Coccidiosis

It is a protozoan disease, caused by Eimeria species, resulting in enteritis, debility and anaemia.

Etiology: It is caused by E. zuernii, E. bovis and E. ellipsoidalis in bovines; E. arloingi and E. ahsata in sheep; and E. arloingi and E. faurei in goats. The disease occurs in calves, lambs or kids and is more prevalent in humid wet climate and overcrowded stock.

Pathogenesis: The ingested oocysts produce sporozoites which invade endothelial cells of villi of small intestine and develop into asexual schizonts. After maturation of schizonts, merozoites are released by rupture of epithelial cells. New epithelial cells are invaded. Its life cycle occurs in alimentary mucosa. Different species of parasite remain at different sites of intestine.

Clinical signs: Initially animals show mild fever but later on temperature becomes normal or subnormal. There is sudden onset of foul smelling diarrhoea which contains excess of mucus and blood. It may appear as a dark tarry staining of faeces or red streaks of blood or clot. Tenesmus, weakness, loss of appetite and anaemia are also noticed in affected calves or lambs. In younger animals suffering from severe form of the disease, nervous signs are seen like hyperesthesia, muscular tremors and convulsions.

On postmortem examination, haemorrhagic enteritis, thickening of mucosa of intestine and congestion are noticed. Small white cyst like bodies is formed at the tip of the villi.

Diagnosis: It is diagnosed by faecal examination for the presence of oocysts, and clinical sign.

Treatment: Large number of coccidiostats is available for use in calves or lambs. Sulfadimidine can be given in calves and lambs @ 140 mg/kg body weight/ day orally for 3 days. Nitrofurazone @ 15 mg/kg body weight/day orally for 7 days or amprolium @10 mg/kg body weight/day orally can be given for 5 days. Lambs can be treated with monensin @ 2 mg/kg body weight orally for 15 days.

Control: Coccidiostats are used at a lower dose rate for a long period for the prevention of disease. These drugs are mixed in feeds to avoid cumbersome individual dosing of the animal. Sulphadimidine is given to calves in feed @ 35 mg/kg or in lambs @25 mg/kg body weight for 1 to 2 week, respectively, whereas amprolium in calves and lambs is used @ 5 and 50 mg/kg body weight, respectively for 3 weeks. Monensin in calves and lambs is used @ 20 mg/kg feed. General hygienic measures, isolation of infected animals and avoidance of overcrowding should be practiced for the prevention of disease.