Validation of an in-clinic enzyme-linked immunosorbent assay kit for diagnosis of Borrelia burgdorferi infection in horses.

This research article discusses the validation of a quick in-clinic diagnostic test kit for horses suspected to be infected by Borrelia burgdorferi, the bacterium responsible for Lyme disease. The research shows that although the test has a moderate sensitivity, which may result in occasional false negatives, it presents a speedy, inexpensive alternative to the traditional lab-based testing methods.

Study Design

• The researchers evaluated an in-clinic C6 ELISA SNAP kit meant for dogs on horses using serum from horses experimentally infected with Borrelia burgdorferi, the bacterium transmitted by ticks to cause Lyme disease.
• They drew serum samples from two studies. In the first study, they exposed seven ponies to ticks infected with B. burgdorferi and kept four ponies as uninfected controls. They collected serum samples every two months for nine months.
• In the second study, they exposed sixteen ponies to B. burgdorferi-infected ticks and, after confirming the infection through skin culture, polymerase chain reaction (PCR), and serology, divided the ponies into four groups. These groups received either doxycycline, tetracycline, ceftiofur, or no treatment. Here, they collected serum samples before and after antibiotic treatments monthly for eleven months.

Test Procedure

• For this study, selected samples (n = 220) from both studies were tested using the IDEXX SNAP Heartworm Ab/Borrelia burgdorferi Ab/Ehrlichia canis Ab Test Kits.
• The samples included ones taken before infection, from several points after infection, and after antibiotic treatments.

Results

• The results of the confirmed positive or negative samples were used to determine the sensitivity (ability to correctly identify positive cases) and specificity (ability to correctly identify negative cases) of the assay.
• The test kits showed modest sensitivity (63%) and very high specificity (100%) for horses that had recently been infected with B. burgdorferi.

Conclusion

• The validation of this test provides a faster, inexpensive, in-clinic method for equine practitioners to confirm B. burgdorferi infection in horses.
• The moderate sensitivity of the test, however, indicates that there may be a moderate chance of receiving a false negative result.