Understanding Coccidiosis


Most believe Coccidiosis to be host specific meaning that the Cocci that cattle get can not infect chickens, turkeys, geese, dogs, or any other animal. It will only make cattle sick. And the Coccidia that chickens get will only affect chickens and no other animal.

It is believed all animals carry Coccidiosis that is specific to there species only.

Coccidia is a pathogen, a parasitic egg, making it a species in itself which by definition can be transmitted via infected faeces
to another animal.
It has been reported/alleged that other species have died from chicken specific Coccidiosis, although no definitive proof has ever been forthcoming.
It is also reported/alleged recently that a dog died of 'chicken specific' Coccidiosis after eating an infected carcass.
There was never any pathology to support the alleged causes of death.
However it is recommended that you do not allow any of your meat eating pets to ingest any part of a known infected bird.

Infections of Coccidiosis of chickens =

Infestations enter the bird via infected faeces.

Most Oocysts take four to seven days on average to complete their cycle, others two days if conditions are right..

Chickens will eat the Oocyst and in favourable conditions = heat, humidity and moisture on the ground, the Oocyst sporulate
and become infective. When testing for Coccidiosis in any animal several faecal floats are done.
You will not always see Oocysts on the first float, hence 3 or more are done.

Chickens are not always shedding the Oocysts. Healthy, and sick, livestock carry Oocysts. The only difference being that the healthy livestock have an immunity to the Coccidia, and the sick have either not had the opportunity to build up the immunity needed or there are too many stress factors in their life for their system to cope.

In test floats the Oocysts will either be sporulated or unsporulated = the difference between healthy and sick birds.

When Oocysts sporulate cell division inside the Oocyst happens. The outer lining of the Oocyst  ruptures and releases its contents into the faeces which is then eaten by another bird, passing into its intestine. The bird gets sick.

A simple way to explain sporulation is to imagine a clear egg with two linings, an inner and an outer lining, as per picture above
In that egg you have four smaller eggs (sporocyst) and in those eggs are two even smaller eggs (sporozoites).

The infected Oocyst cycle has already commenced in the ground - when eaten by the bird the sporozoites escape from the Oocyst or clear egg with two linings and the sporozoites multiply many times.

There may be several generations of asexual multiplications but it is self limiting and will stop.

Then the sexual stage happens in which the male and female cells join and form new Oocysts =
these are once again protected by the two linings on their outer shell.

This starts on the ground. This is when the infected Oocyst is eaten.
This is when the cycle will continue and other birds get sick.

If the Oocyst dose not sporulate they will co exist without major problems.
In a stressed bird after sporulation happens the bird gets sick and you will notice a number of different signs.

Infected birds could be standing in the corner on their own slightly fluffed up, or you may find the bird dead with no warning.

The most common sign is watery, runny, bloody droppings.

Stress factors can be many and varied = anything the chickens are not used to.

You need to isolate the sick bird from the rest.

Treat all birds with Baycox, or Amprolium or your choice of Coccidiocides which kills the protozoa.

Follow the instructions on the bottle/container, as well as your Avian Specialist Vet.

The sick bird that has bloody watery droppings needs special attention.
It is going to need a heat source to keep it warm and probably antibiotics to prevent secondary infections like pneumonia.

It is not always the Coccidia that kills the bird; it could be a secondary infection contracted due to being unwell with Coccidiosis.

This sick bird is also going to need extra fluids to help it = Electrolytes are crucial.
Electrolytes will help to rest the gut and intestines, and will give the extra energy needed while the bird is sick.

A quiet room, a carry cage or cardboard box with soft bedding/wood shavings and a hot water bottle well wrapped so
it does not burn the bird are ideal.

Only use Baycox when needed. Don’t just give it to you birds because you think they might have Cocci.


Once all this is done stand in front of a mirror and look at yourself. Have a good long hard look.

Ask yourself this question = “Why did my birds get Coccidiosis?”

Just in case you don’t know I will share the secret with you.

I am being blunt here.

It is your fault. You caused it in some way.

You may either have your birds overcrowded, or perhaps you haven’t cleaned the pen for a while, or is it that leaking roof or maybe that drafty housing and they couldn’t get out of the draft. Or even that muddy ground around the water dish.
Maybe you brought in from someones yard on your shoes, or you haven't controlled the vermin and they carried it in.

Until you do everything that is in your power for your birds, illness will continue to happen.

In most cases you will have done something to cause illness in your birds.
Transporting birds can cause Coccidiosis. Remember they always carry it and if the birds have had poor nutrition and being penned to be transported and have an out break of Coccidiosis. You can’t blame the person on the other end entirely for them having Coccidiosis when you get the birds.
Yes if Baycox was given it would have helped, but the travel stress was the main contributing factor with the bird/s getting sick.

I am sure you understand what I am saying.

The best way to control Coccidiosis is Good Husbandry Technique’s.

Young birds being kept in clean dry housing.

Good feeding practices, let your chickens build up a natural immunity over time by feeding medicated feed.

The Coccidiostat found in feed has a depressant effect on the early, (first stage) of the Schizonts and this is how it is used to control. Alternately use Amprolium or vaccination.

Good management and good sanitation by cleaning all food and water dishes of faeces regularly is essential.

Also control of vermin, they can also spread the chicken Coccidia on their feet and fur.


There are eleven species of Coccidia in chickens, these are a few of the worst ones:-


Eimera acervulina, Eimeria maxima –

Both these species develop in the tissue that protects the organs in the upper part of the small intestine.


Eimeria tenella (most destructive of all) -

This one develops in the cells of the cecca which are two blind sacs near the end of the intestine. It is one of the most infective.


Eimeria necatrix -

Develops in the small intestine in the early stage and later in the cecum at the sexual stage. Like E. tenella it develops in the deeper tissue of the small intestine.


Eimeria mitis, Eimeria brunetti, Eimeria praeco -
The Coccidiosis Oocyst are resistant in the environment, climate extremes and disinfectants and will survive in the soil for weeks unsporulated and more than 600 days once sporulated if protected from the extremes. 

But it will only survive in deep litter for a few days due to heat caused by ammonia and fermentation.

Oocysts are destroyed by below freezing and extremely high temperatures.

I hope this helps to understand the pathogen.



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