New Method for Lyme Disease Diagnostics

Horse owners will now be able to know the results of a Lyme disease test within minutes instead of having to wait for as long as a week. A new test, the Snap 3Dx assay, to confirm Borrelia burgdorferi, the causative bacterial agent for Lyme disease, has been developed by IDEXX Laboratories. Reported equine infections in northeastern U.S. have been dramatically increasing, with nearly 50% of adult horses being infected or having been infected at one point. Other areas with a high rate of Lyme disease include the Midwest, Texas, and California.

Adult horses can be infected by the bite of infected deer ticks that are in the larval, nymph, or adult stages. Ticks feed by inserting their mouths into the skin of the host and slowly taking in blood;  B. burgdorferi is most likely to be transmitted after an infected tick has fed for more than two days. Clinical disease is characterized by lameness, stiffness, joint swelling, lethargy, fever, weight loss, uveitis, and potentially with neurologic disease and foal mortality.

The SNAP 3Dx assay had previously only been used on dogs in a clinical setting to determine the status of the disease. In a study by IDEXX Laboratories to determine the test’s usefulness in horses, 164 horse serum samples were tested for Lyme disease by both the SNAP 3Dx assay and the Lyme Western Blot Assay (the most commonly used test for detecting Lyme disease in equines). Of the 164 samples, 109 tested positive when using the SNAP 3Dx assay, while 106 samples tested positive with the Western Blot kit. The three samples that did not test positive using the Lyme Western Blot Assay were checked with an immunofluorescence assay, where B. burgdorferi antibodies in the blood would appear fluorescent if an infection was present.  The three samples did test positive for Lyme disease, proving that the SNAP 3Dx assay shows 100% sensitivity to B. burgdorferi antibodies and is clinically effective for testing horses for Lyme disease.

The SNAP 3Dx assay will benefit horse owners because this test provides a convenient, fast way to determine the infection status of horses thought to have contracted Lyme disease. The Lyme Western Blot Assay requires four days for the blood test to run and must be sent to a specialized laboratory, which also poses the risk that the serum sample might be lost or damaged in transport.  The SNAP 3Dx assay only requires eight minutes for the test to run and can be used in a veterinary office, according to IDEXX representative Sharon Collin.

About the Author

Marcella M. Reca Zipp, MS

Marcella Reca Zipp, M.S., is a former staff writer for The Horse. She is completing her doctorate in Environmental Education and researching adolescent relationships with horses and nature. She lives with her family, senior horse, and flock of chickens on an island in the Chain O'Lakes.

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