Can Lyme Disease Be Detected by a Blood Test?

Lyme disease can be detected by tests that look for antibodies in the blood. Learn more about Lyme disease testing, stages, and symptoms

Lyme disease can be detected by tests that look for antibodies in the blood or in the fluid from the joints or spine. However, antibodies can take 4-6 weeks to be detected in a blood test after becoming infected. 

Borrelia burgdorferi (B. burgdorferi) is the bacterium that causes Lyme disease, and there are two tests that can detect whether you have developed antibodies in response to it:

• Enzyme-linked immunosorbent assay (ELISA): Detects antibodies against B. burgdorferi and is the most commonly used test.
  • Although this test may not give a positive result in the early stages of Lyme disease, doctors may make a diagnosis if the rash is distinctive enough in patients who reside in Lyme disease-infested areas. 
  • However, this test is seldom used as the main basis for diagnosis because it can sometimes produce false-positive results.
• Western blot test: Detects antibodies against B. burgdorferi and can confirm ELISA test results.

In the first few weeks of infection, especially when a patient has a rash of erythema migrans, diagnostic test results will be negative. Some people who take a course of antibiotics in the early stages of the disease may have a negative blood test result because the concentration of antibodies are too low.

What is Lyme disease?

Lyme disease is a bacterial infection that is caused by tick bites. It causes rash and, if left untreated, can lead to more serious problems. 

B. burgdorferi is carried by the black-legged tick, also known as deer tick, although not all species of ticks carry these bacteria. Nymphs, which are small immature ticks roughly the size of a pinhead, pick up bacteria when they feed on small B. burgdorferi–infected animals such as mice. They can then transmit Lyme disease when they bite humans.

What are the stages of Lyme disease?

Lyme disease has many symptoms that are similar to those of other disorders, thus making diagnosis difficult. Signs may vary depending on the stage of the disease:

• Stage I: Early localized
  • This is the initial stage called erythema migrans.
  • Bacteria have not spread all over the body yet.
  • On physical examination, your doctor may note a rash near the tick bite.
  • The rash typically appears a couple weeks after being bitten.
• Stage II: Early disseminated
  • Bacteria has begun to spread throughout the body by traveling through the bloodstream.
  • Symptoms such as fever and pain appear during this stage.
  • Bacteria may eventually start to affect the nervous system and heart.
• Stage III: Late disseminated
  • This stage begins several weeks after the initial tick bite.
  • In this stage, the bacteria has spread to every part of the body.
  • Symptoms involving the joints or neurological system are common.

It is important to understand each stage of Lyme disease because blood testing is not equally helpful at each level. Blood testing is often ineffective in the early stages because antibodies have not had enough time to form.

This is why blood tests alone are insufficient to diagnose Lyme disease. Physical examination, symptoms, and the possibility of tick exposure are essential for proper diagnosis.

Bowel regularity means a bowel movement every day.
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What are the symptoms of Lyme disease?

The first symptom of Lyme disease is usually a circular, red rash (erythema migrans) at the site of the tick bite, sometimes called a bullseye rash. This generally emerges within 4 weeks of getting bitten. Other symptoms may include:

• Fever and chills
• Headache
• Malaise (feeling ill)
• Pain and swelling in the joints
• Muscle weakness and pain
• Neck stiffness
• Weakness or paralysis in the facial muscles
• Pain and numbness due to nerve damage
• Chest pain
• Palpitations
• Breathlessness
• Sleeping disorders
• Vision changes
• Cognition impairment

What is the treatment for Lyme disease?

Your doctor will make decisions about a treatment regimen after taking into consideration factors such as your age, medical history, underlying health concerns, or allergies.

Patients with early stage Lyme disease recover completely with appropriate antibiotic therapy. 

However, if the disease is detected in later stages, recovery may take longer and patients will need longer courses of antibiotics. In some cases, intravenous administration of antibiotics is required. Antibiotics such as amoxicillin, doxycycline, or cephalosporins are generally used.