Broiler coccidiosis: symptoms, prevention and treatment records
Coccidiosis caused by Eimeria protozoa is one of the most common parasitic diseases in broiler production. Learn how to recognise it, how to prevent it, and how to keep compliant treatment records.
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What is coccidiosis in poultry?
Coccidiosis is a parasitic disease caused by protozoa of the genus Eimeria. In broilers, the most clinically significant species are Eimeria tenella (caeca), Eimeria acervulina, Eimeria maxima and Eimeria brunetti (small and large intestine). The parasites destroy the intestinal epithelium, impair nutrient absorption and — in severe cases — cause haemorrhage into the intestinal lumen. The disease spreads via the faecal-oral route: oocysts shed by infected birds contaminate litter and are ingested by healthy birds.
What are the symptoms of coccidiosis in broilers?
First signs usually appear between weeks 2 and 6 of life. Key symptoms include: watery or bloody diarrhoea (blood in faeces is an alarm signal pointing to Eimeria tenella), wet litter beneath feeders or on the floor, lethargy and birds huddling under heaters, reduced appetite and water intake. As a result, body-weight gain deteriorates markedly and the Feed Conversion Ratio (FCR — kg of feed per kg of gain) worsens. In mild cases the disease is subclinical: the only signal is poorer production performance without visible diarrhoea.
Why is coccidiosis dangerous for production results?
Eimeria damage to the intestinal epithelium means the bird cannot efficiently absorb protein, energy or vitamins — even on a full ration. Every 1% FCR deterioration translates into measurable cost for the farmer. In severe outbreaks there is high mortality, the need for early slaughter and losses from flock non-uniformity. An additional risk is that impaired gut mucosal immunity opens the door to secondary bacterial infections — notably Clostridium perfringens, which causes necrotic enteritis (NE).
How does litter quality affect coccidiosis risk?
Litter moisture is a key risk factor. Eimeria oocysts sporulate (become infective) within 1–3 days in warm, wet conditions. Excessive litter moisture — from leaking drinkers, poor ventilation or diarrhoea of another cause — dramatically accelerates parasite multiplication. More on litter management: Poultry house litter — management.
Coccidiosis and other poultry diseases
Coccidiosis often occurs alongside other diseases or acts as a predisposing factor. Intestinal damage creates conditions for Clostridium colonisation and necrotic enteritis. Whenever coccidiosis is suspected or production results deteriorate, consult a veterinarian and arrange diagnostic testing. Overview of other diseases: Poultry diseases — symptom table.
How coccidiosis affects the flock and production results
Each of these signals should prompt the farmer to consult a veterinarian.
Bloody or watery diarrhoea
Blood in faeces — especially dark red — indicates caecal damage by Eimeria tenella. This signal requires immediate veterinary intervention.
Wet, caked litter
Excessive litter moisture is the first environmental signal of coccidiosis. Oocysts sporulate in warm, wet litter within 1–3 days.
Lethargy and huddling
Sick birds stand fluffed up, avoid feeders and huddle under heaters. Observing flock behaviour allows early detection of the problem.
Worsening FCR
Damaged intestinal epithelium cannot absorb feed efficiently — a rising FCR with unchanged feeding is an early signal of subclinical coccidiosis.
Poorer daily weight gain
Slower growth and flock non-uniformity (large weight differences between birds) may indicate coccidiosis that has been running for several days.
Deaths and mortality spikes
In severe cases, especially when coccidiosis co-exists with bacterial infection, mortality can rise sharply in a short time.
How to prevent coccidiosis and how to act when disease is suspected
Effective prevention combines three elements: medicated feed, vaccination and environmental management.
Coccidiostats in feed
Chemical coccidiostats (ionophores and non-ionophores) added to starter and grower feeds inhibit Eimeria development in the bird's intestine. Their use is legal in the EU and regulated by animal nutrition law — always based on veterinary guidance and with the withdrawal period before slaughter strictly observed.
Coccidiosis vaccination
Vaccines contain live attenuated or field-strain Eimeria oocysts administered to birds in early life via drinking water or spray. They allow natural immunity to develop without severe clinical disease. Ionophore coccidiostats are not used alongside vaccinated programmes.
Litter and moisture management
Keeping litter dry and friable limits oocyst sporulation. Key actions are checking drinker performance (leaking nipples), adequate house ventilation and, where needed, partial litter replacement. Details: Poultry house litter.
Diagnostics and the vet's role
Coccidiosis diagnosis is based on clinical signs, post-mortem findings in dead birds and faecal examination for oocysts (flotation or McMaster). Treatment — drug selection, dose, duration — is determined exclusively by a veterinarian.
Treatment records and withdrawal
Every administration of a veterinary medicine (including a coccidiostat outside the starter feed) must be recorded: date, drug, dose, route of administration, withdrawal period. DlaFerm.pl allows these records to be kept digitally. More: Treatment records and drug withdrawal.
Production monitoring in the Flock Card
Tracking FCR and daily weight gain in the Flock Card enables subclinical coccidiosis to be detected before clear clinical signs appear. Early response limits production losses.
Frequently asked questions about coccidiosis in broilers
What is coccidiosis in broilers?add
Coccidiosis is a parasitic disease caused by Eimeria protozoa that destroy the intestinal epithelium. In broilers it causes diarrhoea (sometimes bloody), lethargy, worse FCR and growth, and increased mortality. It spreads through oocysts in the litter.
What do faeces look like in coccidiosis?add
With Eimeria tenella infection, faeces contain fresh or dark-red blood (caecal damage). Other Eimeria species cause watery, mucoid diarrhoea without obvious blood. Any change in faecal consistency or colour should prompt a veterinary consultation.
Are coccidiostats enough to protect the flock?add
Coccidiostats effectively reduce risk but do not eliminate Eimeria completely. Prolonged use of the same substances can lead to resistance. Feed producers therefore rotate active substances, and many farms are moving to vaccination programmes. The final decision on the prevention programme rests with the attending veterinarian.
When are coccidiosis vaccines used?add
Vaccines are used mainly in breeder and layer flocks and increasingly in broiler farms running antibiotic-free or ionophore-free programmes. Vaccination takes place in early life. The choice of programme is made by the flock veterinarian.
What should I do if I suspect coccidiosis in my flock?add
Contact a veterinarian. Do not administer drugs without a diagnosis and prescription — some products have a withdrawal period before slaughter, and incorrect use can expose the farmer to legal consequences. The vet will order diagnostic tests and prescribe treatment.
How does DlaFerm.pl help with coccidiosis?add
DlaFerm.pl enables digital treatment and withdrawal records — legally required documentation for every administration of a veterinary product. The Flock Card lets you track FCR and daily weight gain, making early detection of subclinical coccidiosis easier. Data are always available for veterinary or inspection visits.
Sources & resources
- linkNational Veterinary Research Institute — PIWet (Puławy)
- linkEFSA — scientific opinion on coccidiostats and histomonastats
- linkChief Veterinary Inspectorate Poland — information for poultry farmers
- linkKRD-IG — Polish Poultry Council Industry Chamber
- linkRegulation (EC) No 1831/2003 on additives for use in animal nutrition
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