The More You Know About Lyme Disease the Easier It Is to Code

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  • July 31, 2019
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The More You Know About Lyme Disease the Easier It Is to Code

The pesky illness can be diagnosed properly by knowing the signs and symptoms and detecting it with pathology.

Lyme disease is a common vector-borne illness in the United States, with more than 300,000 cases each year, according to the Centers for Disease Control and Prevention (CDC). The most prevalent areas for outbreaks are in the Northeast and Mid-Atlantic regions, with Pennsylvania having the most confirmed cases of Lyme disease in the country since 2000, according to PA Penn Live news. With so many confirmed cases, it’s important to learn more about this dangerous disease’s signs and symptoms, screening, pathology, diagnosis coding, and treatment.

What Causes Lyme Disease?

The causative agent of Lyme disease is the bacterium Borrelia burgdorferi (B. burgdorferi), which belongs to a group of bacteria called spirochetes. B. burgdorferi has a unique morphology that includes a spiral or wavelike body and flagella, as shown in Figure 1.
This bacterium uses the tick as a vector (transmitter). In stage 1, adult female ticks drop off the host to lay eggs. The eggs hatch into six-legged larvae, which attach to and feed on the first host, which may become infected. Once the larvae molt into nymphs, they leave the first host. It’s at this point the infected nymphs can feed, in lieu of a second host, on humans, who also may become infected with the disease. The nymphs molt into adults after leaving the second host. Adult ticks attach to a third host, which can include humans, transmitting B. burgdorferi. For a better understanding, see Figure 2 for the life cycle stages.
Life cycle stages

Signs and Symptoms of Lyme Disease

Lyme disease is diagnosed based on signs and symptoms, as well as history of possible exposure to infected black-legged ticks.
Untreated, Lyme disease can produce a wide range of symptoms and, depending on the stage of infection, can spread to:

  • Joints – ICD-10-CM code A69.23 Arthritis due to Lyme disease
  • Heart – ICD-10-CM code A69.29 Other conditions associated with Lyme disease
  • Nervous system – ICD-10-CM code A69.22 Other neurologic disorders in Lyme disease

Signs and symptoms occurring within three to 30 days post tick bite, include:

  • Fever (R50.9 Fever, unspecified)
  • Chills (R68.83 Chills (without fever))
  • Headache (R51 Headache)
  • Fatigue (R53.83 Other fatigue)
  • Muscle and joint ache (M25.50 Pain in unspecified joint)
  • Swollen lymph nodes (R59.9 Enlarged lymph nodes, unspecified)

The bull’s-eye, or target rash, is a hallmark of Lyme disease infection, as shown in Figure 3.

Bull's-eye rash

Classic Lyme disease bull’s-eye target rash.

Later signs and symptoms include:

  • Severe headaches (R51)
  • Additional rashes (L30.9 Dermatitis, unspecified)
  • Arthritis (A69.23)
  • Facial palsy (R29.810 Facial weakness)
  • Intermittent pain in tendons, muscles, joints, and bones (M25.50)
  • Heart palpitation (R00.2 Palpitations)
  • Dizziness (R42 Dizziness and giddiness)
  • Inflammation of the brain and spinal cord (A69.22 Other neurologic disorders in Lyme disease)
  • Nerve pain (M79.2 Neuralgia and neuritis, unspecified)
  • Shooting pain (R52 Pain, unspecified)
  • Problems with short-term memory (F06.8 Other specified mental disorders due to know physiological condition)

Screening and Pathology of Lyme Disease

The CDC does not recommend laboratory tests for patients who do not have typical symptoms of Lyme disease. For those who have symptoms of Lyme disease, the CDC recommends a two-step process when testing for it.
Step 1: is an enzyme immunoassay (EIA) methodology: CPT® 86618 Antibody; Borrelia burgdorferi (Lyme disease)
This methodology uses the basic immunology concept that an antigen binds a specific antibody. Such antigen molecules, which can be identified in a fluid sample, include molecules such as peptides, hormones, and proteins. The enzymes commonly used in this process include glucose oxidase and alkaline phosphase. The antigen in the fluid binds to an antibody, which is then detected with another enzyme-coupled antibody. A color change, or fluorescence, indicates the presence of the antigen. The amount of the biological molecule determines the color observed. If the first step is negative, no further testing is recommended.
Step 2: CPT® 86617 Antibody; Borrelia burgdorferi (Lyme disease) confirmatory test (eg, Western Blot or immunoblot)
If the first step is positive or indeterminate and the patient has had signs or symptoms:

  • for less than or equal to 30 days, an immunoglobulin M (IgM) Western Blot (WB) test is performed; or
  • for more than 30 days, the immunoglobulin G (IgG) WB is performed.

Results are considered positive for Lyme disease only if the EIA and immunoblot are both positive. The WB is used to confirm a positive EIA, and the combined tests are 99.9 percent accurate.

What Is a Western Blot?

The immunoblot is a laboratory test that looks for antibodies made by the body against different antigens that are part of the B. burgdorferi bacteria. The WB was the first type of immunoblot developed for Lyme disease testing.
The immunoblot produces something that looks like a bar code with several lines or “bands.” Each band represents antibodies or proteins to a different component of the bacteria. The presence of any one or two bands is not particularly significant, but the combination of multiple, specific lines identifies the infection as being due to B. burgdorferi.
A striped type of immunoblot that does not require human interpretation of the bands has since been approved by the Food and Drug Administration.

Unproven Tests

There are laboratory tests for Lyme disease that are not recommended by the CDC because their accuracy and clinical usefulness have not been adequately established. They include:

  • Capture assays for antigens in urine
  • Culture, immunofluorescence staining, or cell sorting of wall-deficient or cystic forms of B. burgdorferi
  • Lymphocyte transformation tests
  • Quantitative CD57 lymphocyte assays
  • Reverse Western Blots
  • In-house criteria for interpretation of immunoblots
  • Measurements of antibodies in the joint fluid
  • IgM or IgG tests without a previous enzyme-linked immunosorbent assay/indirect immunofluorescence assay

Alternate Test Requires Special Circumstance

Polymerase chain reaction (PCR) assays are being used more often in the clinical setting to detect viral DNA; and because the PCR assay detects the DNA of the B. burgdorferi bacteria drawn from an infected joint, it may prove useful for detecting Lyme disease in patients with symptoms that have not improved after treatment.
Although B. burgdorferi can be detected by PCR in biopsy samples of infected skin, synovial tissue, or synovial fluid; skin biopsy is not generally recommended because patients with erythema migrans (the classic bull’s-eye rash seen in Lyme disease) can be reasonably diagnosed and treated based on history and clinical signs and symptoms. The utility of testing synovial fluid is not well established, and CDC recommends testing only under special circumstances.
In view of these limitations, there are no PCR-based assays for the diagnosis of Lyme disease currently cleared by the FDA and two-tiered serology remains the mainstay of laboratory testing for Lyme disease.

Antibiotics Are Key

A diagnosis of Lyme disease should be made after evaluation of a patient’s clinical presentation and risk for exposure to infected ticks and, if indicated, after the use of validated laboratory testing. Most cases are successfully treated with oral antibiotics such as doxycycline, amoxicillin, or cefurozime axetil.


CDC. Why Is CDC Concerned About Lyme Disease?
PA Penn Live. “Lyme Disease Now in All States, but Pa. Has Most Cases.” Aug. 9, 2018.
PA Penn Live. “Yes, There Are a Lot More Lyme Disease-Carrying Ticks in Pa. Today: Penn State study.” May 8, 2019.
CDC. Post-Treatment Lyme Disease Syndrome.

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