A Rutgers researcher who wanted to help a sick horse developed a highly sensitive DNA test that might be used to diagnose hard-to-find diseases in people like Lyme disease.
According to a study that was published in the Journal of Veterinary Diagnostic Investigation, a team from Cornell University School of Veterinary Medicine was able to diagnose Neurologic Lyme disease in a sick 11-year-old Swedish Warmblood mare using a special DNA test developed by Steven Schutzer, a professor of medicine at Rutgers New Jersey Medical School.
Although Lyme disease was suspected, the disease’s causative agent, the corkscrew-shaped bacterium Borrelia burgdorferi, was missed by a routine PCR test. Early diagnosis is crucial for Lyme disease therapy, as it is for the majority of disorders.
“Early diagnosis leads to immediate treatment,” Schutzer said. “And, naturally, that gives the best chance for a cure.”
The infection was found in a sample of the horse’s spinal fluid by the Schutzer team’s very sensitive “genomic hybrid capture assay,” which enabled it to be diagnosed and successfully treated. The test functions by first isolating DNA from the disease-causing bacteria with precision.
“The method is like having a special, specific ‘fishhook’ that only grabs Borrelia DNA and not the DNA of other microbes, nor the DNA of the host (animal or human),” Schutzer said. “Detecting DNA of the disease is a direct test, meaning we know you have active disease if it’s circulating in the blood or spinal fluid.”
According to the Centers for Disease Control and Prevention (CDC), Lyme disease is the most prevalent vector-borne disease in the United States. In people, a typical skin rash, fever, headache, and exhaustion may or may not appear. If left untreated, the infection may spread to the heart, joints, and neurological system.
The diagnosis of Lyme neuroborreliosis (Neurologic Lyme disease) in horses is rarely confirmed antemortem and has frustrated veterinarians for years. This is a very promising technique. Focused treatment against B. burgdorferi administered in this case resulted in the horse’s complete athletic recovery.
Thomas Divers
Horses are accidental, dead-end hosts for B. burgdorferi, much like humans, which means that the hosts have the illness but do not spread it to others. Not all infected horses exhibit clinical Lyme disease symptoms. Symptoms may include low-grade fever, lameness, and persistent weight loss.
Usually, when a Lyme disease infection is suspected, antibody testing are conducted. An antibody test and a PCR test of the mare in the study’s case study failed to detect an infection.
Only Schutzer’s sophisticated test could identify the illness. Horses that have Lyme disease may experience long-term problems, such as harm to their nervous system, joints, skin, or even vision.
“The diagnosis of Lyme neuroborreliosis (Neurologic Lyme disease) in horses is rarely confirmed antemortem and has frustrated veterinarians for years,” said Thomas Divers, the veterinarian who led the equine team on the paper and who is a professor of medicine and co-chief of the Section of Large Animal Medicine at Cornell University’s College of Veterinary Medicine in New York. “This is a very promising technique. Focused treatment against B. burgdorferi administered in this case resulted in the horse’s complete athletic recovery.”
When compared to other diseases, such as Lyme disease, the bacteria slowly reproduce within a host, producing significantly less numbers and making detection more challenging. This is in contrast to many infections, such as COVID-19 and strep throat, which attack humans with many numbers of pathogens.
As a specialist in Lyme and other tick-borne diseases, Schutzer has been attempting to develop methods to more effectively identify illnesses that have what he refers to as “low copy counts” of a pathogen.
Each year, approximately 476,000 human cases of Lyme disease are documented, according to the CDC. The majority of Lyme disease cases in the United States are caused by the black-legged tick, sometimes referred to as the deer tick. Both its population and geographic distribution appear to be growing.
Other scientists on the study included Claire Fraser and Emmanuel Mongodin of the Institute of Genome Sciences at the University of Maryland School of Medicine; Christopher Miller of Miller and Associates Equine Practice in Brewster, N.Y.; Rodney Belgrave of Mid-Atlantic Equine Hospital in Ringoes, N.J.; and Rachel Gardner of B.W. Furlong and Associates in Oldwick, N.J.
