Equine piroplasmosis status in the UK: an assessment of laboratory diagnostic submissions and techniques

Abstract

Equine piroplasmosis (EP) has historically been of minor concern to UK equine practitioners, primarily due to a lack of competent tick vectors. However, increased detection of EP tick vector species in the UK has been reported recently. EP screening is not currently required for equine importation, and when combined with recent relaxations in movement regulations, there is an increased risk regarding disease incursion and establishment into the UK. This study evaluated the prevalence of EP by both serology and PCR among 1242 UK equine samples submitted for EP screening between February and December 2016 to the Animal and Plant Health Agency and the Animal Health Trust. Where information was available, 81.5 per cent of submissions were for the purpose of UK export testing, and less than 0.1 per cent for UK importation. Serological prevalence of EP was 8.0 per cent, and parasite DNA was found in 0.8 per cent of samples. A subsequent analysis of PCR sensitivity in archived clinical samples indicated that the proportion of PCR-positive animals is likely to be considerably higher. The authors conclude that the current threat imposed by UK carrier horses is not adequately monitored and further measures are required to improve national biosecurity and prevent endemic disease.

Investigating the presence of equine piroplasmosis in Ireland

“…equi samples detected by PCR were confirmed to be derived from clade E, and of those, three were known to have originated from different countries (Italy, France and Hungary) (32). In the previous UK study (16), three of the ten detected samples were also derived from clade E, further indicating the prevalence of this clade. Unfortunately, the travel history or even domicile of the sampled Irish equines was unavailable, due to data confidentiality, and in the absence of such data this theory cannot be verified.…”

“…The sequences were then subject to genetic analysis, which included comparison to sequences from UK laboratory submissions (16) and field samples from the EP-endemic countries of Morocco, Oman and The Gambia (17) generated using the same nPCR method. Sequence alignments were performed using the MUSCLE method (18) within the AliView software package (19), and nucleotide diversity statistics, including expected heterozygosity (He), nucleotide diversity (π) and haplotype multiplicity, were generated using DnaSP (20).…”

“…This study presents the results of a retrospective analysis of EP-positive samples submitted to the Irish Equine Centre (IEC) between January 2013 and April 2016 and the relevance and implications of these findings are considered. Extracted DNA samples were screened with a Babesia/Theileria 18S SSU rRNA catch-all nested PCR, using published primers and reaction conditions previously used to detect EP parasite DNA in a similar survey of samples submitted to UK diagnostic laboratories (16). PCR amplicons were purified using the QIAquick PCR Purification Kit (Qiagen, Germany) following the manufacturer's recommended protocol prior to commercial Sanger DNA sequencing (Eurofins Genomics, Germany).…”

Emerging Threats to Animals in the United Kingdom by Arthropod-Borne Diseases

“…A threat to equines in the UK is equine piroplasmosis caused by Babesia caballi or Theileria equi infection. Historically, the UK has been considered free of equine piroplasmosis despite the presence of seropositive and pathogen positive horses resident within the country (113) and populations of one of its tick vectors, Dermacentor reticulatus, being present in Wales and southern England (90). Nevertheless, the risk of causative pathogens becoming established within the vector population is evident and could lead to autochthonous transmission in the future.…”

Equine piroplasmosis – the view of a practitioner from an endemic region

“…As highlighted in the paper by Coultous and others, 7 summarised in this issue of Vet Record , EP should be included in the differential diagnosis of horses presenting with hyperthermia, lethargy and haemolysis that live in (or come from) regions at risk of disease. Both parasites can cause severe haemolytic anaemia with fever, icterus, haemoglobinuria and oedema in the distal limbs during acute infection 8 .…”