Diagnosis and prevalence of ventricular nematodiasis in kiwi (Apteryx spp.) : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Veterinary Science at Massey University, Manawatū, New Zealand

Abstract

Only one species of nematode has been formally described from the ventriculus of kiwi (Apteryx spp.); a spirurid nematode of the Cyrnea genus. However, apart from its morphology, little is known about this parasite. This thesis describes investigations into its pathogenicity, prevalence and diagnosis. A case series examining four cases of ventricular nematodiasis in kiwi (VNK) highlighted that repeated faecal examinations did not detect the eggs of the ventricular nematodes. Diagnoses were achieved via gastroscopy or post-mortem histological examination of the ventricular wall. These cases illustrated how the lack of an accurate ante-mortem diagnostic technique limits what is known about the parasite responsible for VNK including its pathogenesis, transmission and management. Four-hundred and fifty samples were collected opportunistically from captive kiwi housing facilities over the course of eight months with the dual aims of refining diagnostic methodology and establishing the prevalence of the Cyrnea sp. nematode in captive kiwi faecal samples. These samples were obtained from 167 individual kiwi of four different subspecies across a wide age-range from nine different submission locations. An ante-mortem test to diagnose VNK was formulated and refined using coprological testing. The most sensitive method of detecting Cyrnea ova was centrifugal flotation in 80% zinc sulphate solution but examination of the centrifugal sediment from a 33% zinc sulphate solution was more accurate in quantifying the number of ova present. Centrifugal sedimentation reduces the time and effort required for sample processing, making it the efficient choice. The prevalence of ventricular nematode ova in faecal samples from captive kiwi was found to be 16.77% (95% CI) based on faecal flotation in 80% zinc sulphate solution. Using this method, kiwi aged 4 months or younger and those of the North Island brown (A. mantelli) species were the most likely to have detectable parasitic infection with Cyrnea spp. This research highlighted the importance of developing an accurate ante-mortem faecal test for the diagnosis of VNK. A viable preliminary test for laboratory use was developed and the prevalence of infection was examined in captive kiwi through faecal testing.