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Diagnostics

Lyme disease tests on the horizon

New diagnostic approaches bring hope for patients with debilitating tick-borne illnesses

by Britt E. Erickson
September 2, 2018 | APPEARED IN VOLUME 96, ISSUE 35

 

09635-feature2-Lymebacteriacxd.jpg
Credit: Janice Haney Carr/CDC
Bacteria that cause Lyme disease, B. burgdorferi, are challenging to detect directly because they reproduce slowly and therefore occur in small numbers. The average length of the bacterium is 20–30 µm.

When Hannah Wright graduated high school 10 years ago, she dreamed of attending law school. But within the first few months of college at the University of California, Irvine, she began feeling tired and foggy minded. She developed a stiff neck and intermittent blurry vision.

At the time, Wright was in a sorority, served as vice president of a mock trial team, and traveled a lot. So she attributed the symptoms to living in a new environment and being under a lot of stress. “I just thought it was a life change that was causing all of my fatigue,” she says.

Lyme disease by the numbers

 

3 million
blood specimens tested for Lyme disease each year in the U.S.

 


300,000
new cases of Lyme disease estimated each year in the U.S.

 


10 to 20%

Lyme disease patients that continue to experience symptoms after antibiotic treatment


7

new germs spread by tick bites discovered from 2004 to 2016 in the U.S.

Over the next four years, Wright’s health and grades went up and down like a roller coaster. “I was in and out of the hospital about seven or eight times during college,” she recalls. Her doctors told her that she needed to learn better coping mechanisms. They attributed her stiff neck to having a poor ergonomic setup while using a laptop and blamed her vision problems on staring at electronic screens.

“I would be on the dean’s list one quarter and on academic probation the next,” Wright says. She ended up missing final exams during her last quarter after blacking out in the library with a horrific headache. “I felt like my brain was about to erupt like a volcano,” she says. Still, doctors could not find anything wrong with her.

Wright sought help from a therapist for depression and anxiety. In 2016, after spending a week in a mental hospital and having episodes of zombielike behavior, doctors in California finally gave her a test that led to a diagnosis: Lyme disease. Caused by the bacterium Borrelia burgdorferi, Lyme disease is the most common tick-borne illness in the U.S.

Wright was treated with antibiotics, and most of her symptoms disappeared. She has since moved to New York, where she now works as an advocate for the Global Lyme Alliance (GLA), a group that educates people about Lyme disease and supports the development of new diagnostics and treatments.

Lyme disease and other tick-borne illnesses are on the rise. The number of cases of Lyme disease reported to the U.S. Centers for Disease Control & Prevention has grown from about 20,000 in 2006 to more than 30,000 in 2016. But CDC acknowledges that the true number of new Lyme disease cases each year in the U.S. is likely to be about 300,000, because many people don’t report their illness or have gotten a false negative test result.

Top 3 ticks in the U.S.

The ticks that most commonly bite humans in the U.S., and the pathogens (and diseases) they transmit

 

Black-legged or deer tick (Ixodes scapularis)

Location: Eastern U.S.

Transmits: Borrelia burgdorferi and B. mayonii (which cause Lyme disease), Anaplasma phagocytophilum (anaplasmosis), B. miyamotoi (B. miyamotoi disease), Ehrlichia muris eauclairensis (ehrlichiosis), Babesia microti (babesiosis), and Powassan virus (Powassan virus disease)

Lone star tick (Amblyomma americanum)

Location: Eastern U.S., but more common in the South

Transmits: Ehrlichia chaffeensis and E. ewingii (human ehrlichiosis), Francisella tularensis (tularemia), Heartland virus (Heartland virus disease), Bourbon virus (Bourbon virus disease), pathogen that causes southern tick-associated rash illness, and galactose-α-1,3-galactose (allergic reactions to red meat in some people)

American dog tick (Dermacentor variabilis)

Location: East of the Rocky Mountains; limited areas on the Pacific coast

Transmits: Francisella tularensis (tularemia) and Rickettsia rickettsii (Rocky Mountain spotted fever)

Source: CDC

Ticks and the diseases they spread are a growing problem because there are “just more animals to feed on,” says Rafal Tokarz, a researcher and expert in tick-borne diseases at Columbia University Mailman School of Public Health, or because climate change is expanding the territory in which ticks live. Regardless of the reason, the increase in illnesses has led to demand for better diagnostics.

As Wright’s story illustrates, the symptoms of tick-borne diseases don’t always point directly to a clear diagnosis. Infectious-disease experts predict that the prevalence of Lyme disease and other tick-borne illnesses will continue to grow substantially, and management of the diseases will be seriously hampered until improved diagnostics make their way into clinics (N. Engl. J. Med. 2018, DOI: 10.1056/nejmp1807870).

The National Institutes of Health spent about $22 million last year to support basic research related to Lyme disease. About one-fifth of that money supported the development of new diagnostics, says Maliha Ilias, a Lyme disease program officer at NIH’s National Institute of Allergy & Infectious Diseases (NIAID). Other organizations are also putting money into diagnostics for Lyme and other tick-borne diseases to supplement what they say is insufficient government funding.

“We understand the need for a sensitive, specific, rapid point-of-care diagnostic for Lyme disease,” Ilias says. “Not just to detect Lyme disease early but to detect active infections so you can assess whether the treatment was effective.”

Wright, who still has tremors in her hand and stutters when she gets tired, could benefit from such a test. She believes her ongoing symptoms are caused by posttreatment Lyme disease syndrome, a condition that affects about 10–20% of Lyme disease patients after they have been treated. But her doctor in New York is not convinced that she has or ever had Lyme disease. The doctor who originally diagnosed her in California—where Lyme disease is rare—and her doctor in New York interpret her test results differently.

Subjective interpretation is a common problem with the recommended test for Lyme disease. The test involves an enzyme-linked immunosorbent assay or immunofluorescent assay, followed by a Western blot if the first test is positive. The Western blot produces a set of bands, each representing antibodies in a person’s blood produced against a particular B. burgdorferi antigen. Interpretation of the results depends on whether the investigator sees a band. Doctors typically agree that five bands are needed to be considered positive for Lyme disease.

Because antibodies linger after a pathogen has cleared, the test cannot differentiate between a past infection and an active one. Clinicians and patients would like to have tests that indicate whether people like Wright, who may have posttreatment Lyme disease syndrome, are still infected with B. burgdorferi or whether their symptoms are caused by an immune response triggered by a former infection—situations that require different treatments.

The test is also not good for early diagnosis because it takes several weeks for a person’s immune system to produce antibodies against B. burgdorferi. Lyme disease is most treatable with antibiotics during the first few weeks of infection. The longer people go untreated, the more likely they will experience severe symptoms.

NIH is funding several researchers to develop non-antibody-based approaches to address these limitations.

For example, a group of researchers led by John Belisle, a microbiology professor at Colorado State University, is using a metabolomic approach to identify small-molecule biomarkers in blood and urine samples to help detect early Lyme disease. The team reported last year that it had discovered a metabolic biosignature in blood that can be used to discriminate between early Lyme disease and a similar illness called southern tick-associated rash illness (STARI) (Sci. Transl. Med. 2017, DOI: 10.1126/scitranslmed.aal2717). The two diseases have nearly identical symptoms—fever, chills, headache, fatigue, muscle and joint pain, swollen lymph nodes, and a bull’s-eye rash. Belisle and colleagues also recently published data that demonstrate urine metabolites alone can be used as a biomarker for detecting early Lyme disease (Sci. Rep. 2018, DOI: 10.1038/s41598-018-29713-y).

Another group is aiming to detect Lyme disease with an immunoassay based on cytokines, small proteins that affect immune response to pathogens. Paul Arnaboldi, a professor at New York Medical College and lead research scientist at peptide synthesis company Biopeptides, is leading the project.

When a person encounters B. burgdorferi antigens, these peptides stimulate the release of the cytokine interferon γ (IFNγ) from immune cells called T cells. Unlike antibodies, which can stay elevated for years after an infection has cleared, levels of IFNγ rapidly fall after a pathogen such as B. burgdorferi is eliminated.

Arnaboldi and his team first identified unique peptides derived from antigens expressed by B. burgdorferi. Using those, they showed that T-cell activity can be correlated with active Lyme disease and that IFNγ secretion is significantly reduced 60 days after antibiotic treatment. The researchers are now optimizing the assay by searching for additional peptides that stimulate release of IFNγ in conjunction with B. burgdorferi infection. They are also testing the specificity of the assay using samples from people with illnesses other than Lyme disease that may produce a similar immune response.

The currently recommended blood test for Lyme disease detects only exposure to B. burgdorferi. Clinicians and patients, however, would be better served by diagnostics that differentiate among Lyme and other diseases, particularly other tick-borne diseases. Ticks often carry more than one disease-causing agent that produces similar symptoms to Lyme disease, but some of those pathogens are viruses or parasites that are not effectively treated with antibiotics. It is important to know what pathogen people have been exposed to so that they can be properly treated, Tokarz notes.

“I like to remind people that Lyme disease is the most problematic and most frequent tick-borne disease, but there are others that people should be aware of, especially if they live in areas where there are a lot of ticks,” Tokarz says.

For example, the black-legged tick, also called the deer tick (Ixodes scapularis), which is found across the eastern U.S., can transmit pathogens that cause anaplasmosis, relapsing fever, ehrlichiosis, babesiosis, and Powassan virus disease, as well as Lyme disease.

The lone star tick, Amblyomma americanum, is now similarly found throughout the eastern U.S. It used to be more common in the south but has expanded north and west in recent years. Distinguished by a small white spot on its back, the lone star tick can transmit pathogens that cause ehrlichiosis, tularemia, Heartland virus disease, Bourbon virus disease, and STARI. The lone star tick can also induce an allergic reaction to red meat in some people.

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Tokarz and colleagues at Columbia University are collaborating with researchers from CDC, NIAID, Roche Sequencing, Farmingdale State College, and Stony Brook University to develop a single blood test that can detect whether a person has any of eight common tick-borne diseases, Lyme included. Earlier this year, the team published initial results from its so-called Tick-Borne Disease Serochip (Sci. Rep. 2018, DOI: 10.1038/s41598-018-21349-2).

The device is a glass slide with 10 to 16 wells, with each well representing a separate test. The wells contain about 170,000 linear peptides with 12 amino acids each from antigens discovered in the eight tick-borne pathogens. If a blood sample contains antibodies to a particular pathogen, the antibodies will bind to the peptide fragments specific to that pathogen. With the help of a fluorescent tag, the researchers detect the interaction by fluorescence intensity using an array scanner.

The researchers have shown that the chip-based device can differentiate between various tick-borne diseases with high sensitivity. Importantly, as new tick-borne pathogens emerge, they can be added to the test. It takes about a month to add a new tick-borne pathogen to the serochip, Tokarz says. The team is currently streamlining the device, “making it smaller, more efficient, and most importantly, cost effective in order to bring it into a clinical lab,” Tokarz tells C&EN.

Overall, efforts to develop new diagnostics for Lyme disease are still at the basic research stage, NIAID’s Ilias says. “We are not sure what the ultimate product will look like.” It could be several more years before the U.S. Food & Drug Administration approves any new Lyme tests.

FDA did, however, in July grant Ceres Nanosciences, a Virginia-based company focused on developing diagnostics using nanotechnology, breakthrough device designation for its point-of-care Nanotrap Lyme Antigen Test System. That designation is intended to reduce the time and cost from development to FDA approval.

Ceres received funding from the Bill & Melinda Gates Foundation to help with commercialization of the test, which is designed for use in a clinic or doctor’s office. The test involves proprietary nanoparticles that bind to the outer surface protein A (OspA) antigen expressed on the surface of B. burgdorferi. The team reported in 2015 that it found OspA in the urine of 151 people suspected to have early-stage or recurrent Lyme disease (J. Transl. Med.,DOI: 10.1186/s12967-015-0701-z). The researchers did not find any of the protein in the urine of 117 healthy controls.

GLA, the organization Wright now works for, is also supporting efforts to get improved diagnostics for Lyme disease into clinical practice. Last year, the group partnered with New York-based biotech company Ionica Sciences to accelerate the development of a test for Lyme disease called IonLyme.

The test detects the presence of B. burgdorferi proteins via surface-enhanced Raman scattering spectroscopy. It allows earlier detection of Lyme disease than the current standard antibody-based tests and can be rapidly modified to detect other tick-borne diseases.

“Without the support of GLA, IonLyme would have remained a good idea on a whiteboard,” Omar Green, CEO of Ionica, said in a statement when the partnership with GLA was announced last year. Private funding “is more important than ever,” says Rona Cherry, public relations liaison for GLA. Government funding is extremely limited, she says. NIH spends less money on Lyme disease than West Nile virus and other diseases with fewer numbers of people affected, Cherry adds.

In fact, when adjusted for inflation, NIH funding for Lyme disease research has been decreasing over the past decade even as the number of tick-borne infections has increased. To date, GLA has provided $10 million in support of Lyme disease research.

It remains to be seen whether any new tests for Lyme disease will make it into doctors’ offices. Wright hopes that eventually an over-the-counter test for Lyme disease will be sold directly to consumers. People will be able to take the test at home and contact their doctor if they are positive, she predicts.

Because of her health struggles, Wright did not go to law school. “I thought I would be too sick,” she says. “There is something in the Lyme community called flare fear. I was always worried that if I was under copious amounts of stress that it would trigger it.”

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Comments
Kat (September 10, 2018 8:22 PM)
Wow! Scary stuff. I understand that co-infections can be worse than Lyme. Thank you for useful I formation that will hopefully halt this plague in its tracks
Tracey N. (September 14, 2018 3:01 PM)
Thank you very much for this article, a much-needed ray of hope in a decade+ long struggle with this horrible illness which has robbed me of so much, including my confidence in our medical system. I continue to pray for a future without so many, many people suffering even after correct diagnosis. I have far too many friends and acquaintances who also lost too many years (and in some cases, their lives) to this devastating disease.

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