Coccidiosis E. tenella, Coccidiosis ...

Coccidiosis E. tenella, Coccidiosis Caecal Infection in Laying Hens

Coccidiosis E. tenella, Coccidiosis Caecal Infection in Laying Hens

Eimeria tenella is the best-known poultry coccidia, because of the recognizable lesions and often spectacular losses it causes in commercial broilers or layer pullets. (1, 2)

Eimeria tenella is the only species which causes caecal coccidiosis, one of the most easily recognized forms of coccidiosis. Infection can be acute and spread rapidly, resulting in mortality in a susceptible flock or coccidiosis control program failure for replacement birds. Eimeria tenella causes bloody droppings and onset of mortality in a flock. (1, 2)

Coccidiosis rarely occurs in layers and breeders during the laying cycle, because of prior exposure to coccidia and resulting immunity, if a flock is not exposed to a particular species early in life or immunity is depressed because of other diseases, outbreaks may occur after layers are moved to production houses.

E.necatrix along with E.tenella is the most pathogenic of the chicken coccidia. Droppings of infected birds often contain blood, fluid, and mucus. Some birds may show ruffled feathers. (1, 2)

Infections with mid-intestinal species of coccidia are a major predisposing factor for Clostridium sp. infection. Colonization of small intestine by Eimeria sp. may lead to intestinal mucosal damage which may then, in turn, provide natural substrates (plasma proteins) required for Clostridium sp. proliferation. (1, 2)

The possible role of bacterial products in mortality from coccidiosis is suggested by the lack of mortality from E. tenella in germ-free chicks. (1, 2)

Observed Clinical Signs Happenings



  • Low mortality or increases gradually
  • The onset of mortality in a flock is rapid

Dead birds

  • Good bodily condition (“full crop”)


Visibly sick birds

  • Few visibly sick birds
  • Depression


Droppings abnormalities

  • Droppings of infected birds often contain blood, fluid, and mucus



Coccidiosis E. tenella, Coccidiosis Caecal Infection in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:


  • High mortality or increases rapidly
  • Dead birds: Poor bodily  condition (“Skinny body”)
  • Many visibly sick birds
  • Flock behaviour activity change
  • Respiratory abnormalities
  • Neurological Nervous
  • Lameness or unusual movements, incoordination, ataxia
  • Eyes abnormalities
  • Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Earlobes, abnormalities (except eyes)
  • Body Parts (Neck, wings, breast, abdomen, shanks, legs, hocks, feet, joints, vent, and skin, abnormalities), skinny body, retarded growth, weight depression
  • Feed Consumption Changes
  • Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)
  • Shell quality defects
  • Internal Egg defects
Causing Agents
Protozoal infection by Eimeria tenella
Affected Systems/Organs
Digestive Track.Caeca
Mainly Affects
Mortality Performance
Adequate coccidiosis control program for replacement pullets. Coccidial drugs. Vaccines.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Technical assistance recommended
  • Can be managed with feed additives, off-the-shelf medications
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


  1. Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 1075
  2. David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 1156
  3. Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.
  4. Paul McMullin. 2004. A Pocket Guide to Poultry Health and Disease. First Edition.
  5. Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
  6. Donald D. Bell, Williams D. Weaver. 2009.  Commercial Chicken Meat and Egg Production. Fifth Edition.
  7. Gail Damerow 1994. The chicken Health Handbook.

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