An epidemiological study of syphilis incognito, an emerging public health problem in Greece

Background: Syphilis incognito is a subtype of latent syphilis (early or late) characterized by no signs or symptoms of primary or secondary syphilis and diagnosed by positive serologic results for syphilis during routine screening. Objective: To study the epidemiological characteristics, causes, and implications of syphilis incognito in Greece. Patients and Methods: All new adult patients diagnosed as having syphilis in Andreas Sygros Hospital for Skin and Venereal Diseases, Athens, Greece, from 1989 through 1996 were studied prospectively and retrospectively (history, physical examination, serologic tests, cerebrospinal fluid examination, and imaging) to determine the stage of their disease. The epidemiological, clinical, and serologic characteristics of patients with syphilis incognito were recorded and analyzed. Results: During the 8-year period, 711 new syphilis cases were detected; of these, 480 cases (67.5%) fulfilled the definition criteria of syphilis incognito. The male-female ratio was 1.8:1. Patients with syphilis incognito were most commonly heterosexual, had a median socioeconomic status, and were aged 20 to 39 years, and their conditions were diagnosed during routine screening for syphilis (prenatal care, hospital admission, or blood donation). However, the number of syphilis incognito cases appeared to decline during the period studied. Conclusions: The incidence of syphilis in Greece has decreased dramatically, following the trends in western Europe. The most common form of syphilis is syphilis incognito, affecting adults who are older and have a higher socioeconomic status than those in the past. Improved hygiene and wide use of antibiotics that minimize or abolish symptoms of early disease may have contributed to the frequency of syphilis incognito in recent years. Screening of asymptomatic persons, especially those at high risk, should continue and be reenforced to prevent the devastating consequences of unrecognized and untreated syphilis.