Lyme disease
Borrelia burgdoferi
How does the bacteria get into the skin
Via tick saliva
Acute infection is established by binding to epithelial and dermal glycoproteins
Erythema migrans occurs in early localised disease. How long after the tick bite does it appear
1-2 weeks
occurs in 80% cases
lesions expand over several days- weeks
I have run out of questions!
Have 100 points on me!
How is localised disease treated
If no features of disseminated disease =
PO doxy 100mg BD 21/7 or
PO Amox 500-1g TDS 21/7
If suspect Lyme but no EM - can intiiate abx until await serology
10-19 years
50-59 years
How long does it take to establish an acute infection
48 hours - Tick needs to be 'feeding' for this long
What are the most common locations for erythema migrans? (4)
Axillae
popliteal fossae
neck
Belt line
Name 3 things that can be done to rule out other clinical manifestations of Lyme disese
ECG
CT/MRI (neurological factors)
X-ray - exclude fracture, gout, haemarthrosis
What is the treatment for patients with cardiac involvement
Admit to hosp
IV ceftrioxone 2g OD 14-21/7
alternative - BenzP or cefotaxime
Cardiac monitoring required
What type of bacteria is Borellia burgdorferi (need more than the gram status)
Gram negative
Obligate
Flagellated spirochetes
(Looks like noodles)
How many hours does it take for the bacteria to disseminate at distanct sites - which results in systemic manifestations
48-72 hours
What systems are involves in early disseminated disease (5)
Cardiac
neurological
Ocular
MSK
Cutaneous
What is measures in serology for diagosis of Lyme disease
How are patients with neurological involvment treated
CNS/brain parenchyma = IV antibiotic
Confined to PNS can give IV ceftrioxone or cefotaxime or benzP - doxycycline (PO) also affective in early disease
treat for 2-4 weeks
The ticks become infected with the bacteria by feeding on infected animals - which are the main animals
Mice
Squirrels
Birds
Deer (not usual vectors, but becoming more so due to climate change)
What are the main sites the bacteria spreads to within several weeks of inoculation (5)
Blood
CNS
Myocardium
Muscles
Bones
What is Borrelial lymphocytoma
rare cutaneous manifestion, mainly in children
Painless blue-red swelling
usually earlobe, nipple or scrotal area
What is the process of diangosis if erythema migrans not present
2 step process
Intiial EIA (enzyme immunoassay
Positive = western blot for confirmation
Negative - no further testing
Can repeat after 2 weeks and early disease testing may precede antibody response
What is the treatment if there is MSK involvment and oral antibiotics and simple analgesics arent working
IV ceftrioxone
Still failure to response - seek rheumatology opinion
The name of the main tick that carries the bacteria for Lyme disease (fancy/scientific name and common name)
Ixodes ticks
aka Deer ticks
How does Borellia evade host immune response?
IgM antbiodies generated against surface proteins of the bacteria within days
Bacteria downregulates the expression of key surface proteins (prevent antobody mediated killing)
Some strains have mechanism which inactivate neutrophil and macrophage recruitment and can express proteins to inactivate complement system
What is Acrodermatitis chronica atrophicans (ACA)
Cutaneous manifestation of late lyme disease
Blue-red indurated lesions on sun exposed skin of extremities
What is the post exposure prophylaxis for Lyme disease
oral doxycycline in high risk cases within 72 hours of bite
High risk = tick attachment for >36 hours & travelling in endemic area
What is jarisch Herxheimer reaction
Acute transient reaction occuring within 24 hours of inititating abx therapy for spirochetal infection
Due to acute inflammatory response to release of spirochetal lipoproteins in blood after bacteria death
Fever, rigors, tachycardia, hypotension, N&V, headache, flushing. if severe hypotension may need resus