Definition
The consensus synthesizes the views of national and international experts and defines syphilis serofixation as a patient with syphilis who has undergone standardized anti-syphilis treatment and adequate follow-up (1 year for stage I syphilis, 2 years for stage II syphilis, and 3 years for advanced syphilis) and whose non-syphilis spirochete serologic test has remained at a certain titer (usually 1 : 8 or less, but more than 1 : 8 is not uncommon) for more than 3 months, excluding reinfection, neurological Syphilis serum fixation is considered when re-infection, neurosyphilis, cardiovascular syphilis and biological false positives are excluded.
Epidemiology
The consensus points to a high prevalence of serofixation of syphilis: 3.80% ~ 15.20% for stage I syphilis, 11.64% ~ 35.80% for stage II syphilis, 45.02% ~ 45.90% for stage III syphilis, and 27.41% ~ 40.50% for latent syphilis. This shows that serum fixation of syphilis has become a more difficult clinical problem.
Pathogenesis
The possible mechanisms of syphilis serofixation, as summarized by consensus, include: alteration of syphilis spirochete membrane peptide antigens, lipoproteins and genes leading to failure of immune clearance, abnormal immunity, including immune imbalance and immunosuppression, and disturbance of T cell subsets, NK cells and cytokine secretion.
Prognosis
The consensus is that a persistent positive serologic response to syphilis has mainly psychological and psychiatric effects on the patient. However, there is insufficient evidence to assess the risk of syphilis serofixation, whether it causes physical damage, whether it increases the risk of relapse or progression to advanced syphilis, and whether it is beneficial for additional penicillin therapy.
Treatment pathway
Consensus has resulted in treatment norms for syphilis serofixation, including
1. a detailed history at the time of initial syphilis treatment, including history of sexual contact (time of infection, syphilis infection status of sexual partners, recent risky sexual behavior, etc.), history of previous treatment (time of initiation of treatment, type of drug used, duration and dosage, follow-up, etc.), in order to anticipate the patient’s post-treatment serologic response
2. During follow-up, cerebrospinal fluid examination is recommended to exclude neurosyphilis for those identified with syphilis serofixation, repeatedly if necessary. HIV testing should also be performed to rule out HIV infection. Cardiovascular syphilis and other visceral syphilis should also be excluded by appropriate testing. False-positive syphilis serology should also be excluded.
3. Patients with serum fixation of syphilis need to be analyzed and counseled.
4. Patients who have received adequate anti-syphilis treatment and adequate follow-up, if there is no recurrence of clinical symptoms, neurological examination, cerebrospinal fluid examination and other relevant tests to exclude neurological and other visceral systemic damage, and if the non-syphilis spirochete serology test maintains a low titer of 1:8 or less for a long period of time, treatment is not necessary, but regular follow-up (usually every 6 months) is required.
It is recommended to add syphilis spirochete-specific IgM antibody testing at follow-up if available, which can be used as a marker for syphilis recurrence and reinfection. A 4-fold or higher increase in the titer of the non-syphilis spirochete serology test during follow-up indicates recurrence or reinfection and requires re-treatment.
Patients with syphilis serostasis need to weigh the pros and cons of pregnancy, and if pregnant, they need to be followed up regularly and, if necessary, preventive treatment can be considered, i.e., treatment of syphilis in pregnancy according to the norms for syphilis in pregnancy. Studies have shown that treatment of pregnant syphilis patients with a standardized anti-syphilis regimen can block congenital syphilis in 98.5% to 100% of cases.
From the Chinese Journal of Dermatology, Vol. 48, No. 11.