Introduction

Lyme disease, or Lyme borreliosis, is a bacterial infection which is spread by ticks. These small, eight-legged insects are commonly found in woodlands and grassy areas.¹ 

After a tick bite, the characteristic rash, known as erythema migrans (EM) is observed in more than 70% of people who carry the disease, but it can also be common for people to be unaware that they were bitten.

With Lyme disease, earlier treatment is more effective, because if left unchecked, the bacteria can spread to other organs and cause chronic (long-lasting) infection.²

This may happen to individuals who do not experience the EM rash. Symptoms of Lyme disease, like dizziness, headaches and pain overlap with other conditions, making it difficult to diagnose if the rash is not present. ³

In this article, the current procedures and challenges that come with detecting Lyme disease will be addressed.

Symptoms and initial clinical assessment

Early signs of Lyme disease include an indicative rash and flu-like symptoms:

• Erythema migrans are a raised, red rash that can form in the shape of a bullseye 1-4 weeks after being bitten. It can be warm to the touch, but not itchy or painful⁴
• Chills
• Fever
• Headache
• Tiredness
• Muscle and joint pain⁵

Images of the rash are supplied by the Centres for Disease Control and Prevention (CDC) website, which can be used to check if you have been bitten or not. It also provides examples of skin conditions that can be mistaken for EM  if you would like to compare and confirm.

It is important to have the EM rash physically examined by a clinician, as they will be able to take into account your previous medical history to make a clear diagnosis. Other changes to the skin can have a range of unrelated causes.⁶

As ticks are active year-round outdoors, it is useful for your healthcare provider to know if you have been around woodlands. This allows them to work out if they were exposed to the risk of getting bitten by ticks.

Laboratory tests for Lyme disease

Serological tests

These tests look for the presence of certain antibodies in your blood. Antibodies are proteins that are made to defend your body when it encounters harmful foreign matter, like disease-causing bacteria.

Certain antibodies may act as diagnostic clues that can help guide Lyme disease diagnosis and treatment, especially when the patient does not present erythema migrans. 

Enzyme-linked immunosorbent assay (ELISA)

The enzyme-linked immunosorbent assay, also known as ELISA, detects antibodies made against the bacteria that cause Lyme disease. It does not test for the actual bacteria, known as Borrelia burgdorferi. 

A positive result means that the bacteria was present because antibodies are produced as a response to infection. 

However, it can produce false negatives and false positives. False negatives can be reported when testing is performed too early, meaning that at the time, the body didn’t produce a detectable amount of antibodies against the bacteria. This can also occur in people with a weakened immune system, as they can’t produce enough antibodies. 

Conversely, a false positive signifies that although an antibody was found the patient may not have Lyme disease. This can be caused by other bacterial infections, like syphilis.⁷

Western blot

In the case of a positive result for Lyme disease, western blot (immunoblot) testing is carried out, which will confirm the diagnosis of Lyme disease. It must be noted that the  CDC states  ELISA testing must be carried out before the western blot. 

The western blot validates the presence of specific proteins from a sample and it tests for the same antibodies that the ELISA test looks for in Lyme disease.⁸

Polymerase chain reaction (PCR)

Another test that is used in the diagnosis of Lyme disease is polymerase chain reaction (PCR). Essentially, it allows small fragments of B. burgdorferi DNA to be detected in various samples, such as:

• Blood
• Synovial fluid (a substance that lubricates the joints)
• Cerebrospinal fluid (CSF), is fluid that surrounds your brain and spinal cord

PCR is used to show that the bacteria causing Lyme disease was present in the bodily tissues. 

A pitfall of the method is that it is unable to differentiate between living and dead bacterial DNA, which means it cannot tell if an infection is currently active or has passed.⁹

As testing for Lyme disease has multiple challenges, it is important for new diagnostic methods to be optimised. 

Other emerging diagnostic tests 

Alternative ways of testing for Lyme disease include:

• T-cell-based assays measure the white blood cells’ response to B. burgdorferi¹⁰
• Growing the bacteria in culture¹¹
• Microscopy, to view the presence of B. burgdorferi
• Advanced imaging techniques, like SPECT, MRI or PET scans can be useful in neurological cases¹²
• Bacteriophage therapy – using viruses that infect bacteria. This approach avoids unnecessary damage, as bacteriophages prefer certain host species⁹

Not all of these are used for clinical use but have been applied within labs to study the bacteria in more detail.

Challenges and limitations of current diagnostic methods

Variability in patient responses

Issues that arise from current methods of diagnosing Lyme disease stem from the fact that the bacterial genetics differ between strains. This results in a range of different symptoms, and variance in patient immune response.

Incorrect timing of tests

Furthermore, the timing of tests relative to the infection stage can mislead healthcare providers. When a test is performed too early, it gives you an idea of what was happening at that moment but doesn’t confirm if the results are presently true.

False negatives

This potentially means false negatives can arise in early Lyme disease. For example, as the immune system takes time to adapt to fight B. burgdorferi, it may not produce antibodies in a quantity that is detectable by ELISA.

Cross-reactivity

Cross-reactivity in serological tests contributes to false positives, where antibodies found by ELISA aren’t a reaction to B. burgdorferi, instead these antibodies may have been produced to fight other bacterial or viral infections (Epstein-Barr virus). ¹²

Guidelines and recommendations for lyme disease testing

Improper diagnosis can lead to the incorrect treatment being administered to patients who don’t have Lyme disease.

The GOV website, CDC, and Infectious Diseases Society of America (IDSA) suggest following a two-tiered testing system, using ELISA first, and western blot second. Modified two-tiered testing has become available, with two enzyme immunoassays (EIA) being used in each step.

In the absence of erythema migrans, nonspecific symptoms like joint pain, headaches and dizziness can lead to a false positive. This is because testing may reveal a past infection that has no part in the onset of symptoms not related to Lyme disease. ¹³

Importance of early and accurate diagnosis

Detecting Lyme syndrome as early as possible can help to stop the disease from progressing. Treatment in the early stages is curative, but delayed diagnosis leads to long-term consequences. 

Note that the description of chronic Lyme disease (CLD) is incorrect, as these symptoms may present in people who have no current or past B. burgdorferi infections.¹⁴ They may experience the following:

• Neurological complications, such as visual disturbances, numbness and facial muscle paralysis¹⁵
• Muscle and joint pain 
• Tiredness 

The last two symptoms can occur in patients who have already been treated for Lyme disease. This condition is known as post-treatment Lyme disease syndrome (PTLDS).¹⁴

It is vital for a differential diagnosis to take place in order to rule out other conditions that may be the cause of skin or nonspecific symptoms. This will help patients receive the correct treatment, leading to better outcomes. 

Future directions in lyme disease diagnosis

Advances in diagnostic technology, such as multiplex testing, improve serological assays by detecting Lyme disease with higher sensitivity.¹⁶

Biomarkers are certain molecules which allow scientists to identify specific traits and research is being carried out to find a biomarker that indicates a current B. burgdorferi infection.¹⁷

A personalised medical approach to post-treatment Lyme disease syndrome may be essential for patients with the disease. PTLDS symptoms come from a range of different causes, meaning each individual needs a tailored treatment regimen to effectively recover. ¹⁸

Current research seeks to uncover more about the bacterial genome to guide treatment and diagnostic tools, as well as uncover the pathogenesis of PTLDS. 

Inflammatory pathways and patient immune responses to PTLDS are still being investigated, with scientists trying to map out how the disease works. 

Treatment is also a popular area of interest, with antibiotics being studied for their efficacy.¹⁹

Summary

Lyme disease is a tick-borne disease caused by bacteria which resolves well if treated early. However, diagnosing the condition is difficult as it causes different patient reactions. Additionally, the testing methods used have the potential to provide inaccurate results.

This poses an issue for patients, as they may not receive the proper care needed. If left untreated, Lyme disease can have neurological complications, as well as a range of other symptoms that lower quality of life.

Ongoing research aims to provide more information on how we can effectively diagnose Lyme disease, by improving tests that are already in place.