Candida albicans infection in free-living populations of hihi (stitchbird; Notiomystis cincta)

Abstract

AIM: To describe the occurrence of candidiasis in hihi (stitch-bird; Notiomystis cincta) nestlings, and investigate the carriage and impact of Candida albicans infection in a free-living population of hihi.

METHODS: Mortality of nestlings was investigated in a reintroduced population of the endangered, endemic hihi at Zealandia: Karori Sanctuary, Wellington, New Zealand. Oral and faecal samples were collected from live hihi nestlings, for microbiological examination, between October 2008 and April 2009. All hihi that died and could be recovered were submitted to the New Zealand Wildlife Health Centre (NZWHC) at Massey University, for post-mortem examination. The results were compared with data obtained retrospectively from the National Wildlife Mortality (NWM) database for two other reintroduced populations of hihi on Mokoia and Tiritiri Matangi Islands.

RESULTS: Fifty chicks fledged from 82 eggs hatched during the 2008–2009 breeding season at Zealandia: Karori Sanctuary. Thirty-four live nestlings were sampled from 11 nests, and C. albicans was isolated from gastrointestinal swabs of 13 live nestlings from four nest sites. Eight (62%) of those nestlings survived to fledge, compared with 17/21 (81%) of those that tested negative (p=0.254; Fisher's exact test). Of the 32 hihi nestlings that died during the period of the study, 25 were recovered for necropsy. Histopathological examination revealed candidiasis was a factor in the deaths of four nestlings. An adult hihi that died during the period of the study at Zealandia: Karori Sanctuary was also found to have candidiasis. Retrospective analysis of data from the NWM database revealed candidiasis was also a factor in the deaths of five nestlings aged between 1 and 10 days from Mokoia Island, and of three nestlings <5 days old and one adult from Tiritiri Matangi Island.

CONCLUSIONS: Candida albicans was isolated from 38% of hihi nestlings sampled in this study, and vertical transmission of this organism from parent to offspring is likely to occur. Some colonised nestlings developed ventriculitis associated with Candida spp., but survival to fledging was not significantly different between nestlings that tested positive or negative, although the fate of birds following fledging was unknown.

KEY WORDS:

• Candida albicans
• hihi
• stitchbird
• Notiomystis cincta
• ventriculitis

Acknowledgements

The authors would like to thank Raewyn Empson, Matu Booth, the staff and volunteers of Zealandia: Karori Sanctuary for collecting and submitting samples and data, and the volunteers, research workers and DoC staff, including Rosalie Stamp, Shaarina Boyd and Richard Griffiths, who were involved with managing the populations of hihi on Mokoia and Tiritiri Matangi Islands, and who submitted some of the samples used in this survey. Jane Kerridge of Medlab Wanganui provided the facilities for much of the laboratory work. We acknowledge the outstanding technical help from staff at the Institute of Veterinary, Animal and Biomedical Sciences, including Elaine Booker, Evelyn Lupton and Nicola Wallace. Scholarship grants from the NZWHC Trust Research Fund, Graduate Women Manawatu Charitable Trust, and JP Skipworth (Ecology) Fund were used to fund some of the work undertaken.