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Avian Coccidiosis


Coccidiosis is a parasitic disease caused by apicomplexan protozoa of the genus Eimeria (known as cocci).


There are seven different species of Eimeria that affect chickens---E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatric, E. praecox and E. tenella. Each species has different regions in their gastrointestinal system, where they will inhabit and feed off of. Depending on the species, amount present, site of infection, age, and health status, coccidiosis can cause enteritis and mild to severe damage to the intestinal tract, including:
  • Fluid loss and malabsorption of nutrients.
  • Inflammation of the intestinal wall with pinpoint hemorrhages and sloughing of epithelia.
  • Hypoproteinemia
  • A decline in plasma concentrations of the hormones thyroxine and triiodothyronine.
  • Increase in plasma corticosterone and prolactin.
  • Complete villar destruction resulting in extensive hemorrhage and death.

Life cycle

Eimeria are maintained in flocks through a complex life cycle. Chickens become infected initially by consuming sporulated oocysts present in contaminated environments. Once infected with the parasite, these chickens will shed the oocysts produced by the organism, thus contaminating the environment. The cycle continues.Eimeria have a short life cycle, varying between 4 to 6 days depending on the species.
Coccidial oocysts require moisture to develop into the infective stage.

Usually, adult chickens build up a resistance, but can occasionally be susceptible, especially if they are stressed or have concurrent disease.


Coccidiosis has traditionally been controlled in the commercial poultry industry through the use of coccidiostatic or anticoccidial drugs (ionosphere antibiotics or chemoprophylactics). This method is still widely used today in the United States, where it is sold under the label 'Medicated chick feed' at feed stores. This method of controlling coccidiosis was banned by the European Union in 2006, due to concerns regarding antimicrobial resistance.

Clinical Signs

Weight loss
Stunted growth
Loss of appetite
Ruffled feathers
Mucousy, frothy or bloody droppings
Hunched stance w/ drooping wings


  • History
  • Fecal exam
  • RT-qPCR


Supportive careIsolate the bird from the flock and place in a safe, comfortable, warm location (your own chicken "intensive care unit") with easy access to water and food. Limit stress. Call your veterinarian.
Mannanoligosaccharide (yeast cell wall; YCW)0.05% of feedGomez-Verduzco et al., 2009
Probiotics20 mg/bird per day, added to drinking waterM Ritzi et al., 2016
Herbal Remedies/Essential Oils
Pomegranate (Punica granatum)Added to drinking water - pericarp extract for 5 daysB. Berto et al., 2014
Oregano (Origanum vulgare) essential oil500 ppm of feedMohiti-Asli et al., 2015
Beggar's ticks (Bidens pilosa) powder0.5% of feedYang et al., 2014; C Chang, et al., 2016
Galla Rhois (GR)1% of feedLee et al., 2012
Sweet wormwood (Artemisia annua) leaf powderAdded to feed at 1.5-5% over a period of 3 to 4 weeksAllen et al; Dragan et al., 2014; E Brisibe et al., 2008
Sweet wormwood (Artemisia annua) + VaccineThere is a live vaccine available, sometimes given concurrent with 1% Artemisia annua added to the diet over a period of 5 weeksT Abbas 2012
Ground green tea (Camellia sinensis)Added to diet at 0.5-2% of feedT Abbas 2012
Anticoccidial Drugs
Diclazuril200 ppm in feedMohiti-Asli et al., 2015

117-234 g/ton in feed.
Note can interfere with thiamine absorption
K Marx
Clopidol-25%114-227 g/ton feedK Marx
Monensin sodium90-110 g/ton in feed for 8 weeksK Marx
Lasalocid68-113 g/ton of feedK Marx
Sulfadimethoxine (12.5% solution)1 oz/2 gal drinking water for 6 daysK Marx
Sulfadimethoxine/Ormetoprim10 ppm in feedK Marx
Sulfaquinoxaline1 oz/4 gal drinking water for 3 days on/2 days off, 2 days on/2 days off, etc. for 7 days total medicationK Marx


  • 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.
  • Do not overcrowd
  • 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

Coccidiosis occurs most frequently inchickens between 4 to 5 weeks of age.

Risk Factors

  • Feeding whole wheat greater than 300 g/kg of diet
  • Overcrowding
  • Mixing chickens of different ages together in a small, confined area
  • Unsanitary living conditions
  • Unbalanced or nutrient deficient diet
  • Spillage of waterers onto bedding litter