Syphilis – CSF
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Testing for syphilis serology on CSF samples is indicated for routine diagnosis of suspected neurosyphilis cases and monitoring of treatment of diagnosed neurosyphilis. It is also recommended to be performed on all patients with human immunodeficiency virus (HIV) infection and syphilis of any stage, all infants with suspected congenital syphilis.
Submission and Collection Notes
Submit a blood sample along with the CSF for Clinical Syphilis Serology. Refer to the Syphilis serology test information sheet for collection information.
Indicate on the General Test Requisition Form whether the test is for diagnosis or monitoring treatment, and provide the date of onset, reason for testing including if the specimen is for follow-up or prenatal, symptoms, and if there is a chancre present.
Storage and Transport
Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.
Place specimen in biohazard bag and seal. Specimens should be stored at 2-8°C following collection and shipped to PHOL on ice packs.
Test Frequency and Turnaround Time (TAT)
Syphilis serology on CSF samples is performed 2-3 times per week or as needed.
Turnaround time is up to 5 days from receipt by PHO laboratory.
CSF specimens for syphilis serology are screened using the VDRL (Venereal Disease Reference Laboratory) test. This test detects non-treponemal antibodies present in patients with syphilis.
VDRL reactive samples are further tested by TPPA, a qualitative gelatin particle assay that is used for the detection and confirmation of treponemal antibodies.
Due to the low sensitivity of the VDRL test, a negative result does not rule out neurosyphilis. The VDRL non-reactive samples are further tested by FTA-ABS, a sensitive but not specific indirect immunofluorescent antibody test detecting the treponemal antibodies.
The CSF-VDRL test may be falsely positive when the CSF is visibly blood-tinged and the serum nontreponemal test titer is high. Other conditions such as malaria, systemic lupus erythematosus, hepatitis A, HIV, lyme disease, infectious mononucleosis and pregnancy may also be positive with this test.
Results are reported to the ordering physician or health care provider as indicated on the requisition.
Specimens that are positive for syphilis serology are reported to the Medical Officer of Health as per Health Protection and Promotion Act.