Congenital Syphillis Flashcards
What population/demographic accounts for most cases of syphilis in Canada?
What 2 provinces have highest incidence?
Heterosexual transmission in inner city populations
(previously men who have sex with men)
Highest incidence in BC & Alberta
Most recent incidence of congenital syph in Canada?
10 cases per year
How is syphilis usually transmitted? What are rarer mechanisms of transmission?
Usually - sex with person infected with syphilis within the past year
Rarely - blood transfusion, oral secretions, needle sharing, direct contact with infected lesion
Why are all pregnant women assumed to be at risk?
Many infected pts are asymptomatic
What is the risk of vertical transmission if:
(1) Untreated primary or secondary syph during pregnancy
(2) Early latent syph
(3) Late latent syph
(1) Untreated primary/secondary - 70-100%
(2) Early latent - 40% (at risk for reactivation)
(3) Late latent - 10%
When are fetuses infected with syphilis?
In utero, after 4 months gestation
but can occur as early as 9 weeks OR with during birth with active lesion
When should syphilis serology be done on pregnant patients?
When should rescreening be done and what population?
- Syph serology at first prenatal visit
- Rescreen at 28-32 weeks + at delivery for high risk women (i.e. high incidence of syph in country of origin)
What if maternal serologies not done before delivery?
Do not discharge newborn until maternal serologies drawn and f/u arranged
What are the different types of syphilis serology tests for screening vs confirmation?
Nontreponemal tests for screening:
- RPR (rapid plasma reagin)
- VDRL (venereal disease research lab)
Treponemal test for screening:
- EIA (enzyme immunoassay)
Treponemal test for confirmation:
- florescent treponemal antibody absorption (FTA-ABS)
- T pallidum particle agglutination (TP-PA)
- Line blot immunoassay (INNO-LIA)
If RPR negative, TP-PA negative, FTA positive – what is the most likely condition?
Primary syphilis
If RPR positive, TP-PA positive, FTA-ABS positive – what is the most likely condition?
Any of:
- Any stage of syphilis
- Old treated syphilis/being treated
- Pt from endemic country
- Lyme disease/yaws/pinta
**If both confirmatory tests+ and RPR+, CAN be active syphilis (along with other possibilities). RPR- means not most active syphilis.
If RPR negative but TP-PA/FTA positive – what is the most likely condition?
Any of:
- Old treated syphilis
- Early infection (early primary)
- Late latent/tertiary syphilis
- Persons from endemic countries
- Lyme disease/yaws/pinta
If RPR positive, TP-PA/FTA negative – what is the most likely condition?
False positive
Some reasons for this:
- collagen vascular diseases
- pregnancy
- IVDU
- Lyme disease
- Test technique
If RPR negative (and conf tests not performed) – what is the most likely condition?
Not syphilis!
Repeat serology if at risk
EIA indeterminate
RPR negative
Confirmation test neg/indeterminate
What is the most likely condition?
May be in early serovonversion
Needs repeat serology
(if repeat same, not syphilis!)
EIA indeterminate
RPR negative
Confirmation test positive
What is the most likely condition?
Any of:
- Early primary
- Late latent
- Previously treated
- Endemic country
- Lyme disease
EIA positive
(RPR positive OR negative)
Confirmation test negative
False positive
EIA positive + RPR positive
Confirmation test indeterminate
Repeat serology
(if conf test + – any stage of syphilis or treated syphilis or endemic person)
(if unchanged - false positive)
EIA positive
RPR negative
Confirmation test indeterminate
Repeat serology
(if conf test + – any stage of syphilis or treated syphilis or endemic person)
(if unchanged - false positive)
EIA positive
RPR negative
Conf test positive
Early primary, late latent, or previously treated; endemic person, Lyme disease
- just not the most active syph*
EIA positive
RPR positive
Conf test positive
Any stage of syphilis
(more likely to be infectious if RPR titre 32 dilutions+)
- Includes old treated syphilis, being treated
- Endemic persons
- Lyme/yaws/pinta/bejel
What is the usual screening approach for syphilis in Canada?
RPR initial screen
Treponemal test to confirm
- Others use EIA as initial screen (more sens and spec than RPR)
- Still need to obtain RPR titres if EIA positive – RPR used for staging of infection
How long with treponemal tests remain reactive for after treatment?
Usually for life, unless tx started v early in course of infection
How do you monitor for adequacy of maternal syphilis tx?
Decline in RPR titres!
