Lyme/Borreliosis is a zoonotic disease spread by the bite of a tick infected with spirochaetal bacteria Borrelia species (which apart from the normal nucleolar DNA have plasmids . These are separate entities of DNA in the body of the bacteria)
Ticks have a 3 stage lifecycle over a 3 year period. Eggs hatch into larvae (6 legs) blood meal,nymph (8 legs ) blood meal,adult (8 legs) blood meal egg laying. If at any stage the ticks pick up an infection that line of ticks carry the infection through all stages ( vertical transmission ) blood meals are normally taken from mammals and birds When an infected tick bites a patient, say human a sequence of events takes place.Borrelia species are attached to the tick gut and the blood releases them to move to the salivary glands ( tick moves from ground temperature to body heat ) Simultaneously the outer surface protein changes from OSP A to OSP C. This is the reason the tick must be attached for 36 hours or more Tick saliva is anaesthetic,anticoagulant and contains a protein SALP15 ( homologues in Ixodes ricinus ticks) which coats the bacteria as they pass into the host's body and is disseminated by the blood throughout the body. This protein protects the bacteria from triggering an immediate immune response.This is a SIGNIFICANT FEATURE
Borreilia bacteria causing disease
Borrelia burgdorferi ( Bb ).....mainly arthritis
Borrelia garinii ( Bg )...mainly nervous
Borrelia afzelii ( Ba )...mainly skin
newly diagnosed species
Borrelia valaisiana ( Bv )...skin ?
Borrelia spielmanii ( Bs )....skin ?
Symptoms of Lyme/Borreliosis
Stage 1 Early localised disease.
Symptoms start one to two weeks after the tick bite. Earliest sign is Erythema migrans so-called " bull's eye " rash.A central spot of red which is warm to touch. not raised and non painful, as it progresses outwards centre goes pale.
This is pathognomonic (definite Lyme /Borreliosis ) Only occurs in 30-80 % of cases.A blood sample at this stage is useless as body immune response delayed ( refer SALP15 ) FALSE NEGATIVE
Stage 2 Early disseminated Lyme/Borreliosis
Occurs weeks after the tick bite.
Flu like symptoms
Enlarged lymph glands
Rash may appear over the body other than the position of the tick bite
Neurological signs Numbness, tingling in muscles, Bell's palsy and cardiac disturbance
Stages 1 and 2 can overlap.
Stage 3 Late disseminated disease
Arthritis in one or more large joints
Disturbance of heart rhythm
Short term memory loss
Problems following conversations
Numbness in arms,legs,feet
CLINICAL EM diagnostic
Blood tests Elisa initial test confirmed by Western blot
polymerase chain reaction PCR
As the symptoms are non specific mainly full history and lifestyle assessment is paramount. If in doubt treat.
Recommended treatment high dose doxycycline. Most effective 200mg twice daily for a month.
Photosensitisation protect against strong light.No alcohol. Marmite to supplement gut products lost by gut sterilisation
Criticisms of diagnostic criteria
Blood samples submitted to laboratory are taken before antibodies develop ( delayed immune response )
Specific challenging material ( probes ) Bg has 7 different serovariants
Dedicated protocols: American protocols not appropriate for European diagnoses
Lyme/Borreliosis is the most common tick borne disease in Europe, must be taken seriously as grossly under diagnosed
Only in Scotland and Rep of Ireland a notifiable disease not rest of UK
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