Coccidia

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PARASITES
PROTOZOA



Eimeria spp.

Isospora spp.

Coccidia of Poultry

Other Avian Coccidia

Coccidia of Cattle

  • Many species affect cattle
  • Cattle under a year old are usually infected sporadically
  • 2-3 week prepatent period
  • Eimeria bovis
    • Endogenous stages in central lacteal of villi and epithelial cells of caecum and colon
    • Causes diarrhoea and enteritis
    • Oocysts are 28x20m
  • Eimeria zuernii
  • Mainly occurs in calves in poor conditions and brought-in calves
    • Also occurs in suckler calves turned out in spring
  • Eimeria alabamensis associated with diarrhoea in calves after spring turnout
  • Can be concurrent with cryptosporidium, viral and bacterial agents

Diagnosis

  • History, clinical signs, diarrhoea (often with blood) and a decrease in weight gain
  • Post-mortem
    • Diffuse inflammation and thickening of caecal mucosa (and sometimes ileal and colonic mucosa)
    • Masses of gamonts and oocysts in scrapings
  • High faecal oocyst count
    • However, healthy animals can pass millions of oocysts from mixed species infections which have no pathogenic significance
    • Animals may die before oocysts are shed

Control

  • Improve husbandry
    • Improve sanitation
    • Increase bedding
    • Raise faecal and water troughs to avoid faecal contamination
  • Preventative in-feed medication
    • E.g. Decoquinate
  • Injectible antiprotozoals may limit oocyst production but animals should still be moved to a clean environment
    • E.g. Sulphamethoxypyridazine

Coccidia of Sheep

  • 11 different Coccidia species although only two are of clinical significance
    • Giant schizonts visible as white spots
  • 2 week prepatent period
  • Disease frequently seen in lambs under 6 months old
    • More often in twins and triplets when single lambs
  • Oocyts from ewes (immune carriers) accumulate in poorly managed litter or around feed and water troughs
  • Lambs born early in the year amplify the parasite problem increasing the parasite risk to lambs born later in the year
  • Affected lambs may die before oocysts are found in the faeces
    • Post-mortem diagnosis difficult
  • Different species of Eimeria occurs in sheep and goats
  • Infection may be coincident with Neospora or Cryptosporidium infections
    • Mixed infections complicate the diagnosis as oocyst differentiation is difficult
  • Other non-pathogenic species can cause papillomatous mucosal growths

Control

  • Improve husbandry
    • Avoid overcrowding
    • Decrease stress
  • Improve hygiene by dagging ewes
  • Avoid mixing lambs of different ages
  • Preventative measures include creep feeding lambs with decoquinate or oral dosing with diclazuril when lambs are 4-6 weeks
    • A second dose can be given after 3 weeks

Coccidia of Goats

  • Many Eimeria species
  • 2 Eimeria are pathogenic
  • Different species of Eimeria occurs in sheep and goats

Coccidia of Horses

  • Only one atypical Eiemria
  • Forms large subepithelial gametocytes in villi
  • Large, dark coloured oocysts
    • Approximately 12μm
  • Besnoitia bennetti in larynx of horses

Coccidia of Pigs

  • Many species of Eimeria and Isospora
  • Only Isospora suis is of clinical pathogenic importance
  • Causes sporadic, serious and sometimes fatal disease in unweaned piglets
  • Very short 1 week prepatent period
  • Diarrhoea starts before oocysts are shed in faeces
    • Ante-mortem diagnosis is difficult
  • Death usually occurs after parasites have left the host
    • Post-mortem diagnosis difficult
    • Isospora infections are self-limiting

Coccidia of Dogs

  • 2 common and 2 less common Isospora species
  • Occasionally can cause disease
  • Little pathogenicity
  • Even if faecal oocyst count is high, other causes of diarrhoea should be looked for
  • Hepatozoon americanum and subclinical H. canis in periosteal bone formation
    • Both are Tick borne diseases
      • H. canisRhipicephalus sanguineus
      • Ticks become infected by ingesting a blood meal containing macrophages and neutrophils infected with the parasite gamonts -> sexual replication in the gut of the tick -> oocysts containing infective sporozoites -> dogs ingest the tick  schizogony occurs in numerous tissues


Coccidia of Cats

Coccidia in Cat Faeces - Joel Mills
  • 2 common Isospora species with little clinical significance
  • Oocysts in faeces have to be distinguised from those of Toxoplasma (smaller) and Sarcocytis (sporulated or naked sporocyts in faeces)

Coccidia of Rabbits

  • 3 pathogenic Eimeria species
    • 2 in the caecum
    • 1 in the bile duct
  • Eimeria steidae
    • Parasitises the bile duct epithelium
    • Travels via the bile duct to the liver where it forms large white nodules
    • Oocysts travel in the bile and are passed out in the faeces
    • Causes ascites, diarrhoea, weight loss and polyuria
  • Serious disease of both pet and farmed rabbits
  • Treatment is by administration of drugs in drinking water
    • E.g. Toltrazuril
  • Hygiene is the best method of prevention to prevent sporocysts from sporulating
  • Medicated feed can be used in commercial units
    • E.g. Rabenidine