Key words
• Borrelia– Vincent’s angina– Recurrent fever– Lyme Disease
• Ixodide tick
• Leptospira– L. icterohaemorrhagiae
• erythema chronicum migrans• Weil’ disease (leptospirosis)
– Transmission - urine of rats
B.vincenti
• Normal mouth commensal• May give rise to ulcerative
gingivostomatitis or oropharyngitis (Vincent’s angina) during malnutrition or viral infections
• B. vincenti always associated with fusiform bacilli – fusospirochetosis
• Diagnosis – gram staining of exudates
• Treatment – Penicillin
B. burgdorferi
• Causes Lyme disease, transmitted by the bite of Ixodid ticks (deer tick)
• Characteristic rash – erythema chronicum migrans
• Diagnosis – culture, serological tests• Treatment – Pen, tetracyclines,
cephalosporins in early stages.– Late stage – Antibiotics ineffective.
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Lyme disease - symptomsLyme disease - symptoms• bacteremia
– acute
• arthritis• cardiac• neurologic
– chronic * weeks, months later
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DiagnosisDiagnosis• serum antibodies to serum antibodies to B. burgdorferiB. burgdorferi.
• laboratory strainslaboratory strains– grow extremely slowly grow extremely slowly – tissue culture media tissue culture media – not bacteriological medianot bacteriological media
• patient body fluids/tissue samplepatient body fluids/tissue sample– almost never growthalmost never growth
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• acuteacute– responds to antibioticresponds to antibiotic–antibodies not detectableantibodies not detectable
• late diagnosislate diagnosis– not curablenot curable– antibodies detectableantibodies detectable
A physicians dilemmaA physicians dilemma
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Lyme DiseaseLyme Disease - -etiologyetiology
• reactive arthritis similar to reactive arthritis similar to – Reiter's syndromeReiter's syndrome– rheumatic feverrheumatic fever
• resembles rheumatoid arthritis.resembles rheumatoid arthritis.
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Relapsing feverRelapsing fever
• transmissiontransmission–tick-tick-B. hermsiiB. hermsii* rodent, primary hostrodent, primary host
– lice-lice-B. recurrentisB. recurrentis * human, primary hosthuman, primary host
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““Relapsing” fever Relapsing” fever • immune response develops immune response develops
– disease relapsesdisease relapses
• new antigens expressed new antigens expressed – no immunity no immunity – disease reappearsdisease reappears
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DiagnosisDiagnosis
• no culture no culture
• no serological testno serological test
• detected - blood smeardetected - blood smear
Leptospira
• Very thin, delicate spirochetes with hooked ends
• 2 species are recognised:1. L. interrogans – include human pathogenic
serogroups: L.icterohaemorrhagiae (rats are the reservoir)
2. L. biflexa – saprophytic, mainly found in surface water.
Laboratory characteristics
• Morphology – stained with Giemsa/ silver impregnation, hooked ends resemble umbrella handles
• Culture – media (semi solid/ liquid) enriched with rabbit serum - Fletcher’s medium
• Pathogenicity – causes Weil’ disease (leptospirosis)
Weil’s disease
• Transmission - Leptospires in water contaminated by the urine of rats; enters the body through cuts or abrasions on the skin or through intact mucosa of mouth, nose or conjunctiva
• Incubation period – about 10 days (2 to 26)• Mild fever to severe or fatal illness with
hepatorenal damage• Fever, rigors, headache, vomiting, icterus,
purpuric hemorrhages