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Item Theileria orientalis Ikeda infection detected in red deer but not dogs or horses in New Zealand.(2024-09-02) Lawrence KE; Gedye K; Carvalho L; Wang B; Fermin LM; Pomroy WEAIMS: To determine whether evidence for infection with Theileria orientalis (Ikeda) could be identified in samples of commercial red deer (Cervus elaphus), horses, and working farm dogs in New Zealand. METHODS: Blood samples were collected during October and November 2019 from a convenience sample of red deer (n = 57) at slaughter. Equine blood samples (n = 50) were convenience-sampled from those submitted to a veterinary pathology laboratory for routine testing in January 2020. Blood samples, collected for a previous study from a convenience sample of Huntaway dogs (n = 115) from rural regions throughout the North and South Islands of New Zealand between August 2018 and December 2020, were also tested. DNA was extracted and quantitative PCR was used to detect the T. orientalis Ikeda major piroplasm surface protein (MPSP) gene. A standard curve of five serial 10-fold dilutions of a plasmid carrying a fragment of the T. orientalis MPSP gene was used to quantify the number of T. orientalis organisms in the samples. MPSP amplicons obtained by end-point PCR on positive samples were isolated and subjected to DNA sequencing. The resulting sequences were compared to previously published T. orientalis sequences. RESULTS: There were 6/57 (10%) samples positive for T. orientalis Ikeda from the deer and no samples positive for T. orientalis Ikeda from the working dogs or horses. The mean infection intensity for the six PCR-positive deer was 5.1 (min 2.2, max 12.4) T. orientalis Ikeda organisms/µL. CONCLUSIONS AND CLINICAL RELEVANCE: Red deer can potentially sustain low infection intensities of T. orientalis Ikeda and could act as reservoirs of infected ticks. Further studies are needed to determine whether naïve ticks feeding on infected red deer can themselves become infected. ABBREVIATIONS: Cq: Quantification cycle; LOQ: Limits of quantification; MPSP: Major piroplasm surface protein; qPCR: Quantitative polymerase chain reaction.Item CHANGES IN THE LEVELS OF THEILERIA ORIENTALIS IKEDA TYPE INFECTION IN HAEMAPHYSALIS LONGICORNIS NYMPHS OVER A SIX-MONTH PERIOD.(1/09/2021) Zhao Y; Lawrence KE; Minor M; Gedye K; Wang B; Pomroy W; Potter MThis study aimed to investigate whether the infection intensity of Theileria orientalis Ikeda type organisms within Haemaphysalis longicornis larvae and nymph stages fluctuated over 6 mo after feeding as larvae on infected calves in the field. Naïve larvae, hatched from eggs, were fed on infected calves for 5 days while contained within cotton socks glued over the calves' ears. Larvae were first sampled immediately post-feeding and then sampled every 3 wk for 23 wk in total, after molting to nymphs. All larvae and nymphs were tested for T. orientalis Ikeda organisms using quantitative PCR. The qPCR results showed that the infection intensity of Haemaphysalis longicornis larvae and nymphs was not constant over the sampling period, and after initially dropping after molting to nymphs, it then rose with fasting to a maximum at 17 and 23 wk post-feeding. The significant rise in T. orientalis Ikeda organisms observed at 23 wk postfeeding may explain why more severe clinical cases of bovine theileriosis in New Zealand are seen in the spring when nymphs are the predominant instar questing.Item The epidemiology of Theileria orientalis Ikeda type in New Zealand : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Clinical Sciences, Massey University, Palmerston North, New Zealand(Massey University, 2020) Lawrence, KevinThe research presented in this thesis was primarily conducted to document and understand the Theileria orientalis Ikeda type epidemic in New Zealand from 2012 onwards. The thesis summarises the epidemiology of the initial outbreak, presents the results of a prevalence study conducted by the Ministry for Primary Industries in 2013, presents and analyses the common history, haematology and biochemistry changes associated with acute T. orientalis infection, uses different modelling techniques to analyse the spatial-temporal effects on the epidemic, to predict the likely extent of the T. orientalis epidemic and to project the likely effects of global warming on the ecology of Haemaphysalis longicornis, the only competent vector for T. orientalis Ikeda type in New Zealand. In addition, two observational field studies were conducted, the first was a cross-sectional study to investigate the vertical trans-placental transmission of T. orientalis infection from dam to calf and the second was a longitudinal study to investigate the temporal dynamics and effects of T. orientalis infection on haematocrit, production and reproduction in three commercial New Zealand dairy herds.Item The effects of Theileria orientalis Ikeda on bull fertility and libido : a dissertation presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University, Palmerston North, New Zealand(Massey University, 2017) Gibson, Michaela JaneTheileria orientalis is a blood-borne parasite that is prevalent in New Zealand and other countries. The recent emergence (2012) of Ikeda-type orientalis has resulted in an epidemic of bovine anaemia in both dairy and beef cattle herds. The disease is spread by Haemaphylis longnicornis which is prevalent in the majority of the North Island. The Ikeda type has been found to be more pathogenic than previously discovered types such as Chitose and Buffeli. Little is known about how Ikeda-type affects the reproductive performance of bulls. The aim of this experiment was to examine the effects of Theileria Ikeda on the fertility and libido of bulls. A group of 17 bulls were used in the experiment with 10 being infused with Theileria Ikeda-infected blood from two donor cows and the remaining 7 bulls used as controls. All 10 of the treatment bulls were successfully infected with Theileria and became clinically anaemic (Haematocrit below 24) between days 47 and 84 post transfusion. Semen and libido was tested every 2 weeks throughout the experiment. There was no observed change in wave motion score of semen between infected (7.51 ± 0.18) and control (7.08 ± 0.35) treatment groups (P=0.2935) along with no change in forward motion between infected (7.82 ± 0.16) and control (7.64± 0.2610) treatment groups (P=0.5579). The percentage of normal sperm (P=0.0032) was lower in the infected bulls (91.9 ± 0.05) compared to the control group (94.25 ± 0.06) although the density of sperm in an ejaculate (P=0.0044) was higher in infected bulls (1.45x1010 ± 6.88x106 sperm per mL) compared to control bulls (1.14x1010 ± 9.82x106 sperm per ml). Time to first mount (P=0.7374) and gap between first and second mount (P=0.2204) was not significantly different between infected and control groups. The number of mounts was similar between infected (2.33 ± 0.28) and control (2.36 ± 0.17) treatment groups (P= 0.9269) and there was no interaction with time (P=0.2221). However, there was a significant effect of treatment on order of service with infected bulls coming in to the yard later in the herd on day 55 and was statistically significant (P=0.02). In conclusion, changes in fertility occurred in infected bulls but were not drastic enough to indicate a decrease in overall fertility. The only measure of libido affected was order and it is unknown how this would affect pregnancy rates in a herd situation.