Guide to Understanding Lyme Disease

In the United States, Lyme disease is the top infectious disease in terms of spread rate. Out of every 100,000 individuals, 7.9 have Lyme disease. 49 states also report having cases of the disease. Other countries like Canada, the United Kingdom and other European nations also have Lyme disease as the most common tick-borne illness. The type of tick also varies depending on the geographical region. Other animal species like flies, mosquitoes, fleas and lizards are also suggested to successfully transmit Lyme disease to human beings.

The Tick Types

Borrelia burgdorferi is the most prevalent type of tick found in deer and the white-tailed mouse. Borrelia afzelii is found in rodents like rats and is more common in Europe. Borrelia garinii and Borrelia valaisiana are found in birds. Borrelia burgdorferi sensu stricto are found both in rodents and birds and are common in Colombia and Bolivia. Borrelia burgdorferi sensu lato are found in lizards and are common in Germany, Poland, England and Japan. The genus Ixodes is also highly associated with Lyme disease. Ixodes dammini is the most common in the United States found in grassy and woody places.

The most common tick types go through three life stages namely: larva, nymph and adult. It takes around two years and three different hosts during the entire process. The tick feeds once during each life stage on rats, dogs, deer, cows and even human beings. The nymph stage is regarded as the part wherein Lyme disease is transmitted. Ticks are usually found on the head, neck, toes and armpits where there is enough moisture and warmth.

The Early Symptoms

About 80% of Lyme disease incidences are characterized by a rash or lesion that looks like a bull's-eye. The pattern is called erythema migrans which develops anywhere from a few days to a few weeks after being bitten by an infected tick. Tick bite is almost unnoticeable since it is painless. The rash can appear like a growing red ring, a bull's-eye with a light ring surrounded by a dark one or fully red and round. The insect bite is the cardinal sign of Lyme disease but is sometimes hard to diagnose since the bacteria needs to be magnified 400 times to be detected.

Together with the rash, other symptoms indicative of flu like sore throat, muscle pain, fatigue and headache may also appear. It is possible to get flu-like symptoms without the presence of a rash and vice-versa. Incubation period lasts around 1 or 2 weeks while it is also possible for it to delay up to several years before symptoms appear. Uncommon symptoms include palpitations, heart block and altered mental state (neuroborreliosis)

Untreated early symptoms can last for a few months up to several years then may disappear. Complications and late symptoms will then follow which are more severe and long lasting. Common chronic symptoms are muscle and joint pain and neurological symptoms like burning and tingling sensation in the extremities, meningitis, depression and fatigue.

Meningoencephalitis, myocarditis and frank arthritis are common manifestations in chronic Lyme disease. Other organs like the lungs, heart and stomach may also be affected. Chronic Lyme disease can be misdiagnosed at times because the symptoms are similar to several other known illnesses.

Other neurological and neuropsychiatric symptoms due to swelling and increased pressure in the brain can also manifest like muscle twitching, paresthesia, memory less, difficulty sleeping and changes in affect or mood. Other neurological problems can develop like encephalitis, encephalomyelitis and Bell's palsy.

The affected person may also present problems in sexuality like breast or testicular pain, sexual dysfunction and loss of libido. Other related symptoms may also arise like sudden weight gain or loss, swollen lymph nodes, high fever or chills, hypersensitivity to alcohol, eye and kidney infection and photo sensitivity.

Lyme disease tests look for the presence of the bacteria transmitted by ticks. The microscopic bacteria need to be found to confirm that a patient has Lyme disease since several symptoms are also very similar to other types of illnesses. Before any diagnostic procedure is done, doctors will take the patient's medical history and physical exam to check if there are any possible instances wherein the patient might have been infected by ticks.

Antibody Tests

Antibody tests aim to find the antibody that specifically fights the bacteria Borrelia burgdorferi or whichever pathogen that may have been transmitted. Antibodies are formed after the human body detects bacterial presence and can stay for as long as a few months up to several years.

Antibodies can be clearly seen 2 months after the patient has been infected but finding them cannot specifically determine the exact period of Lyme disease transmission. The antibody tests particularly look for high titers of immunoglobulin G or M that acts on bacterial infection. The three antibody tests are namely the ELISA test, IFA test and the Western Blot test.

ELISA stands for enzyme-linked immunosorbent assay. This is a very quick and common serological laboratory test for Lyme disease since it is highly sensitive in detecting Lyme antibodies. It is also the most frequently done test to check for chronic Lyme disease.

There are two approved ELISA tests:
a. Whole cell sonicate ELISA
b. C6 Lyme Peptide - more accurate

IFA stands for indirect fluorescent antibody. This is also done to check for Lyme antibodies.

This is another serological laboratory test that checks for Lyme antibodies. It is done after the ELISA or IFA test to confirm the initial results. Western blot is the most specific among the three. The infection is confirmed with positive results.

Other Tests

PCR or polymerase chain reaction test is done to detect the DNA or genetic makeup of the spirochete bacteria that cause Lyme disease. At present, a PCR test is the only practical means of detecting Borrelia. Other diagnostic tests that are still being developed are Lymphocyte Transformation Test and Focus Floating Microscopy. New tests are detecting other factors related to Lyme disease such as chemokine CXCL13 that may indicate neuroborreliosis. A skin culture is done by taking a tissue sample to look for the Lyme bacteria.

For late stages of Lyme disease, PCR and antibodies present in the cerebrospinal fluid or CSF are no longer reliable due to the diffuse encephalopathy. Instead of intrathecal and serological testing, imaging like PET and SPECT scan is done to check the spread of infection in the brain.

SPECT or single photon emission computed tomography imaging actually evaluates brain function but shows global hypoperfusion through the white matter in the brain typical of Lyme disease, HIV and viral encephalopathy patients. A MRI scan can help in defining a diagnosis by showing white matter lesions that may indicate neurologic Lyme disease. The scans cannot fully diagnose Lyme disease but with further serological tests, a final diagnosis can be made.

How the Tests are Done

The ELISA, Western Blot and PCR tests can be done by acquiring CSF via lumbar puncture or venipuncture. Lumbar puncture is more useful in making a diagnosis; however, it is very difficult to detect antigen in the CSF. ELISA and Western blot are the basic tests required by the Center for Disease Control or CDC.

The ELISA test is done first and if it renders positive or unclear results, Western blot follows for confirmation. During Western blot, the immune system response of the patient is presented through blots that indicate Borrelia burgdorferi antibodies. Although the test cannot fully confirm a diagnosis, reports show that the test is reliable more than 90% of the time.