Complicated Syphilis May be More Common Than Previous Estimates Suggest

Background:  Symptomatic neurosyphilis is considered to be a rare complication of syphilis, (1.2-1.7% of cases), but to our knowledge, no contemporary studies have sought to actively identify symptoms of neurologic, otologic or ocular complications in a population-based sample. 

Methods:  Our program has asked all persons with syphilis about symptoms of complicated infections (changes in vision, hearing or tinnitus) as part of routine case investigations since 2/2012.  Disease intervention specialists (DIS) query patients about symptoms using a standardized protocol and interview form.  To determine the prevalence of symptoms, we reviewed cases reported from 3/1/2012 - 9/30/2013 that met one of the following criteria (mutually exclusive and hierarchical as listed): 1) neurosyphilis reported by the diagnosing provider, 2) partner services record indicating neurologic symptoms, 3) treatment with a regimen effective for neurosyphilis, or 4) a record of cerebrospinal fluid (CSF) testing. We assumed that remaining cases had no symptoms of complicated syphilis. We separately analyzed a strict definition of symptomatic neurosyphilis, including only symptomatic cases with documented abnormal CSF results.

Results:  A total of 573 syphilis cases were reported; 68 (11.9%) met review criteria [by criterion listed in Methods as follows: 1) N=33; 2) N=20; 3) N=4; 4) N=11].  We excluded from the symptom prevalence calculation 1 case of congenital syphilis and 3 cases for which we could not obtain symptom data.  Of the 569 remaining cases, 46 (8.1%) were associated with symptoms suggesting complicated syphilis.  Most commonly reported were vision changes (5.1%), followed by hearing changes (3.9%), tinnitus (2.7%), and other symptoms (0.7%).  The distribution of symptoms was similar when we restricted the analysis to symptoms ascertained by diagnosing providers.  Using the strict definition, 18 of 573 (3.1%) had symptomatic neurosyphilis.

Conclusions:  Our results suggest that symptomatic neurosyphilis and symptoms suggestive of complicated syphilis are more common than previously estimated.