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

AIMS: A novel Eimeria sp. is described from the endangered South Island takahe (Porphyrio hochstetteri). METHODS: Faeces were collected from South Island takahe 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 takahe 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 takahe. We propose this species be named Eimeria takahe. CLINICAL RELEVANCE: Conservation of the endangered South Island takahe 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 takahe 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.

Prevalence of Candidatus Mycoplasma haemolamae, bovine viral diarrhoea virus, and gastrointestinal parasitism in a sample of adult New Zealand alpaca (Vicugna pacos).

AIM: To determine the prevalence of infection with Candidatus Mycoplasma haemolamae (Mhl), antibodies to bovine viral diarrhoea virus (BVDV), and BVDV antigen, and the prevalence of animals with elevated faecal nematode egg counts (FEC) in a sample of adult New Zealand alpaca (Vicugna pacos). METHODS: Blood samples were obtained from 175 alpaca, collected from 15 farms around New Zealand, and from 31 samples sent to a diagnostic laboratory for routine haematology. Blood smears (n=170) were examined microscopically for the presence of haemoplasma, and DNA was extracted from whole blood (n=206) for real-time PCR testing for Mhl. Packed cell volume (PCV) was determined for 193 samples. Serum samples (n=195) were tested for BVDV antibody using ELISA, and for BVDV antigen using a real-time PCR assay. Faecal samples were collected from 143 animals; FEC were measured, and samples pooled for larval culture. RESULTS: No haemoplasma organisms were present on blood smear examination. Of the 206 blood samples, two (from the same farm) were positive for Mhl by real-time PCR testing, giving a prevalence of infection with Mhl of 0.97%. Of the 195 serum samples tested, four (2.1%) were positive for antibodies to BVDV; animals with BVDV antibodies were from 3/15 (20%) farms, none of which farmed cattle. None of the serum samples were positive by PCR for BVDV antigen. The median FEC was 50 epg (min 0, max 4,700), with 55/143 (38.5%) samples having 0 epg, and 33/143 (23.1%) having ≥250 epg. Haemonchus spp. were the most common nematodes present in faecal larval cultures from the North Island. Log10 FEC was negatively associated with PCV (p=0.02), and was higher in males than females (p<0.001), and in animals that were positive compared with negative for Mhl (p=0.022). CONCLUSIONS AND CLINICAL RELEVANCE: The number of alpaca infected with Mhl was low, as was the seroprevalence of BVDV. Gastrointestinal parasitism was, however, a common finding in this sample of New Zealand alpaca.

Efficacy of short-term feeding of sulla (Hedysarum coronarium) to young goats against a mixed burden of gastrointestinal nematodes.

The aim was to investigate the efficacy of feeding sulla to young goats (<6 months of age) against a naturally acquired infection of gastrointestinal nematodes. Eleven goats were removed from the field, housed and were randomly divided into two treatment groups. Group 1 (n = 5) was fed a diet comprising lucerne-based pellets and aged hay. Group 2 (n = 6) were fed a diet of only sulla offered ad lib. The sulla contained 2.6% free condensed tannins (CT), 1.8% protein-bound CT and 0.1% fibre-bound CT. Goats in Gp 2 ate the sulla very readily from the first day. The goats were fed these diets for 10 days, then killed and total worm counts obtained. The arithmetic mean worm counts (in parentheses) for Gp 1 and Gp 2, respectively, were Teladorsagia circumcincta (5792, 5690), Trichostrongylus colubriformis (272, 262), T. vitrinus (1060, 1804) and Trichuris spp. (32, 30). There were no significant differences (p > 0.05) between any of these treatments. Short-term feeding of sulla had no effect on mixed burdens of gastrointestinal nematodes.

Lack of efficacy of monepantel against Teladorsagia circumcincta and Trichostrongylus colubriformis.

After reports of the apparent failure of monepantel to reduce the egg counts of goats on a farm in the lower North Island of New Zealand, faecal egg count reduction tests were conducted in goats and lambs resident on the property, and a confirmatory, slaughter study was conducted using 12 sheep, sourced elsewhere, that were grazed on the farm for approximately 5 weeks. In the egg count reduction test in goats, 8 animals were given monepantel at 3.9 mg/kg (just over 1.5× the sheep dose rate of 2.5mg/kg), whilst four received 7.7 mg/kg (just over 3× the sheep dose). In the egg count reduction test in sheep, 15 lambs were treated with 3.0mg/kg of monepantel. For the confirmatory study, the sheep were housed indoors for 2 weeks before half were treated with 2.9 mg/kg monepantel and the animals were killed for worm counts 9 days later. There was no evidence of efficacy in either egg count reduction test, or in the goats, the two dose rates used appeared equally ineffective. Likewise, there were no significant reductions in egg counts or worm burdens in the slaughter study. Monepantel was ineffective against at least two gastrointestinal nematode species, Teladorsagia circumcincta and Trichostrongylus colubriformis. These findings represent the first report from the field of resistance having developed to the anthelmintic monepantel with severe resistance developing in more than one species after being administered on 17 separate occasions to different stock classes and in less than 2 years of the product first being used on the farm in question.

Health screening for a translocation of captive-reared tuatara (Sphenodon punctatus) to an island refuge.

AIMS: To screen tuatara undergoing translocation from a captive crèche to an island refuge for evidence of health and known diseases, and apply basic epidemiological techniques to assess the significance of disease test results. METHODS: Tuatara (n=353) were physically examined and samples were taken from a random selection (n=30) for estimated white cell counts, screening for haemoparasites, and culture for Salmonella, Yersinia, Aeromonas and Campylobacter spp. Direct faecal smears were carried out on-site, and faecal floats were later performed to assess levels of endoparasitism with helminths and protozoa (n=69). Modified Ziehl-Neelsen staining was used to screen faecal smears, and positive specimens were further screened using an immunofluorescence antibody (IFA) test for Cryptosporidium oocysts. RESULTS: There was no evidence of external parasites on any of the animals examined and only one animal had a gross abnormality. All estimated white cell counts were in the range 2.8- 17.5 x 10(9)/L. No haemoparasites were observed. There were no enteric pathogens cultured, indicating the intestinal carriage of these bacteria in the tuatara was <9.4%. Of the 69 individual faecal samples examined, 12 (17%) had unidentified coccidial oocysts, 21 (30%) had nematode ova of various kinds, and 12 (17%) had intestinal carriage of motile protozoa consistent with Trichomonas spp and another unidentified organism. Nineteen (28%) tuatara had acid-fast oocysts present; however, IFA staining failed to detect any Cryptosporidium oocysts. CONCLUSIONS: Our understanding of the diversity of gastrointestinal endoparasites affecting tuatara is inadequate as many of the parasite ova seen could not be identified. This is the first record of tuatara as a host for Trichomonas spp of protozoa in the gastrointestinal tract.

The effect of repeated doses of toltrazuril on coccidial oocyst output and weight gain in suckling lambs.

Coccidial oocyst output and liveweight were monitored in 43 pairs of lamb twins over a 10-week period during September-November 1992. One of each set of twins was treated orally with toltrazuril (20 mg/kg) weekly while the other was an untreated control. The oocyst output was significantly lower (P < 0.01) and the weight gain over the trial period was significantly greater (P < 0.05) in the treated group than in the control group.

Multiple resistance in goat-derived Ostertagia and the efficacy of moxidectin and combinations of other anthelmintics.

Faecal egg count reduction tests were used to identify a strain of Ostertagia circumcincta/trifurcata complex in goats which was resistant to: ivermectin (at 0.2 mg/kg and 0.4 mg/kg orally), oxfendazole (at 5 mg/kg orally), levamisole (at 12 mg/kg orally) and fenbendazole (at 5 mg/kg orally) combined with levamisole (at 9.4 mg/kg orally). The percentage reductions achieved in these faecal egg count reduction tests were respectively 27%, 83%, 82%, 79% and 82%. Moxidectin (at 0.2 mg/kg by subcutaneous injection), fenbendazole (at 10 mg/kg orally) combined with levamisole (at 18.8 mg/kg orally), ivermectin (at 0.4 mg/kg orally) combined with oxfendazole (at 10 mg/kg orally) and ivermectin (at 0.4 mg/kg orally) combined with levamisole (at 12 mg/kg orally) were effective in removing these nematodes in goats as determined by faecal egg count reduction tests. These drenches achieved reductions of 100%, 100%, 98% and 100% respectively.