|
Normal Result |
|
|
IgG |
Negative |
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IgM |
Negative |
Patient requests are tested in a batch size of 6
Euroimmun EUROLINE Line Immunoassay (LIA).
The LIA uses recombinant antigens (VlsE for IgG and OspC for IgM) and can detect both USA and European strains of Borrelia. The LIA is considered a confirmatory assay and, as such specimen referral to other testing sites will not be provided.
Reporting of results for both IgG and IgM assays is qualitative.
Lyme Disease is caused by the spirochete Borrelia burgdorferi. The disease has been documented in Europe and more recently in the United States during an epidemic in Old Lyme, Connecticut, in 1975.
The disease is transmitted by a tick which lives on animals such as deer, wild mice, birds, racoons, horses, dogs and cats. B.burgdorferi was first isolated from the Ixodes dammini tick.
The disease generally occurs in stages, however, the early stages of the illness may be asymptomatic and the patient may present with late manifestations.
False positive results occur in patients with other pathogenic spirochetal diseases such as syphilis, yaws, pinta, leptospirosis, and relapsing fever. As well as patients with mononucleosis (EBV), lupus erythematosis, and rheumatoid arthritis.
Although the clinical picture of Lyme disease is quite different from that of active syphilis, an easy means of differentiating these two diseases is by the use of the VDRL or RPR tests. In active syphilis the VDRL or RPR are positive. In Lyme disease the VDRL and RPR are generally negative.
Patients with very early stage Lyme disease may test negative, because IgM antibodies may not have reached detectable levels.
Antibiotic therapy given early in the disease may prevent the development of an antibody response.
All test results must be considered in conjunction with the clinical picture presented by the patient.
The following are symptoms of Lyme Disease:
A red lesion near the site of the tick bite is called erythema Migrans (EM).
Arthritic symptoms
Febrile illness
Headaches
Dizziness
Stiff neck
Fatigue, malaise and muscular aches
Abdominal pain
Irregular pulse and heart beat
The clinical progression of the disease can be divided into three stages:
Stage I
EM may develop within a few days to weeks following a tick bite. During this period, symptoms of headache, malaise, myalgia, fever, arthralgia, fatigue and lymphadenopathy are usually present.
Stage II
Neurological, cardiac and musculoskeletal involvement. These symptoms may appear from weeks to months following Stage I. Dizziness, weakness, irregular heartbeat, Meningitis and inflamed nerve roots in the neck are general symptoms of Stage II.
Stage III
Arthritic symptoms. Generally the large joints are affected with pain and swelling. Other symptoms include mood swings, loss of memory, inability to concentrate and poor motor co-ordination. The arthritic attacks may occur for month or years.
Direct culture from the EM site has been reported, as well as isolation from blood and spinal fluid. Direct culture methods cannot be relied upon in the diagnosis of Lyme Disease due to competing microflora, complicated growth requirement and the slow growth rate of the spirochete.
Serological methods are the most common methods of choice. Patients with Lyme Disease produce antibodies of the IgM class during the first four weeks after the onset of EM and produce IgG antibodies more slowly. Both IgM and IgG titres can remain positive for many months or years.
Cross-reactivity with other pathogenic spirochetal diseases such as Syphilis has been reported. Additional cross reactivity has been reported in Leptospirosis, Infectious Mononucleosis and SLE.
References
Lyme Disease IgM IFA Test System kit insert. MARDX Diagnostics, Inc
For further information contact the laboratory (contact via Lablink: 22000 or (09) 307-8995 or 0800 522 7587) ,or:
the Virology team
virology@adhb.govt.nz