COCCIDIOSIS

Poultry coccidia are strictly host-specific and affect specific intestinal locations. Coccidiosis is caused by protozoa of the phylum Apicomplexa, family Eimeriidae. Coccidia are almost universally present in poultry-raising operations, but clinical disease occurs only after ingestion of relatively large numbers of sporulated oocysts by susceptible birds.

Causative Agent(s)

Eimeria necatrix and Eimeria tenella are the most pathogenic in chickens

Clinical Presentation and Epidemiology

Both clinically ill and recovered birds shed oocysts in droppings. Transmission could also be by mechanical carriers.

Clinical signs Range from decreased growth rate to visibly sick birds with severe diarrhoea, decreased egg production and high mortality.

Diagnostic Considerations

Demonstration of oocysts in faeces or intestinal scrapings which must correlate with clinical disease. Fresh necropsy findings are also helpful.

Management and Treatment

Can maintain on wire floors to separate birds from droppings. Protective immunity develops over time, and older birds are usually more resistant than young birds. Controlled exposure is routinely used to immunize broiler breeder flocks. Litter moisture content (low) is critical in the control of coccidiosis. Vaccinate birds appropriately.

Various anticoccidials are available and are usually given in feed (preventative) or water (treatment). Prophylactic use is preferred because most of the damage occurs before signs are obvious. Drugs include amprolium 125ppm PO for 3-5 days, clopidol 125ppm for 1-3 weeks PO, sulphonamides 0.0175-0.25% for 2-3 days, then plain water for 3 days, then medicated water for 2 days, halofuginone hydrobromide 2-3mg/kg PO, nicarbazin 125ppm PO, nitrobenzamides 0.0125% PO for 6 days, and robenidine 33ppm PO, Toltrazuril 7mg/kg PO for 2 days, Diclazuril 0.3mg/kg PO for 2 days. Ionophore antibiotics (monensin 100-110ppm PO, salinomycin 500g/ton of feed, lasalocid 90-125ppm PO, narasin 60-80mg/kg PO) are the mainstay.