Lyme disease profoma Flashcards
Epidemiology of lyme disease?
In untreated Lyme disease, arthritis can develop months after initial infection.
Lyme disease can occur at any age, but 2 peak age groups have been identified: 10 to 19 years & 50 to 59 years.
Lyme arthritis most common in 7-10 year olds.
Onset is usually between May & October, mostly related to increased outdoor activity compared w/ the rest of the year.
NOTE- in exam, if someone goes into a forest and gets a rash, its always lyme disease
Aetiology (cause) for Lyme disease?
Lyme disease in Europe is caused by:
- Borrelia burgdorferi
- Borrelia afzelii
- Borrelia garinii
Reservoir for bacteria are Ticks that live on deer.
Infection transmitted to humans through tick bite.
Pathophysiology- how does organism cause disease?
B. burgdorferi enters joint tissue & causes inflammation.
Most bacteria recycle their peptidoglycan (PG) when they grow & divide, but B. burgdorferi cannot so it shed fragments into its surroundings.
The peptidoglycan collects in the joints.
Extreme immune response will cause damage to surrounding tissue.
In the chronic phase, antibodies against a variety of Borrelia antigens become detectable.
Major pro-inflammatory markers e.g. TNFα, are significantly up regulated in the synovial fluid.
Patients w/ Lyme arthritis (LA) mount a specific IgG response against PG^Bb which is significantly high in the synovial fluid.
Presentation of Lyme disease: early & late stage
Early localised Lyme disease
- Fever, headache & swelling of lymph nodes - may occur in absence of rash.
- Muscle ache & tiredness
- Erythema migrans rash - diagnose Lyme disease for anyone with this rash. No tests needed. (NICE)- NOTE: VIEW IMAGE
- Red “bulls eye” macule or papule appears 2-30 days after bite.
- The enlargers peripherally & clears centrally.
Early disseminated
- Dissemination occurs via the blood stream & - Malaise
- Arthralgia - joint
- Metastatic areas of erythema migrans
Neurological symptoms:
- Lymphocytic meningitis - a type of aseptic meningitis
- Cranial nerve palsies - lack of function of a nerve
- Peripheral neuropathy - results from the damage of - Radiculopathy - pinching of nerve root in spinal column.
Late disease
- Arthritis - particularly affects large joints
- Polyneuritis - where peripheral nerves are damaged.
- Encephalopathy - damage or disease that affects brain
NOTE: View images on notes!
Presentation of lyme arthritis
- Mono or oligoarthritis (2-4 joints)
- Knee most commonly affected
- Other large joints: shoulder, ankle, elbow, jaw, wrist & hip can be affected.
- Develops 1 - few months after infection
- Asymmetrical
- Very swollen but not necessarily as painful as it looks.
History for Lyme disease?
Ask about where they live - endemic areas = risk factor e.g. New Forest
- Grassland or Wooded areas in England & Highlands of Scotland are endemic areas.
Ask about where they’ve travelled e.g. US, Asia…
Ask about hobbies - do they like the countryside?
- Ask about pets & animal exposure
- Ask about their occupation
Investigations for Lyme disease? Blood test & Joint aspiration?
Blood tests:
Looking for Borrelia proteins!
1st investigation - test for antibodies using an ELISA test. If positive, 2nd investigation ordered.
- ELISA test= uses components of immune system (e.g. IgG or IgM antibodies) for thedetection of immune responses in the body
2nd investigation - Western blot test (or immunoblot) - must be done in first few weeks after infection.
- looks for presence of bothIgG & IgM antigen bandsto confirm both recent & previous exposure. Multiple bands are required for positive result
Tests may need to be repeated if negative & symptoms persist.
NOTE: blood tests have their limitations & can give false-positives & false negatives.
Joint aspiration & synovial fluid analysis:
- Joint aspiration can rule out presence of other arthritis such as gout or septic arthritis.
- BUT NOTE: B. burgorferi cannot be cultured from synovial fluid. It is the major cause of negative culture septic arthritis.
Management for Lyme disease
Antibiotics e.g. doxycycline or amoxicillin
For symptomatic relief - aspiration of joint & NSAIDs.
Patients on antibiotics should be monitored for Jarisch-Herxheimer reaction causing fevers, sweating, muscle pains from spirochetes bacteria breaking open & releasing their antigens.
Patients who continue to experience synovitis despite 2 courses of antibiotics: should receive NSAIDs, intra-articular corticosteroid injections, or DMARDs including hydroxychloroquine.
Prognosis for Lyme disease
Most features of Lyme disease respond to antibiotics, but treatment of early disease is most successful.
In late-stage disease, antibiotics eradicate the bacteria, relieving the arthritis in most people.
A few genetically predisposed people have persistent arthritis even after the infection has been eliminated because of continued inflammation.
