Failure to detect Salmonella species in a population of wild tuatara (Sphenodon punctatus)

Abstract

AIM: To assess the prevalence of faecal excretion of Salmonella serovars by wild tuatara (Sphenodon punctatus) on Stephens Island, New Zealand.

METHODS: One hundred cloacal swabs obtained as part of health-screening for the translocation of adult tuatara from Stephens Island were subjected to general aerobic culture and enrichment, and cultured specifically for Salmonella spp.

RESULTS: No Salmonella spp were cultured from any of the cloacal samples, which suggests that, at the 95% confidence interval, the maximum prevalence of tuatara in the island population that were shedding Salmonella spp not detected by our sample size was 1.5%. Mixed bacteria were grown from the 70 cloacal swabs cultured aerobically. A predominant organism was evident in 30 cultures, and these were identified as Hafnia alvei type 1 (n=16) and type 2 (n=7), Corynebacterium spp (n=4), Klebsiella oxytoca (n=2), and Moraxella spp (n=1).

CONCLUSIONS: The absence of intestinal carriage of Salmonella spp by the tuatara sampled in this study may indicate either lack of exposure, or an innate resistance to intestinal colonization in tuatara. The significance of the other bacteria cultured as potential pathogens to the tuatara and as zoonotic risks is also uncertain. Wildlife managers should screen translocated reptiles for Salmonella spp, and thereby avoid exposing wild and managed populations to infection.

KEY WORDS:

• Zoonosis
• reptile
• tuatara
• salmonellosis
• Hafnia

Acknowledgements

This work was carried out with the logistical support of Karori Wildlife Sanctuary and the Department of Conservation. The authors thank the Ngati Koata iwi, Peter Gaze and Kate McInnes from the Department of Conservation, the research teams at Victoria University and the New Zealand Wildlife Health Centre at Massey University, numerous volunteers, and David McLelland for review of the manuscript.