Coccidiosis E. acervulina Upper Int ...

Coccidiosis E. acervulina Upper Intestinal Subclinical Infections in Laying Hens

Coccidiosis E. acervulina Upper Intestinal Subclinical Infections in Laying Hens

This species is the most frequently encountered in commercial poultry. Light to moderate infections may produce little effect on weight gain and feed conversion. Egg production may drop in laying hens. Watery and mucous droppings may be observed. (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. Outbreaks of any species in layers can reduce or eliminate egg production for several weeks. (1, 2)

An infection with species of coccidia is a predisposing factor for Clostridium sp. infection. Colonization of the 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)

Observed Clinical Signs Happenings

Egg drop

  • Egg production declines gradually
  • Egg production may be depressed in laying hens


  • Watery and mucoid droppings may be seen as early as 4 days post exposure

Internal egg quality

  • Yolk colour decreased or yolk discolouration or paler yolks may be present
  • Yolk colour variable

Coccidiosis E. acervulina Upper Intestinal Subclinical Infections in Laying Hens DOES NOT show, exhibit or manifest any of the following clinical signs happenings:

  • Egg production declines rapidly
  • Mortality above the standard
  • 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
  • Feathers abnormalities
  • Feed Consumption Changes
  • Shell quality



Causing Agents
Protozoal Infection parasites Eimera acervulina. Intestinal coccidiosis
Affected Systems/Organs
Intestinal Tract Small intestine
Ingestion of viable sporulated oocysts is the only natural method of transmission. Oocysts can be spread mechanically by many different animals, insects, contaminated equipment, wild birds and dust.
Mainly Affects
Egg production and Performance
Adequate Pullet coccidial immunization program. Anticoccidial drugs. Good hygiene practices, vaccinations, coccidiostat in feed or water.
Suggested Actions
  • Can be managed with feed additives, off-the-shelf medications
  • Can be managed with vaccination programs
  • 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 1070
  2. David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 1151
  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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