The Complete Chicken Parasite Guide 

Worms, mites, lice and other parasites cause stress, illness and underperformance in chickens. Backyard chicken keepers should be aware of the symptoms of these common parasites and have a management plan in place for the prevention and treatment of parasites in the flock.

Chicken parasites are divided into two categories, internal and external. Internal parasites, such as worms and coccidia, live in a chicken's body and are usually spread through excrement in the feed and water supply. This type of parasite can drain your hens of needful vitamins and minerals, leading to a variety of deficiencies and digestive problems. External parasites live on chickens or in the coop, and include mites, lice and fleas. Mites will feed on the chicken's blood, whereas lice will feed on skin follicles. Some mites live on chickens, while others live in the coop.

Prevention of Worms, Mites and Lice in Poultry

You will quickly learn that prevention of parasites is not only an easier road than treatment, but you will also be rewarded with happier hens! 

For external parasites such as lice and mites, it is essential for you to keep a clean chicken coop and hen house. Regular, preventative treatment for lice and mites is recommended in some environments, just the way we treat dogs and cats for fleas. Dust bathing is an important natural behaviour that chickens use to manage external parasites.

To naturally prevent internal parasites such as roundworms and gapeworms, try to ensure that your birds cannot leave their droppings in their feed or water. You can do this by choosing a feeder and drinker that they cannot stand or scratch in. 

Other natural preventative measures include ensuring a clean hen house with dry bedding and keeping a relatively stress free environment. Adding Apple Cider Vinegar to drinking water, and preventing contact with wild birds and rodents will also help.

External Chicken Parasites - Mites and Lice

These parasites live outside of chickens. Some of them live on the birds themselves, while others live in the coop or environment. Most chicken external parasites cause irritation and ill health in your birds by feeding on their blood.

Northern Fowl Mite

The northern fowl mite is a poultry parasite that lives on chickens. It is the most common external chicken parasite in the USA.

This mite is tiny in size and not easy to spot at first sight. At its largest, its body is 1mm in length. They are found on a chicken's feathers and body, feeding on their blood, potentially up to 6% of a chicken's blood total. Mites are easily transferred from hen to hen and can be introduced to the coop by rodents, wildlife and birds.

Northern fowl mites typically infest the vent area. They can feed at any time of day. Be aware of the symptoms and provide the necessary treatment for this parasite.

Signs & Symptoms:

• Typically, poultry with an infestation will have black debris, a build up of mites and their excrement, clumped around their vent area
• Chickens may display irritation, itching or pain at the affected site
• Decreased egg production
• Weight loss and poor appetite
• Anaemia (iron deficiency), often recognisable by a pale comb

Treatment:

It is equally important to not only treat the northern fowl mites and also put in preventative measures.

We recommend treating infected birds with a commercial mite treatment. It is also important to treat the coop and nesting boxes. Treat all chickens in the flock, even if only a few appear to have mites. Re-treat again after 2 weeks.

Diatomaceous Earth can be used in the chicken coop to prevent mites. It can also be added to dust baths, and some chicken keepers recommend putting it directly on chickens to kill mites. Avoid inhalation.

Chicken Red Mite

The chicken red mite, also simply called chicken mites, are another common chicken mite. As these mites measure as little as 0.6mm-1mm, they can be difficult to eradicate. In fact, it may even take a while to recognise an infestation.

Although you can find red mites on your chickens in the case of a severe infestation, these mites don't actually live on the bird. Instead, red mites live in the cracks and crevices of a chicken coop. At night time, they will come out of their hiding places to feast on your backyard chickens' blood.

This creates a traumatic environment for your chickens. You may see their health deteriorate with an increased risk of anaemia and odd behaviours as red mites terrorise your hens at night.

Signs & Symptoms:

• Reduction in weight gain in young birds
• Reduced egg production
• Pale comb due to anaemia
• Chickens are avoiding roosting in the coop at night
• Chickens are not laying in the nesting boxes
• Restlessness in the flock at night
• When checking the coop, you may notice clumps of red mites or of their excrement.

The best way to identify a red mite infestation is to check the chicken coop for mites after dark. Take a torch and look for tiny red mites on the walls, beams and roosts. Or on your chickens!

If you find red mites on your chickens in the day time, you have a severe infestation that needs immediate treatment.

How to Control Red Mites

The most effective treatment for chicken red mites is a two-pronged approach: treating the chickens and the coop. It may take a few treatments to see total eradication.

Ideally, treat your chickens at night time when the mites will be on the feathers. Or treat your chickens just before they go in to roost, using a commercial mite treatment.

The next day, lock your chickens outdoors and treat the coop. This means cleaning out all bedding and droppings. You must also treat crevices, cracks and nesting boxes with the mite treatment, as this is where the mites will be hiding. If you are using a mite spray, you can also spray walls, roosts and other surfaces.

Re-treatment is recommended 2 weeks after the initial treatment. After the second treatment, judge if another re-treatment is required by checking the coop at night for signs of mites.

Regular preventative treatment is recommended for chicken keepers in warmer climates where mites are more active. Diatomaceous Earth is a natural option for preventing mites.

Scaly Leg Mites

Scaly leg mites are a chicken parasite that lives beneath the scales of the feet and legs. These tiny mites cause a lot of discomfort to chickens as they eat the tissue under their skin, depositing crud in its place. The result is a lumpy, crusty appearance on the feet and lower legs. Lesions will often be infected and irritated.

If left untreated, these mites can cause lameness, loss of toes and infections that may result in death.

It's important to note that scaly leg mites can also affect wild birds, which may bring the mite into the chicken run.

Signs & Symptoms:

• Crusty looking skin on feet and lower legs - may appear lumpy
• Thickened legs

Treatment

While it can be reasonably straightforward to rid your chicken of scaly leg mites, the effects and deformities that they cause on their feet and legs are lasting. Therefore you must apply treatment and re-treatment as soon as possible.

To treat scaly leg mites naturally, we recommend using VetRx solution or another commercial mite treatment. For VetRX, the procedure is easy. Simply soak the chicken's feet in a warm bath of water for 5-10 minutes, then softy rub the skin with a gentle toothbrush to remove any excess scales. When you have finished, dry the feet and generously apply VetRx remedy solution onto the feet, legs and comb if affected. Repeat this process every three days. Alternatively follow the instructions on your treatment of choice.

Remember to treat the hen house and coop using insecticide.

Lice: Shaft Louse

Lice are a nuisance problem for backyard chickens. Shaft lice are an ectoparasite that live and breed on your hens, causing irritation and inflammation, resulting in significant discomfort.

Measuring between 1mm - 6mm in size, lice are relatively easy to spot if you are looking for them. You will notice they move quickly in and around the feather shafts. These parasites live on chickens and don't survive long in the environment.

Signs and Symptoms:

• Lice eggs will be found in whitish clusters at the base of a feather; sometimes these will be easier to spot around the vent area
• Reduced egg production
• Scratching against posts or fencing
• Preening more than usual

Treatment of lice

Just like in humans, poultry lice can be difficult to treat - often taking many rounds of treatment for success. This is due to their egg cycle, which can be resistant to treatment.

To rid your chickens of lice, you should use a poultry dust or lice spray. Follow treatment instructions and ensure you are treating the feathers down to the shaft. As the lice eggs hatch, you will need to do another round of treatment.

Some chicken keepers use Diatomaceous Earth for lice treatment and prevention.

Internal Chicken Parasites

These parasites live inside a chicken. Although worms are the most common internal parasite that causes health problems in chickens, coccidia are also ubiquitous and can cause severe illness or death in certain circumstances. Most internal parasites live in the gut of the chicken, but there are also worms that infect the eye and throat.

Internal parasites generally live the adult stage of their life inside chickens. Chickens get worms from consuming worm eggs, which are found in the soil and in the faeces of infected birds. Some types of worms live part of their life inside an insect, such as a slug or earthworm, and infect chickens when they consume the insect.

Worms are most likely to effect free range chickens that consume a lot of insects and chickens that have contact with wild birds.

With intestinal worms, chickens can handle a small worm load without any ill-effects. However, severe worm infestations or worms combined with another illness or source of stress can make chickens very ill or even kill them. For this reason, even if your chickens do not have any symptoms of worms, it is recommended that you use a dewormer as a regular preventative.

Fortunately most poultry dewormers treat the most common poultry worm species, so preventative treatment will stop most problems.

Roundworms

Roundworms (Ascaridia spp.) are a fairly common parasite found in chickens and birds. Subspecies of roundworms include large roundworms and small roundworms. Large roundworms are particularly harmful to backyard chickens, causing intestinal blockages, malnutrition and even death.

Symptoms:

• Weight loss
• Eating more often or increased appetite
• Worms in chicken poo. If you look closely, you may see teeny tiny white strands in the chicken poo
• Pale yolk colour
• Decreased egg production
• Very rarely, a small hair-like worm can be seen in an egg - this is very rare, and not dangerous

Treatment:

To treat internal parasitic roundworms in chickens, use a chicken dewormer that is suitable for use in laying hens and ideally has no withholding period for eggs.

Tapeworm

Tapeworms are another common chicken parasite. In healthy, unstressed birds, tapeworms are unlikely to cause any symptoms or ill-health.

Treatment

Few of the most common worm treatments for chickens kill tapeworm. If your chickens have worms and a normal dewormer has not solved the problem, it may be tapeworms. See your vet for a faecal test and specialised worm medication.

Threadworm

Threadworms are also called hair worms. There are many different threadworms, or Capillaria species. Some live in the intestine, while others are further up the digestive tract.

Symptoms:

• Weight loss
• Pale combs
• Droopiness
• Decreased egg production
• Very rarely, death

Treatment

Treat threadworms in chickens with a poultry dewormer.

Cecal Worms

Chicken cecal worms are, as the name suggests, found in the ceca, which is a part of the digestive system joining onto the intestine. Cecal worms aren't generally a problem in themselves, but they can carry the blackhead parasite, Histomonaisis, which is fatal to turkeys.

Treatment

Many poultry wormers treat cecal worms.

Gapeworm

Chicken gapeworms are thin, red worms that reside in the chicken's trachea or throat. This is particularly harmful as an infestation can quickly move to the lungs and obstruct breathing or stop the chicken from eating. If your chicken appears to be coughing or clearing its throat, it may have gapeworm.

Signs and Symptoms

• Chicken is gasping for air
• It looks like your hen is yawning
• Shaking their head, trying to dislodge the worms

Treatment of Gapeworms

If one bird is showing signs of gapeworm it is important to treat your whole chicken flock. Not all dewormers treat gapeworm, so read the bottle carefully and always follow the instructions.

Protozoa - Coccidia

Coccidia are a form of protozoan parasite. Coccidia live and breed in the chicken's digestive tract, causing tissue damage and reducing the ability to absorb nutrients. Coccidiosis is the inflammation caused by coccidia. 

While all chickens carry coccidia, new strains can cause illness. Coccidiosis is also particularly severe, and often fatal, in young chickens because they are yet to develop immunity to the parasite. Birds that are stressed or otherwise unwell, or enter a new environment containing different strains of coccidia, are also at risk. New strains of coccidiosis can also be introduced to the flock by wild birds.

Signs & Symptoms

If you see any of the following symptoms in your backyard chickens, you need to act fast.

• Bloody or watery stools
• Lack of appetite
• Droopy posture and lethargy
• Reduced egg production
• Pale combs and wattles
• Death

Treatment of coccidiosis

The majority of chickens that come into contact with coccidia will have developed an immunity to this parasite. However, if you see the above digestive symptoms, it is important to seek early treatment so that your chickens should have a good prognosis. Without early treatment, coccidiosis can easily wipe out your entire flock.

Treatment involves quarantining symptomatic birds from the rest of the flock and administering a coccidiosis medication. Adding Apple Cider Vinegar to the drinking water of the flock can stop the further spread of coccidia. In some cases, treatment of the whole flock may be necessary. Consult with your veterinarian.

In Summary

Above we have discussed the most common chicken parasites. By having a firm health baseline for your chicken flock, you will be able to quickly determine if they are unwell, and treat early if necessary. Next time you are feeding your chooks, take note of their overall vitality, the colour of their combs, how much feed they are consuming and how their stool looks. 

Prevention is always better than a cure, so keep a clean coop and run, never feed your chickens on the ground and provide clean food and water. Deworming chickens regularly and treating for parasites is also recommended for many flocks.

Happy chicken keeping!

Rachael at Dine a Chook