New research confirms Strangles blood test accuracy

New research conducted by the Animal Health Trust (AHT) and funded by The Horse Trust has confirmed that its Strangles blood test is significantly more accurate for measuring a horse’s immune response to the bacteria behind the disease, Streptococcus equi, when compared to another test available on the market.

The research, detailed in a recently published paper compared the effectiveness of the SeM-based blood test marketed by IDvet, with the blood test developed by the AHT.

Both blood tests aim to detect anti-Streptococcus equi antibodies in order to assist with the identification of apparently healthy, yet persistently infected carriers of Strangles. Further tests are required to confirm that the horse is infectious; however the immune response test is an important first stage in the detection and treatment of Strangles. If infected horses are identified quickly and efficiently, then the spread of outbreaks can be limited, and in some cases, prevented.

Dr Andrew Waller, Head of Bacteriology at the AHT, said: “The AHT’s blood test for Strangles enables vets to be more confident in identifying horses that may be infected with Streptococcus equi.

“Seropositive horses that are subsequently confirmed as infected with Streptococcus equi can be treated, the infection eradicated and future outbreaks prevented. Although these are new results, we have been using this blood test in the UK since 2008 and know that it works – it really does lower the risk of Strangles reoccurring.”

Strangles remains the most frequently diagnosed, infectious disease in horses worldwide, with over 600 outbreaks identified each year in the UK alone. The AHT has been researching ways to combat Strangles since 1990.

In 2008, the AHT launched the first blood test to detect anti-Streptococcus equi antibodies in blood serum within 48 hours. The launch of this test was made possible due to substantial research undertaken by the AHT and Wellcome Trust Sanger Institute and funded by The Horse Trust, to successfully sequence the Streptococcus equi genome. This led to the development of a robust assay with both high sensitivity and specificity, which accurately measures horses’ immune response to the disease.

The AHT is currently developing an effective vaccine against the disease, which when used alongside the blood test can differentiate infected from vaccinated animals (so-called DIVA). The AHT is also working to make its blood test available in laboratories outside of the UK, in order to help vets and horse owners around the world to combat Strangles more efficiently.

Jeanette Allen, Chief Executive of the Horse Trust, said: ”The Horse Trust has been proud to support the highly important Strangles research work carried out by the team at the Animal Health Trust. Strangles is a major welfare concern in the UK and we are delighted that the genome sequence project has paved the way for the development of this highly effective blood test.

“We believe the blood test will significantly improve the ability of vets to control Strangles and will have real impact on equine welfare. We encourage all practitioners to familiarise themselves with this test and to incorporate it into their disease management plans.”

The full research paper ‘Combining two serological assays optimises sensitivity and specificity for the identification of Streptococcus equi subsp. equi exposure’ by Robinson,C., et al is published in The Veterinary Journal and is available at: www.sciencedirect.com/science/article/pii/S1090023313000567.