. So the damage caused in the intestine is an enteritis, an inflammation of the intestine, and we can see bloody diarrhoea and rapid loses of condition from infection with coccidiosis in poultry.

Birds most susceptible to coccidiosis are young, probably within their first one to two months, months of age.

We very much need to consider the environment in our approach to control of coccidiosis in poultry. Shed design which minimizes the chances of litter becoming wet, is hugely important in preventing this disease.

In the event of an outbreak of coccidiosis I recommend removal of all litter from the shed and replacement with fresh litter, to reduce the burden of parasite on the animal.

We should at all times try and limit our use of veterinary medicines in the absence of environmental control of the organisms to prolong the effectiveness of these agents.

Additionally, in relation to coccidiosis, we find that in commercially formulated feeds for young poultry, they often contain a coccidiostat.

This is different to a coccidiocide, in that it doesn’t kill the coccidiosis parasites, rather it, it slows their growth. And this is important in long term control of that parasite.

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Dr Brendan Sharpe

So poultry are a naturally active and inquisitive animal so a healthy, a healthy chook should be very active, and should be very aware of its surrounds, you and the other chooks and it should be interested in such.

So if we start with the head of a healthy chook, in the majority of breeds, the healthy chook has a bright red comb, face and wattles. Fowl pox lesions would cause abnormalities on the head, face and wattles of the chook and these present as raised, brown to black lesions and indicate infection with the fowl pox which can be spread by mosquitoes.

Moving down the chook, feathers of fowls or chooks should be tight, and shiny and free from any breaks or missing feathers.

So the healthy chook is a complete chook. It’s feathered all over and presents shiny. Absence of feathers or broken feathers anywhere on the body can indicate the presence of feather pecking in that flock of chooks and problems that cause feather pecking generally relate to stocking densities or having chooks too crowded.

The legs of poultry are naturally scaled and the bone is round, so the healthy chook should have a closely scaled, round leg that is shiny.

The most common problem we see with the scales of poultry is when they get infected with the scaly leg mite and what that does is cause a roughness to the scale, so it loses that smooth round appearance and smooth texture.

So a healthy bird, when you are handling it should have round muscles on the breast, and the keel bone, which is the sternum of the chook, should not be sharp to the hand when holding the bird. That indicates good muscling of the fowl and indicates adequate nutrition, general health and freedom from disease.

The beak on a healthy chook, the top beak should sit smoothly over the bottom beak. If the top beak overgrows the bottom beak too far, sometimes it needs to be trimmed.

When we talk about external parasites of poultry, the most common would be lice and mites. The lice and the mites are spread by the access of the poultry to wild birds so that’s an important consideration in shed design.

So lice is commonly seen as a small, brown and rapidly moving creature, most commonly seen on the vent of the fowl and you’ll also see clumps of white eggs that the lice leave on the poultry. So the lice live on, on the fowls 100 per cent of the time and they feed on blood and skin from the fowl.

The poultry will lose condition from irritation from infestation with lice, so when we’re considering the control of lice firstly if we can restrict the access of the birds or the poultry to wild birds that’s going to remove a great deal of the lice from the environment.

However, the application of insecticides, whether that be in a spray or in a dust formulation to the poultry and to their shedding will reduce the incidence of the lice.

Red mite are different from lice because they do not live on the poultry 100 per cent of the time. They actually reside in the shed. They like to live in cracks in wood and we particularly find that they live in cracks in the wood on the poultry shed perches. What they do is they leave their environment at night time and feed on the poultry.

This causes intense irritation to the fowls but what it does also causes a great deal of blood loss and anaemia and we can actually have deaths in poultry from blood loss from red mite. The most common sign you will see is paleness to the head from red mite infestation and if you pick the birds up you will actually find scars around the vent of the fowl which is where the red mites feed.

Red mite, again, are transmitted by wild birds so we’ve got to consider our shed design or range design when we’re considering how birds are becoming infected or infested with the red mite and thus how we control it.

Insecticides are very effective against red mite and should be applied to both the birds, but more importantly, the shed. So we need to ensure that we spray all wooden surfaces, litter and nest boxes in the shed to kill the red mite.

Northern mite differ to red mite because they, like lice, spend most of their life on the fowl. The northern mite, similar to red mite cause severe anaemia in the fowl but also severe irritation. They’re controlled similarly to red mite by the application of insecticides to the poultry but also to the poultry environment.

The easiest way in a school situation to do this is to actually get a liquid insecticide, make this up into a garden pump pack sprayer and this allows the sheds and the birds to be sprayed at once. I think it’s more effective and it’s simpler.

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Dr Brendan Sharpe

If you do find a sick bird in your school flock, the first thing that should be done is to isolate that bird.

Many of the diseases that we’re confronted with in poultry flocks are infectious, so by isolating the bird, you’re reducing the exposure of other birds in your flock to whatever the infection may be.

Once the bird is isolated, veterinary attention should be sought for an appropriate strategy. And with that advice, mitigation strategies can be put in place to prevent this from happening, and for preventing other birds from becoming ill.

The three main diseases that I’d advise all school-kept birds to be vaccinated against are Marek’s disease, Infectious Laryngotracheitis (or ILT), and Fowl Pox.

All three diseases are caused by viruses, and all are highly infectious.

If birds are, are bought at point of lay, most hatcheries will have vaccinated for all three at this point in time. And the vaccination of birds, and the sourcing of birds should be considered closely.

Vaccine handling is often quite difficult, and the sourcing of vaccines is often quite difficult.

Thus it is often easier to buy birds at point of lay from hatcheries that vaccinate.

So Marek’s vaccine is tended to give at hatch. So once they come out of the incubator, and ILT and Fowl pox vaccine are given later in life, generally at 3 to 4 weeks of age.

By ensuring our birds are vaccinated against these 3 diseases, we’ll prevent the occurrence of these diseases, but we also have a responsibility to the commercial industries in ensuring that the presence of these diseases is restricted as much as possible.

Generally with poultry health, prevention is better than treatment.

So by careful consideration of poultry husbandry, our facilities, our feeding practices, our vaccination practices, we can understand each disease, know how to prevent it, which much reduces the need to have to rely on expensive treatments.

By ensuring that all these practices are up to standard, we can have a healthy flock which is to the enjoyment and benefit of all those associated.

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