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Posted by Phil Weymouth
Created 20th November 2010 Chickens & Ducks

Coccidiosis in Chickens

Coccidiosis, A Beginner's Guide ...

Poorly hen

Most of us keeping a few hens will enjoy a lifetime of blissful feathered friendship without ever coming across the lurking nasties that can afflict even the fittest of fowl.

But forewarned is forearmed ...

Coccidiosis, pronounced cock-sid-ee-oh-sis, is a disease caused by a coccidial oocyst (pronounced oost) the most common of which is 'Eimeria tenella'. 

In simple terms a microscopic parasite (a coccidia) is ingested by the bird, it attaches itself to the lining of the gut, multiplies and becomes an oocyst feeding in the digestive tract of the bird and consequently will make it bleed. Once infected, the bird will be passing these parasites in its poo days before symptoms occur. The most common tell-tale sign, from the most common type of coccidia, is blood in the poo because the parasite makes the gut lining bleed.

There are many types of coccidia but one type will only infect one type of animal i.e a poultry coccidia will not infect a calf or lamb and vice versa. However, treating and curing one type of poultry coccidia does not mean that they cannot be later infected by another type.

The oocyst eggs are passed out through the droppings and this is how it infects other birds. Adult birds can live perfectly well with small infections their whole lives and if you use a preventative tonic like Apple Cider Vinegar & Garlic this can certainly keep on top of any oocysts and other worms. This 'acid' in the gut will help to prevent the formation of the oocyst which does the damage.

However, when egg production drops, there is blood in the poo, the bird is lethargic and generally looking unwell then another treatment is needed. If not treated quickly at this point the bird may die.

Quote from government DEFRA document about coccidiosis in poultry:
Coccidiosis caused by E. tenella first becomes noticeable at about three days after infection. Chickens droop, stop feeding, huddle together, and by the fourth day, blood begins to appear in the droppings. The greatest amount of blood appears by day five or six, and by the eighth or ninth day, the bird is either dead or on the way to recovery. Mortality is highest between the fourth and sixth days. Death may occur unexpectedly, owing to excessive blood loss. 

Symptoms and Causes


  • Passing blood in their poo.
  • Drop in egg production.
  • Droopy, hunched, withdrawn chickens with ruffled feathers.
  • Not feeding or drinking.

Causes of infection:

  • Coccidiosis is caused by a parasite (coccidia) found in contaminated ground and damp bedding. It can be transferred on contaminated boots, feedsacks, insects and rodents.
  • Poultry are exposed to the parasite via their droppings, dirty drinkers and damp litter in their housing. Wet areas around drinkers are particular areas of infection. 
  • Coccidia can also be found in water that is not kept clean and free of chicken droppings. 
  • Young birds and chicks (of all kinds) are most prone to infection and will quickly die if not treated.
  • Overcrowding and intensive rearing of chickens leads to infection passing quickly throughout the flock.
  • Infectious parasites can live in housing that was previously contaminated for a number of months and so will infect new birds when they are introduced.

Cure and Prevention

Lemon Pyle Brahma Cockerel

The Cure:

Coxoid* liquid is a Coccidiosis Treatment for pigeons that is widely used for poultry, although not technically licensed for poultry it can be used when advised to do so by Vet or licensed supplier. Egg withdrawal periods (i.e. eggs must not be eaten) are normally needed with treatments such as this and then followed up with a poultry tonic e.g. Lifeguard Poultry Tonic. Coxoid* is administered in their drinking water for seven days, the egg withdrawal period may be up to 28 days or as advised.

Clean their house, run (and the ground they live on), and all utensils with Bi-OO-Cyst Coccidial Disinfectant which will kill all coccidial parasites.

For the ground we recommend Stalosan F Powder or Net-tex Ground Sanitising Powder which dries up the area where they live and prevent the dampness that oocysts thrive in. Regular use of a sanitising powder will prevent any further infections. Parasites can live in empty houses, and the ground, for several months.


Vaccination at the earliest age, usually day-old. One commercial vaccine has a brand name of Paracox. If buying birds from a breeder ask if they have been vaccinated or fed on a feed containing a coccidiostat. If buying from an auction - beware!

During growing stages, feed the birds with a feed containing a coccidiostat so that they have built immunity by the time they reach adulthood. This type of feed is prevention, not a cure, and there are differences of opinion as to its effectiveness.

If hatching eggs yourself, treat with Coxoid* in their early days, or keep the chicks on a wire floor so they do not stand in their own poo. Birds under three weeks old are seldom infected.

Keep litter dry when housed indoors, particularly with young birds. Clean brooders every day and do not allow birds to walk around in their own poo. If possible, put drinkers on a wiremesh stand so that the birds do not stand in wet bedding.

For adult birds housed outdoors - keep the bedding in the house clean and dry. do not put drinkers and feeders inside the house unless absolutely necessary (damp contaminated litter is one of the greatest causes of infection). Unless the birds live indoors on a semi-permanent basis, they will only use the house to lay eggs and sleep at night. They do not feed or drink once they have gone to bed.

If birds are housed indoors then consider a watering system that will not allow contamination from poo or debris, and that will not spill and make the bedding damp. e.g. Maxi-Cup Poultry Drinker or for outdoors, a large Honeypot Tripod Poultry Drinker.

Outdoor birds need clean ground, their run will need moving regularly so that the ground does not become 'poisoned' (fowl sick). If this is not possible, then a regular cleaning of the ground in the run is necessary to prevent infections. Use Stalosan Disinfectant Powder or Bi-OO-Cyst Coccidial Disinfectant (links above). Bi-OO-Cyst is specially formulated to kill coccidial occysts. Oocysts can otherwise be killed by freezing, extreme dryness and high temperatures

Vigilance is necessary to watch for tell-tale signs. Coccidiosis is most common in young birds over three weeks and their first year or so. Older mature birds are likely to have built up some immunity.

In short, keep the house bedding dry and clean, do not allow contamination of drinking water, and wash drinkers and feeders regularly in disinfectant. Keep the ground in their run clean, dry and disinfect regularly. 

I hope you have found this helpful. If you have any questions though please feel free to just email me:

(Image above: our beautiful Lemon Pyle Brahma Cockerel - Sir Walter)


Coccidiosis, a Beginners Guide is ©Flyte so Fancy 2010. Author: Anne Weymouth. Reproduction of part or all of this text is only possible with the express permission of Flyte so Fancy.

* Coxoid is not licenced for use on poultry because it has not been tested on poultry regarding a meat withdrawal period, although it does have a 28 day egg withdrawal. We cannot therefore advise on its use for poultry as we are not qualified to do this and to do so would breach VMD rules. We strongly advise consulting a vet before use.

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