A UConn-led study found antibodies to Leptospira bacteria in 244 of 397 horse blood samples from Connecticut, evidence of immune exposure that does not establish that those horses had active infections.
The peer-reviewed study in BMC Veterinary Research reported a positive-test rate of 61.5%. UConn drew attention to the findings in an Oct. 20 research announcement.
Leptospira can cause leptospirosis, a bacterial disease affecting animals and people. In horses, illness can include reproductive problems and eye inflammation. An antibody test measures the immune system's response, rather than directly finding living bacteria.
The test cannot separate antibodies caused by natural exposure from antibodies produced after vaccination. After the researchers removed results for Pomona, the group of bacteria covered by the U.S. horse vaccine, 204 samples, or 51.4%, remained positive.
That calculation reduces one possible source of vaccination bias; it still does not identify which animals were infected, shedding bacteria or ill when sampled.
The samples came from the Connecticut Veterinary Medical Diagnostic Laboratory and had been submitted for other disease testing, according to UConn. They were not a random survey of every horse in the state, so the percentage should not be treated as a statewide infection rate.
Camila Hamond and Elsio Augusto Wunder Jr. were among the researchers leading the work. The paper calls for studies that directly isolate and identify the bacteria to clarify horses' role in transmission.
The study was published Aug. 1 in an early accepted version that the publisher says may receive further edits.