Syphilis Flashcards
Define syphilis.
STI caused by spirochaetal bacterium Treponema pallidum found only in humans. Most infection probably occurs from direct contact with syphilitic lesions.
How common is syphilis?
~6million infections worldwide per year
Incidence of congenital, primary and secondary syphilis increasing
Most common at 25-29yrs
In 2019 56% of all cases occurred in MSM
What is the pathophysiology of syphilis infection?
- Probably enters at areas of minor abrasion
- Can occur by oro-genital transmission too
- Has primary, secondary, latent and tertiary stages
- Up to 40% will progress from secondary to tertiary (neurosyphilis, gummatous and CVD) syphilis
- Neurosyphilis can occur at any stage
Describe primary syphilis.
- Initial inoculation
- Solitary painless chancre - within 10-90 days of exposure and disappears by 2-8 weeks
- Localised lymphadenopathy
- May have fever, myalgias, arthralgia, fatigue etc
Describe secondary syphilis.
Spirochaetaemia and widespread dissemination to skin and other tissue
Symptoms 4-8 weeks after primary infection but can occur at up to 6 months
- skin - rash with pink to brown macules involving palms/soles in 50%
- oral - “mucous patches” resembling snail tracks
- early neurosyphilis e.g. CN deficits or aseptic meningitis
- ocular - anterior or posterior uveitis
- genito-ingunal - tinea mimicking rash or condyloma lata
- organ specific - acute hepatitis, nephrotic syndrome
Describe latent syphilis.
Asymptomatic infection but positive serology. Follows primary and secondary syphilis. Usually > 1yr after infection was acquired
Early latent = positive serology and history < 1 yr ago - may get single penicillin
Late latent = positive serology and history > 1yr ago - several penicillin doses
Describe tertiary syphilis.
Neurosyphilis -
- tabes dorsalis - damages dorsal columns and sensory roots so similar symptoms to B12 deficiency e.g. areflexia and Romberg’s sign
- gait impairments
- dementia, confusion, seizures
- Argyll-Robertson pupil
Gumma - ulcerating granulomas on skin, bone and internal organs
Cardiovascular - usually affects aortic root
- aortic aneurysms
- coronary arteritis
What % of patients with untreated syphilis progress to tertiary syphilis?
14-40%
What test are available for diagnosing syphillis?
Serology - use both:
Treponemal tests - T enzyme immunoassay (EIA), TP particle agglutination assay (TPPA), TP haemagglutination assay (TPHA), immunocapture assay (ICA)
Non-treponemal tests - confirms diagnosis; work by detecting antibody response and can be used to monitor treatment response by titres; e.g. RPR and VDRL test
Microscopy - until recently it was not possible to culture T.pallidum but now a complex technique is available in specialist settings
How long is the incubation time for serological syphilis tests?
3-4 weeks in general
Secondary syphilis will be strongly positive
Which serological tests is used for screening for syphilis?
EIA
What other investigations may be done in syphilis after diagnosis?
CSF examination - if neurosyphilis signs; confirmed by WCC >10cells/mm3, protein >50mg/dL, positive CSF VDRL.
CT/MRI brain
CXR - may show aortic aneurysm or aortic calcification
HIV test
What are Argyll-Robertson pupils?
Bilaterally small, irregular pupils, which do not constrict when exposed to bright light BUT constrict in response to accommodation
This is a feature of tabes dorsalis occurring in tertriary syphilis
What are the risk factors for syphilis?
- Sexual contact with infected person
- MSM
- Illicit drug use
- Commercial sex workers
- Multiple sexual partners
- People with HIV or other STI
- Syphilis during pregnancy (risk for congenital)
What is the management of syphilis?
Early infection/contacts:
- Benzathine penicillin 1.8g IM once only
- 2nd line: doxycycline 100mg PO BD 14days
- Monitor RPR or VDRL titres to assess response - 4-fold decreases shoud occur
With neurosyphilis:
- Benzylpenicillin IV for 14days then IM benzathine penicillin once weekly for 3 weeks
- +/- prednisolone - prevents JH reaction
