Lyme disease Flashcards
Tick bites may not always be noticed. Most ticks do not transmit lyme disease, and prompt removal of tick reduces transmission.
Do not rule out possibility of lyme disease in patients with no clear history of tick exposure
How to diagnose lyme disease clinically?
Erythema migrans is diagnostic - usually not hot/ itchy or painful. At site of tick bite. Lasts for several weeks, usually starting 1 week after bite
correlate with exposure history
What are common symptoms of lyme disease?
Stage 1 - early localised disease 1-4 weeks
erythema migrans
flu-like illness
fatigue
Stage 2 - early disseminated disease 1-4 months fever and sweats swollen glands malaise fatigue neck pain or stiffness migratory joint or muscle aches and pain cognitive impairment headache paraesthesia.
Stage 3 - late disseminated disease
what are rarer symptoms of lyme disease?
stage 3 - late disseminated disease
neurological symptoms, such as facial palsy or other unexplained cranial nerve palsies, meningitis, mononeuritis multiplex or other unexplained radiculopathy; or rarely encephalitis, neuropsychiatric presentations or unexplained white matter changes on brain imaging
inflammatory arthritis affecting 1 or more joints that may be fluctuating and migratory
cardiac problems, such as heart block or pericarditis
eye symptoms, such as uveitis or keratitis
skin rashes such as acrodermatitis chronica atrophicans or lymphocytoma.
What are laboratory diagnostic tests for lyme disease?
Serology tests are only useful 4 weeks from symptom onset/ tick bite.
Serology tests - so ensure patient not immunocompromised
- erythema migrans present - treat patient
- first line - ELISA - IgM/ IgG
- if ELISA positive/ equivocal - immunoblot
- immunoblot positive - treat patient
- immunoblot negative - consider alternative diagnosis
- if ELISA negative - consider repeat ELISA in 4-6 weeks if symptoms persist. Perform immunoblot if symptoms remain after 12 weeks
- if immunoblot negative, and symptoms persist, consider referral to specialist. May need LP or synovial fluid aspirate
Patient says diagnosed with Lyme disease in Germany, and asking for treatment. Complaining of tiredness, headache, muscle pain
What is your approach?
Explain that Lyme disease test results are only acknowledged by UKAS accredited labs, with validated platforms, which participate in external quality assurance
Do not routinely diagnose Lyme disease based only on tests done outside the NHS, unless the laboratory used is accredited, participates in formal external quality assurance programmes and uses validated tests
Advise people that tests from non-UKAS laboratories may not have been fully evaluated to diagnose Lyme disease.
Offer to use NHS labs to test
Explain false positive and false negatives can occur in any tests
the symptoms and signs associated with Lyme disease overlap with those of other conditions
they will be assessed for alternative diagnoses if their tests are negative and their symptoms have not resolved
symptoms such as tiredness, headache and muscle pain are common, and a specific medical cause is often not found.
Which patients with suspected lyme disease require emergency referral to hospital
Follow usual clinical practice for emergency referrals, for example, in people with symptoms that suggest -
central nervous system infection
uveitis
cardiac complications such as complete heart block
When prescribing antibiotics for lyme disease, what do we need to evaluate before starting treatment?
Assess pregnancy - as cannot have doxycycline
Be aware of Jarisch-Herxheimer reaction
What are treatment options for Lyme disease?
no focal symptoms
Doxycycline 200mg OD 21 days
Amoxicillin 1g TDS 21 days
Azithromycin 500mg 17 days
What are treatment options for Lyme disease?
focal symptoms
Ceftriaxone 2g BD
Switch once improving -
Doxycycline 200mg OD 21 days
Amoxicillin 1g TDS 21 days
Why is azithromycin not used for patients with focal symptoms of lyme disease?
Can worsen cardiac abnormalities associated with lyme carditis.
But is safe to use for CNS infection
Patient is treated for lyme disease, and completes course of antibiotics.
Symptoms still persist.
what are possible explanations?
Didn’t take full treatment course
Incorrect diagnosis
Re-infection
Consider a second course of antibiotics. E.g amoxicillin if they previously had doxycycline
If had second course of antibiotics, refer to specialist for assessment
Patient is treated for lyme disease, and completes course of antibiotics.
Symptoms still persist.
What advice would you give to patient?
continuing symptoms may not mean they still have an active infection
symptoms of Lyme disease may take months or years to resolve even after treatment
some symptoms may be a consequence of permanent damage from infection
there is no test to assess for active infection and an alternative diagnosis may explain their symptoms.
they may need additional treatment for symptom relief.
What is the process of an immunoblot?
Three types of immunoblot exist -
Western blot - antibody proteins
Northern blot - identifies RNA fragments
Southern blot - identifies DAN fragments
Also called a Western Blot
can target IgM or IgG
Borrelia sample first undergoes electric current to break it down into smaller proteins. The electrphoresis causes proteins to separate according to particle weight.
Then add patient serum to exposed wells.
If patient serum has antibodies directed at specific borrelia outer surface protein A (OspA) there will be a band which forms
There is then criteria about how many bands must be present in IgM/ IgG to consider a positive diagnosis. Certain bands are more specific to borrelia species
What species of Borrelia cause Lyme disease throughout the world?
B burgdorferi - USA
B garinii - Europe
B afzelli - Europe
What are issues with immunoblot?
Not all patients have same immune response
different labs use different borrelia species for testing
patients may already have antibodies present from other infections e.g oral spirochete infections can be asymptomatic, but produce cross-reacting antibodies
