coccidiosis

Coccidiosis is a disease caused by protozoan parasites of the genus Eimeria (and related coccidia) that infect the intestinal tract of a range of animals, most notably poultry, cattle, sheep, goats, and pigs. Different Eimeria species are typically host-specific, so the parasites that infect poultry differ from those in ruminants. In humans, coccidial infections are rare and usually involve different genera such as Isospora (Cystoispora) rather than the animal coccidia.

The parasites have a direct life cycle. Oocysts are shed in feces and contaminate the environment. After sporulation, ingested oocysts release infective stages that invade intestinal epithelial cells, multiplying asexually and sexually, causing cell damage, inflammation, and disruption of nutrient absorption. The result is enteritis, malabsorption, diarrhea, dehydration, and poor weight gain or growth, with severity depending on the host species, immune status, and parasite load.

Diagnosis relies on the detection of oocysts in feces or characteristic intestinal lesions postmortem. In livestock and poultry, flotation techniques, fecal egg counts, histology, and, when available, molecular assays are used to identify the infecting Eimeria species.

Treatment and prevention involve anticoccidial drugs administered in feed or water, such as ionophores or sulfa-based compounds, and, in some settings, toltrazuril. Vaccines using live oocysts are available for poultry. Management measures include good sanitation, clean litter and water, proper stocking density, rotation of anticoccidial programs, and hygiene to reduce environmental contamination. Coccidiosis remains a significant economic concern in intensive farming due to production losses and costs of control. Zoonotic potential is low, reflecting strong host specificity of animal coccidia.