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Coccidiosis

Other Names: Avian Coccidiosis

Coccidiosis is the clinical illness caused by infection with the protozoan parasite genus Eimeria (coccidia). The nine coccidia which infect chickens are E. acervulina, E. brunetti, E. hagani, E. maxima, E. mitis, E. mivati, E. necatric, E. praecox and E. tenella. Most of these parasites invade the chicken’s intestinal tract, but some invade other organs, such as the liver and kidney.

Chickens become infected by ingesting sporulated oocysts (coccidia "eggs") from the surrounding environment. When chickens are exposed to Eimeria early on, as long as there are not excessive levels present in the environment, they will usually develop a natural immunity, without any treatment necessary. However, if their immune system is lowered due to infection with another disease, stress, or exposure to a new species of Eimeria, they may develop coccidiosis.

Large numbers of Eimeria cause damage to the bird's intestinal lining, resulting in leakage of proteins, including plasma into the bowel. This causes a disruption of digestive processes or nutrient absorption, dehydration, anemia, and increased susceptibility to other disease agents.

Clinical Signs of Coccidiosis in Chickens


Signs of coccidiosis in chickens varies depending on the number and species of Eimeria present, site of infection, and the age and overall health status of the bird.
Dysentery is a common sign that occurs when infections are severe---consisting of the appearance of blood and mucus in the feces. Affected birds may also appear fluffed up and depressed (will show decreased activity levels and disinterest in normal chicken activities). They may experience weight loss or show reduced weight gain if affected during early growth.

How Coccidiosis is Diagnosed in Chickens


Coccidiosis is diagnosed in chickens through a fecal test on the chicken's droppings. Eimeria eggs can be identified when the feces is looked at with a microscope. A Complete Blood Count (CBC) may show decreased red blood cell and total protein level counts in affected birds.

Coccidiosis Treatment for Chickens


Treatment of coccidiosis involves several important components:
  • Anticoccidial agents. It is initially important to control the coccidia with an anticoccidial agent such as amprolium or toltrazuril, in accordance with the manufacturers recommendations.
  • Antibiotics: It is important to control secondary bacterial growth by concurrently administering antimicrobials such as tylosin or amoxicillin. When coccidiosis damages the intestinal wall, it leaves the bird more at risk of developing secondary infections, such as necrotic enteritis.
  • Supportive care: It is very important to keep the bird hydrated and comfortable.
  • Environmental/Management Changes. Slow down oocyst sporulation within the environment where birds live by regularly cleaning the area where chickens live, by removal of the feces and soiled bedding, ensuring it is kept dry (perhaps install better drainage or roof to prevent rain), and/or rotate birds to different areas often. Do not overcrowd birds.
There has been an increased emergence of drug-resistant strains of Eimeria, especially after prolonged uses of the drug. Therefore, it is important to conduct a follow up fecal test following treatment, to evaluate whether the drug was effective against the particular strains of Eimeria present.

Clinical Signs

Hunched up with ruffled feathers
Depression
Pale
Change in droppings (water, mucous, and blood)
Loss of appetite
Loss of condition
Diarrhea/watery droppings
Stunted growth rate

Diagnosis

  • History
  • Clinical signs
  • High fecal oocyst counts (over 50,000 oocysts/gram of feces)

Treatment

NameSummary
AmproliumMost be given for 5 days straight to be effective. Note - When administered, it is important NOT to concurrently give supplements that contain vitamin B, for it will override the effects of the drug.
Toltrazuril6 mg/kg added to drinking water for 2 days. Note - When Toltrazuril is administered, it is important NOT to concurrently give supplements that contain vitamin B, for it will override the effects of the drug.
Sulphonamides2-3 days of daily treatment and repeated in 5 days.
Antioxidants
Supportive careKeep hydrated and comfortable. Make sure bedding stays DRY to slow down oocyst sporulation.
Environmental modificationsImprove sanitary practices by regularly cleaning the environment where birds are kept, minimizing persistent mud and wetness, and risk of fecal contamination in feeders and waterers. Do not overcrowd birds. Rotate runs. Treat the ground with dilute bleach or lime to reduce oocysts, followed by monthly rototilling of the soil.
AntibioticsTylosin or amoxicillin; May be beneficial to help control secondary bacterial growth, which could otherwise lead to necrotic enteritis.

Support

Prevention

  • Clean, disinfect, and refill waterers with fresh water daily, to prevent buildup of potentially pathogenic organisms. Position them so as to minimize water spillage onto bedding litter, as moisture promotes the growth of cocci.
  • Keep area dry.
  • Do not overcrowd birds.
  • Don't keep birds in the same enclosed area for extended lengths of time, rotate them periodically to another area
  • Keep chickens of different ages separated
  • Practice good sanitation and minimize accumulation of feces by cleaning at least once a week.
  • Design roost areas over screened dropping pits for feces, to minimize contact birds have with feces.
  • Provide apple cider vinegar in the drinking water (1 tablespoon per 5 gallons of water)
  • Purchase resistant poultry breeds, such as the New Hampshire, Rhode Island Red or Leghorns

Scientific References

Good Overviews

Age Range

Usually occurs in chickens between 1-4 months of age. Chicks under 1 week cannot have coccidiosis.

Risk Factors

  • Overcrowding
  • Chronic wet environment
  • Mixing chickens of different ages together
  • Unsanitary living conditions (large accumulation of feces)
  • Stress (recent transport, change of ownership or flock mates, sudden temperature change, bullying, stalking predators, improper handling, injury, etc.)
  • Concurrent disease
  • Poor immune status
  • Introduction of a new chicken into the flock
  • Letting chickens recovering from an illness or injury back out into the flock prior to finishing the course of medication.

Seasonality

WinterSpringSummerAutumn