Rickettsia/Borrelia

Question 1

What is the vector and rickettsial bacteria associated with epidemic typhus

Answer 1

Bacteria - R.prowazekii
Vector - Louse-borne

Question 2

What is the vector and rickettsial bacteria associated with murine typhus

Answer 2

Bacteria - R. typhi
Vector - flea

Question 3

What is the vector and rickettsial bacteria associated with scrub typhus

Answer 3

Bacteria - R. tsutsugamushi (previously known as orientia tsutsugamushi)
Vector - Chigger mites

Question 4

True or false, the borrelia species are spirochaetes

Answer 4

True

Question 5

What is the pathophysiology behind the relapsing fever pattern in borrelial diseases

Answer 5

It is caused by the pathogen switching out the lipoportein (vlp and vsps) antigens. Tehrefore there is usually a different lipoprotein associated with every recrudescence

Question 6

There is only one country where louse-borne epidemic relapsing fever has an endemic focus. Which country is this?

Answer 6

Ethiopia

Question 7

What is the vector and organism involved in louse-born epidemic relapsing fever

Answer 7

Vector - louse (pediculus humanus)
Organism - borrelai recurrentis

Question 8

How do you diagnose borrelial diseases

Answer 8

• Microscopy of thick and thin films: would see motile long spirochaetes

Question 9

What is the reaction associated with treatment for spirochaetes such as borrelia

Answer 9

Jarisch-Herxheimer Reaction - an exacerbation of the fever and rash due to innate immune response associated with clearance of the organisms usually by penicillin (due to its bactericidal effects). Often accompanied by hypotension and other organ dysfunction may occur.

Question 10

What is the management of Jarisch-Herxheimer Reaction

Answer 10

• IV fluid challenge
• Meptazinol may diminish severity

Question 11

Are neurological cx more common in tick-borne or louse-borne relapsing fever

Answer 11

tick-borne

Question 12

Lyme disease is caused by what pathogens and vector?

Answer 12

Pathogen - Borrelia burgdorferii, B.afzelii and B garinii
Vector - Ticks

Question 13

Describe the main clinical manifestations of Lyme disease

Answer 13

1. Early localised Lyme DIsease
   - Erythema chronicum migrans
   - Evolves over 1-12 weeks, may be multiple, local proliferation of spirochaetes
   - Resolves without treatment
2. Early disseminated Lyme Disease
   - Herat and meningitisey stuff
   - Lymphocytic meningitis, Banwarth syndrome (meningitis and painful radiculopathy), facian nerve palsy, myopericarditis, variable AV block
3. Late disseminated Lyme DIsease
   - Chronic disease
   - Mostly neuro and rheum issues
   - Arthritis of one or more large joints with synovitis
   - Acrodermatitis chonica atrophicans
   Encephalomyelopathy syndromes (cog impairment, cranial/peripheral neuropathy)
   - Post-treatment Lyme Disease - ongoing fatigue

Question 14

What is the vector and organism/s involved in tick-borne endemic relapsing fevers

Answer 14

Vector - soft ticks
Organism - B.duttoni, B.hermsii, B.parkeri

Question 15

What is the management of borrelial diseases

Answer 15

Either of:
- Doxy single dose 100-200mg PO OR Penicillin 600,000IU IM single dose (high assoc with JH reaction)
- Other alternative - Tetracycline 250mg IV single dose (less assoc with JH reaction)

Question 16

Describe the treatment for rickettsial diseases

Answer 16

Doxycycline 200mg stat dose in epidemic situations otherwise at least 5/7 of for severe cases and in RMSF and 14/7 for acute QF

18-24mo + hydroxychloroquine for QF endocarditis

Question 17

What is the management of Lyme disease

Answer 17

1st line- doxxy 200mg daily for TWENTY ONE DAYS
2nd line - amoxi 2g TDS for TWENTY ONE DAYS

• Extend to 28 days for Lymearthritis or acrodermatitis
• CNS disease: ceftriaxone 2g BD daily for 21 days (doxy for 21 days = alternative)