Coccidiosis can affect a large range of animals including cattle and sheep however the disease is species-specific. This means that poultry cannot contract the disease from sheep or infect sheep. The disease does however affect all animals within the avian species, meaning that turkeys, ducks, geese, fowls and other animals with the species can infect and contract the disease from one another.

Coccidiosis is an intestinal disease, caused by a microscopic parasitic organism called a protozoa. The protozoa attaches to the intestinal lining of the bird, damaging the gut tissues causing bleeding. The protozoa also prevents the bird from absorbing nutrients resulting in diarrhoea and weight loss, creating an environment where bacteria can thrive. The disease is more common in young birds (under 6 months) who have not built up natural immunity but can occur in mature birds. Affected birds will have a pale comb, blood in their faeces, diarrhoea, appear hunched over with ruffled feathers and will not eat.

The coccidiosis organism is carried by all poultry in their bowels however only some individuals will contract the disease. The cycle of the disease begins with an unsporulated oocsyt (a non-infectious stage of the organism) passing through a bird’s droppings. This unsporulated occyst can lay dormant in the soil for up to a year and will not sporulate until the environment around it is ideal. The occyst requires wet, humid conditions to sporulate and only upon sporulation will it become infectious. The oocyst can become infectious in as little as 24 hrs in humid, wet conditions with a temperature of 25-30°C. Examples of environments that may encourage sporulation are around waterers and feeders. The occyst has a thick protective wall around it which can protect it from heat, cold and disinfectants, making the parasite hard to destroy in the environment.

Poultry can easily ingest the sporulated oocyst through contaminated water and food and from the ground. Once digested, the bird’s stomach will break down the outer layer of the oocyst, allowing the oocyst to hatch and invade the cell lining of the small intestine. As the parasite goes through its life cycle, it will multiply inside the bird and continue to damage more cells within the gut lining. The parasite will also have a negative effect on the natural balance of bacteria within the bird’s gut, leaving the animal susceptible to harmful bacteria. The parasite will then be passed through in the bird’s dropping, allowing the coccidia oocyst to be ingested by other birds.

Coccidiosis is extremely easy to spread, the occyst can be spread on shoes, shovels, contaminated food, water and faeces. There are many different strains of the coccidiosis disease, making it particularly hard to vaccinate against. Healthy birds will build up an immunity to coccidiosis if they are exposed to low levels of it over time however birds will only develop immunity for the particular strain that they have been exposed to. This means that birds who have built up an immunity for one strain of coccidiosis, will be susceptible to different strains. Vaccinated birds will also only be protected against the particular strain that they were vaccinated for. These factors make it extremely easy for the disease to spread via contaminated food, soil, water, equipment and the introduction of new birds to an existing flock.

Coccidiosis can be fatal for poultry if not treated however early diagnosis and treatment is often successful.

Diagnosis

Early diagnosis is crucial if treatment is to be successful. Poultry health can typically deteriorate very rapidly, making regular monitoring of birds extremely important at all times. Coccidiosis can develop rapidly with an incubation period of 8 days and symptoms can develop both rapidly and gradually. Symptoms of coccidiosis can easily be confused with symptoms of other diseases. For this reason it is important to seek veterinary advice when diagnosing. The most common symptom of the disease is blood in faeces however this is not always a symptom and can be a symptom of other diseases.

Symptoms of coccidiosis include:

• Blood in faeces
• Mucous in faeces
• Hunched over appearance
• Ruffled feathers
• Weak , listless and not active
• Huddling together
• Pale comb and skin
• Loss of appetite
• Weight loss
• Failure to grow
• Inconsistent egg laying or no egg laying
• Diarrhoea.

Treatment

Prevention is always better than treatment however if treatment is necessary, the quicker treatment commences, the higher the chance of a successful recovery.

If a bird is diagnosed with coccidiosis, the entire flock must be treated to successfully eradicate the disease. The first stage of treatment is to isolate the sick bird/s to a clean, dry, warm enclosure. Treatment should begin immediately and the affected bird/s should be kept in isolation until its symptoms have disappeared. Once the bird has recovered and the rest of the flock has been treated, the bird can be returned to the flock.

A commercial treatment will be required to stop the parasite from multiplying and attacking the bird. Amprolium is a commonly used treatment that can be added to the bird’s water supply however birds with coccidiosis are typically off their food and water. The treatment may need to be individually administered to affected birds via a small syringe to ensure they receive the correct dosage. If the remaining flock appear healthy and are drinking normally, treatment can be administered via their water supply. Amprolium is not a prescription medication however it is highly recommended that in the case of a coccidiosis outbreak, professional veterinary advice is sought to discuss the most effective way of medicating the flock and avoiding future outbreaks. Treatment is usually recommended for 7 days however a veterinarian will be able to advise a treatment plan.

Prior to administering treatment in the water supply, it is essential that water containers are thoroughly cleaned and that the enclosure is clean, bedding is dry and waste and damp areas around water and feed is removed. This will help to remove the parasite's environment and prevent further outbreaks.

Prevention

Prevention is always better than a cure as treatments can be costly, time consuming and not always successful. There are a number of methods that can be used to prevent coccidiosis in the flock.

Hygiene

Hygiene is the most simple, yet most important method of controlling coccidiosis. The parasite requires a warm, damp, humid area to be able to become infectious so it is important that any areas of the bird’s enclosure that could provide this environment are removed. Damp areas around waterers, feeders and unclean nest boxes can easily provide an environment for the parasite. Enclosures should be cleaned thoroughly, very regularly with any damp or dirty bedding being removed. If the enclosure has an outdoor soil area, this should be kept as dry as possible with a roof and good drainage. Sand can be added to soil to increase drainage. Areas around feeders and waterers should be kept particularly clean and dry as this is the most likely area for a bird to pick up an occyst and ingest it. Placing feeders and waterers on concrete is recommended as this prevents the surrounding area becoming damp and allows for easy cleaning.

Waterers and feeders should also be cleaned out regularly and water should be kept clean and fresh.

Feeding

Feeders should be kept clean and slightly raised from the ground, and on concrete if possible. Ensure that there is an adequate number of feeders to avoid a large number of birds swarming around feeders. Any spilt food should be removed daily and feed should not be fed out on the ground where it can be contaminated.

Quarantine/enclosures

There are many strains of coccidiosis and it is possible for different flocks of birds in different areas/enclosures to be exposed to different strains of the disease and therefore have built up natural immunity for that particular strain. For this reason it is important to ensure birds stay in their assigned enclosures and that if any birds need to be moved, they are quarantined for a period of time. It is also very important to quarantine any new birds that have been purchased from another property before introducing them to the flock. The recommended quarantine period for birds being introduced to the flock is 2 weeks.

In the case of free range birds, ensure they cannot stray onto neighbouring properties where they could potentially become infected with a strain that they are not immune to.

Space

Refer to the Animals in schools space requirements for Poultry – Fowls and ensure that birds have adequate space. Overcrowding can increase the chance of coccidiosis as there will be an increased amount of faeces and more birds surrounding waterers and feeders and typically making it more difficult to keep the enclosure clean and dry.

Medication/Vaccination

Medicated starter feed for chicks is available to protect chickens against coccidiosis. This is a recommended strategy when purchasing or raising young chickens however it is important to know if purchased day old chickens have been vaccinated against coccidiosis and which strain of coccidiosis they have been vaccinated against. Chickens that have been vaccinated should not be fed the medicated starter feed.

Due to their short life span, it may be unnecessary to give medicated feed to broiler chicks considering the need to have a withholding period. A better option may be to observe strict biosecurity techniques and manage the environment.