Lyme Disease Diagnosis
Sample
- Whole blood or citrated blood is needed.
- Other samples are CSF and synovial fluids in the acute stage.
Precaution
- Spirochetal diseases like syphilis or leptospirosis can give a false-positive reaction.
Causative Agent
- Lyme disease was first diagnosed in Lyme, Connecticut, in 1975.
- Lyme disease is caused by the spirochete Borrelia burgdorferi.
- This is caused by the bite of a deer tick. (Ixodes dammini or pacificus).
- These ticks are the best vector for Lyme disease.
- This is difficult to grow in the culture.
- It takes a long time to grow.
- Cultural success is in 50% of the cases.
- The culture of blood and CSF has a poor result.
- Serological tests are more helpful.
- Its diagnosis was established in early 1980.
- This is caused by the bite of a deer tick. (Ixodes dammini or pacificus).
Reservoir
- Rodents and deer serve as the natural reservoir for these ticks. Other animals are sheep and cattle.
Morphology
- These are 0.18 to 0.25 X 4.3 μm. These are flexible helical spirochaete.
- These are a gram-negative organism.
- Culture: These are microaerophilic, growing at 34 °C in a special medium.
Lyme disease has the following presentation:
- This is a chronic inflammatory disease which first shows a distinct skin lesion, Erythema migrans (erythema chronicum migrans).
- It starts at the site of the bite as a red macule.
- There is a central clearing at the site of the bite.
- Erythema migrans.
- Late Lyme disease.
- Lyme arthritis.
- Cardiovascular involvement.
- Neurological involvement and presentation.
Signs and symptoms:
- This disease was first time diagnosed in Lyme, Connecticut 1975.
- This disease usually starts in summer with skin lesions called Erythema chronicum migrans.
- This lesion usually appears at the site of the deer tick bite.
- Characteristically there is:
- Fever.
- A headache and a stiff neck.
- There is fatigue.
- There are muscle and joint pain.
- These patients may develop arthritis and meningitis.
- There are chronic meningoencephalitis and peripheral neuritis.
- In CVS there are myocarditis, pericarditis, and conduction defects.
- There is arthritis of large joints and often recurrent.
Diagnosis
- The culture medium used in Kelly’s medium, and BSK II.
- Antigen detection. Urine shows excreted B. burgdorferi.
- Polymerase chain reaction (PCR).
- Antibody detection. This is the most common method.
- It is negative when there is a low level of IgM and IgG antibody.
- IgM titer peak is from 3 to 5th week of disease onset.
- Then it declines.
- A single high titer of specific IgM is diagnostic.
- IgG is low during the first few weeks of disease and reaches the maximum level by 4 to 6 months later on.
- Indirect immunoassay.
- Enzyme immune assay has replaced the indirect immunoassay.
- Western Blot method is the confirmatory test.
- Skin biopsy of the affected area surrounding the erythema migrans.
- Silver stain reveals spirochetes.
- CDC criteria:
- Isolation of B.burgdorferi.
- The Positive IgM and IgG antibody in Blood or CSF.
- The positive antibody titer in the sera of convalescent or acute stage.
Treatment
- Mostly this disease is treated with amoxicillin and doxycycline for 3 weeks.
- Some time may need IV therapy.
- These are also sensitive to penicillin and tetracycline.