Morphological characterisation of a novel Eimeria sp. parasite in South Island takahē (Porphyrio hochstetteri)

ABSTRACT

Aims

A novel Eimeria sp. is described from the endangered South Island takahē (Porphyrio hochstetteri).

Methods

Faeces were collected from South Island takahē in managed populations across two geographic locations within New Zealand, linked by extensive bird translocation. Faecal flotations were performed and oocysts collected were sporulated in sterile water at 25°C for 5 days. Morphometric measurements including length:width (L:W) ratios of oocysts and sporocysts were made of 65 oocysts using light microscopy under oil immersion. A retrospective histological review of archived post-mortem material from takahē was performed.

Results

Oocysts were ovoid (mean L:W 1.2 (SD 0.1)) with mean dimensions of 18.0 (SD 0.8) × 15.2 (SD 0.7) μm, and walls 0.9 (SD 0.1) μm thick at the equator. A micropyle was absent and the oocyst residuum was present as a granular spherical mass. Four sporocysts were present and were elongate ovoid in shape (mean L:W ratio 1.5), with mean dimensions of 9.7 (SD 1.1) × 6.3 (SD 0.7) μm and each containing two sporozoites with anterior and posterior refractile bodies. This morphological description is distinct from other Eimeria spp. described in hosts of the family Rallidae. The retrospective review of tissue was hindered by the poor quality of the preserved gut tissue, but coccidial organisms were able to be identified in the caudal ileum and caecum of a single bird.

Conclusions

A novel Eimeria sp. was identified in the faeces of takahē. We propose this species be named Eimeria takahe.

Clinical relevance

Conservation of the endangered South Island takahē is reliant on human management of populations under varying degrees of captive management. An understanding of diseases affecting this host, including parasites and their identification as unique to the takahē or introduced from interactions with other hosts, is essential to the maintenance of overall bird health and informs management decisions in this recovery programme.Abbreviations: L:W: Length:width

KEYWORDS:

• Takahē
• Porphyrio hochstetteri
• Coccidia
• Eimeria
• Rallidae

Acknowledgements

The authors would like to thank Ngāi Tahu, Phil Marsh, and other staff of the Department of Conservation Takahē Recovery Group, Stuart Hunter and Mark Jolly for their assistance with this work. Funding was provided by the Tāwharau Ora, School of Veterinary Science, Massey University via the Postgraduate Research Fund and Avian Health Fund.