What does coccidia mean?
Coccidia are single-celled parasitic organisms belonging to the subclass Coccidia, a group of protozoans that invade the intestinal cells and sometimes other tissues of birds, mammals, reptiles, and fish. The word is the plural form of 'coccidium', reflecting the fact that infections typically involve large numbers of the tiny parasites rather than a single organism. In veterinary practice, coccidia are notorious for causing coccidiosis, a disease marked by diarrhoea, weight loss, and sometimes death, especially in young livestock such as chicks, lambs, calves, and puppies. Because the parasites spread through contaminated food, water, and bedding, outbreaks are a constant concern on farms and in kennels. Although the term belongs mainly to scientific and agricultural registers, it is useful for anyone reading about animal health, since coccidia are among the most widespread and economically significant parasites of domesticated animals worldwide.
nounA plural noun referring to single-celled parasitic protozoans of the subclass Coccidia, which infect the intestinal tracts and other tissues of animals and can cause the disease coccidiosis.
- Single-celled parasitic protozoans of the subclass Coccidia that infect the intestines and tissues of vertebrate hosts.
- (In older classification schemes) a taxonomic group or order of sporozoan protozoa now treated more broadly within apicomplexans.
"The outbreak of diarrhoea among the lambs was traced to an infestation of coccidia in their drinking water."
"Poultry farmers routinely treat litter to control coccidia, which spread rapidly through crowded flocks."
"Under the microscope, the vet identified oocysts of coccidia in the puppy's stool sample."
'Coccidia' is already the standard plural of 'coccidium'; it functions collectively and takes a plural verb when treated as countable ('the coccidia were observed').
"Several species of coccidia infect domestic poultry."
Every chicken farmer fears them: coccidia are microscopic one-celled parasites whose name literally means 'berry-like', thanks to their round shape under the microscope.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of coccidia
The word 'coccidia' derives ultimately from the Greek 'kokkos', meaning a grain, seed, or berry. Nineteenth-century scientists coined 'coccidium' as the singular form, choosing the name because these parasites appeared as small round bodies resembling berries under the microscope. The term entered scientific Latin alongside related coinages such as 'coccus', used by bacteriologists for spherical bacteria drawn from the same Greek root.
Related word forms
How coccidia is actually used
Used almost exclusively in veterinary science, microbiology, and animal husbandry rather than everyday speech. It is the plural of 'coccidium'; writers referring to a single organism should use 'coccidium' or the adjective/noun 'coccidian'. The term often appears in discussions of livestock health, particularly poultry, cattle, sheep, and rabbits.
Easily confused with coccidia
Cocci are spherical bacteria such as staphylococci, whereas coccidia are parasitic protozoans that infect animals.
Coccidia are the parasites themselves; coccidiosis is the disease those parasites cause.