Ikeda infection detected in red deer but not dogs or horses in New Zealand.

Abstract

AIMS: To determine whether evidence for infection with(Ikeda) could be identified in samples of commercial red deer, 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 theIkeda major piroplasm surface protein (MPSP) gene. A standard curve of five serial 10-fold dilutions of a plasmid carrying a fragment of theMPSP gene was used to quantify the number oforganisms 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 publishedsequences. RESULTS: There were 6/57 (10%) samples positive forIkeda from the deer and no samples positive forIkeda 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)Ikeda organisms/µL. CONCLUSIONS AND CLINICAL RELEVANCE: Red deer can potentially sustain low infection intensities ofIkeda 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.