Non-treponemal tests are repeated to monitor active infection and treatment response. Titres should decline fourfold within 6 months after treatment of primary or secondary syphilis and within 12-24 months after treatment of latent or late syphilis.

Venereal Disease Research Laboratory or rapid plasma reagin titres should be measured monthly after treatment for 3 months, and then every 3 months thereafter. The same non-treponemal test should be used sequentially when monitoring treatment response. This is because results obtained from one test are not directly comparable with that of the other, non-treponemal test.

With effective treatment, non-treponemal tests should become negative. However, some patients who have received adequate treatment become serofast, maintaining a low-level positive titre. This is their baseline titre from which re-infection is assessed.

Following treatment for neurosyphilis, cerebrospinal fluid (CSF) examination should be repeated every 6 months until the white blood cell (WBC) count is normal (if elevated on the initial sample). Re-treatment is considered if the WBC count has not decreased after 6 months or if the CSF remains abnormal after 2 years.[5]

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