Coccidiosis is a common and significant disease affecting short-beaked echidnas (Tachyglossus aculeatus) in man­aged care.

Coccidiosis was identified in approximately one-third of all echidna cases in the ARWH (2024) and was the cause of death in 50% of all echidnas with coc- cidiosis. It can present as subclinical, enteric or systemic disease, with pathogenicity ranging from mild to fatal.

Coccidia are ubiquitous, complex protozoan organ­isms belonging to the phylum Apicomplexa. The Eimerii- dae Family contains two genera of veterinary importance: Eimeria, consisting of more than 2000 species, and Isos- pora (Slapeta and Morin-Adeline 2011). Coccidia are generally host-specific, although each host species may be parasitised by several coccidia species (Barker et al. 1988).

The Eimeria spp. that parasitise marsupials, and pre­sumably monotremes, are thought to belong to a clade that diverged from the major clade of eutherian host-spe­cific coccidians and have evolved to infect their hosts and to survive the extremes of Australian climates and habi­tats for millions of years (Spielman 2016).

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