New Test Can Differentiate Between Tick-borne Illnesses

Time is of the essence in diagnosing and treating Lyme disease and other tick-borne illnesses. Fortunately, one new test may be able to help. A report on the test was published in the journal Science Translational Medicine.

Ticks and the diseases they carry are on the rise. One 2016 study found deer ticks—the species that carries Lyme disease—in more than half of the counties in the United States.

The two most common tick-borne illnesses in the U.S. are Lyme disease and southern tick-associated rash illness (STARI). Although their initial symptoms can be the same, they’re caused by different pathogens; Lyme disease comes from infection with the bacterium Borrelia burgdorferi. We don’t know what causes STARI.

"It is extremely important to be able to tell a patient they have Lyme disease as early as possible so they can be treated as quickly as possible," microbiologist and first author Claudia Molins of the CDC said in a statement. "Most Lyme disease infections are successfully treated with a two- to three-week course of oral antibiotics." Infections that aren't treated can lead to fevers, facial paralysis, heart palpitations, nerve pain, arthritis, short-term memory loss, and inflammation of the brain and spinal cord.

But to date, scientists have yet to create an accurate, consistent early test for Lyme disease, which means people must often wait until they’re very ill. And it’s hard to test for the STARI pathogen when we don’t know what it is.

One team of researchers led by experts at Colorado State University was determined to find a better way. They realized that, rather than looking for pathogens, they could look at the way a person’s body responded to the pathogens.

They analyzed blood samples from patients with both early-stage Lyme disease and STARI. Their results showed that while all patients’ immune systems had mounted a response, the nature of that response was different.

"We have found that all of these infections and diseases are associated with an inflammatory response, but the alteration of the immune response, and the metabolic profiles aren't all the same," senior author John Belisle of CSU said.

Two distinct profiles emerged. The team had found physical evidence, or biomarkers, for each illness: a way to tell one disease from another.

Belisle notes that there’s still plenty of work to do.

"The focus of our efforts is to develop a test that has a much greater sensitivity, and maintains that same level of specificity," Belisle said. "We don't want people to receive unnecessary treatment if they don't have Lyme disease, but we want to identify those who have the disease as quickly as possible."