Editor,—I read Dr Reed's letter on tertiary syphilis¹ with interest.

The regimen he describes for the treatment of early syphilis—arsenic, bismuth, and round the clock aqueous penicillin, was used in our hospital from 1946–8² although daily penicillin in beeswax was also used. It was unclear how much inactive penicillin K was in the commercial product used. The penicillin regimen used here was higher than in Lincoln (40 000–75 000 units 3–4 hourly). There were 10 treatment failures (?reinfections) out of 275 patients described.²

Treponema pallidum remains viable in the CSF even after adequate clinical treatment^{3, 4} The old adage that we achieve clinical but not microbiological cure of syphilis with antibiotics is probably true.

It is likely that most people in developed countries nowadays who have untreated syphilis have received treponemicidal antibiotics for other intercurrent infections, so that any neurosyphilis that developed would either be modified⁵ with few physical signs or would be completely treated and clinically cured. However, others disagree with this.⁶

But, to answer Dr Reed's question, we haven't seen anyone treated since the second world war who has developed neurosyphilis in subsequent years.