Answer 92 - Serological tests for syphilis
A positive VDRL (venereal disease research laboratory) test with negative TPHA and FTA (Treponema pallidum haemagluttinin and fluorescent treponemal antibody) tests is consistent with:
False a. early infectious primary syphilis
False b. treated syphilis
True c. glandular fever
False d. late syphilis
False e. previous yaws infection
F F T F F
VDRL:
usually becomes positive 3-4 weeks after primary infection,
becomes negative about 6 months after treatment,
is a marker of disease activity,
if accompanied by a negative TPHA and FTA usually indicates a biological false positive.
Table 92
| Causes of biological false positive VDRL |
Mycoplasma infection
measles
chicken pox
glandular fever
hepatitis
rheumatoid arthritis
systemic lupus erythematosus
polyarteritis nodosa
malignancy
cirrhosis |
FTA:
positive in 90% of cases of primary syphilis,
positive in all late cases,
does not distinguish syphilis from yaws.
A negative VDRL with a positive TPHA and FTA may be due to early primary syphilis, yaws, congenital syphilis, latent, late or treated syphilis.
