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Avian Coccidiosis

Coccidiosis is a destructive protozoan disease of predominately young chicks, and is characterized by symptoms of weakness, ruffled feathers, general unthriftiness, and sometimes bloody droppings. Affected birds are listless and show little to no interest in eating or drinking. As the disease advances, moderate to high mortality is common.

The disease is caused by infection with protozoa from the Eimeria genus (known as cocci). There are seven Eimeria species that affect chickens---E. acervulina, E. brunetti, E. maxima, E. mitis, E. necatric, E. praecox and E. tenella. Each has a specific site in the chicken's gastrointestinal system that it prefers to inhabit. Once ingested by chickens, Eimeria invade and destroy the protective lining of important organs within the bird's digestive system; causing increased mucus secretion, reduced nutrient absorption, blood loss, fluid leakage from damaged mucosa, impaired growth and feed utilization, and predisposes the birds to secondary infections. The severity of the disease various depending on the age of the chicken, number of parasites ingested, species of Eimeria, and immune health. When young chicks are infected, the illness can quickly become fatal, unless it is caught early and treated appropriately and aggressively.

Life cycle
Protozoa are maintained in flocks through a complex life cycle, predominately involving the continued ingestion of sporulated oocysts present in the external environment, and shedding of oocysts by infected chickens. 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. Eimeria are spread by contact with feces of infected birds. By keeping bedding litter dry and daily removal of feces, helps to inhibit their development. Usually, adult chickens build up a resistance, but can occasionally be susceptible, especially if they are stressed or have concurrent disease.

Disease history
For decades, most commercial poultry farmers worldwide relied on the use of coccidiostatic or anticoccidial drugs (ionosphere antibiotics or chemoprophylactics) to protect chickens from coccidiosis. They were added in low doses to the chicken feed, in order to control coccidiosis. However, Eimeria species developed resistance to these drugs over time, which is referred to as 'antimicrobial resistance'. In 2006, in response to the growing concern of antimicrobial resistance, the European Union (EU) put a ban on the use of antimicrobial growth promoters in poultry within EU countries, and on imported foods obtained from animals that were not fed with antibiotics and anticoccidial drugs. In the United States (US), there is no ban on the use of anticoccidial drugs, and at the moment they are still actively used in the commercial poultry industry across the US.


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


  • History
  • Fecal exam
  • RT-qPCR


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