Syphilis, secondary
2026 Case Definition

Background

A stage of infection with T. pallidum that reflects systemic dissemination and is characterized by a wide variety of signs or symptoms.

Clinical Criteria

In the absence of a more likely alternative diagnosis, meets at least one of the following signs^††‡‡:

• Localized or diffuse body rash classically described as copper-colored lesions that can be any combination of macular, papular, squamous, or pustular in appearance and typically involve the chest, back, palms of the hands, and/or soles of the feet, OR
• Mucous patches, OR
• Condylomata lata, OR
• Patchy alopecia that is often described as “moth-eaten” in appearance.

^††The primary ulcerative lesion may still be present.

^‡‡Given that syphilis is often referred to as “the great imitator”, this list is not exhaustive, and signs and symptoms may be nonspecific (e.g., secondary syphilis with visceral organ manifestations).

Laboratory Criteria

Confirmatory Laboratory Evidence:

Meets at least one of the following criteria:

• Direct detection of T. pallidum by darkfield microscopy in a specimen that was both not obtained from the oropharynx and not potentially contaminated by stool, OR
• Direct detection of T. pallidum by IHC staining in a specimen that was both not obtained from the oropharynx and not potentially contaminated by stool, OR
• Direct detection of T. pallidum by nucleic acid amplification test (e.g., PCR, LAMP) or a diagnostically equivalent molecular method in any specimen.

Presumptive Laboratory Evidence:

• A current (i.e., a test performed in the context of this index presentation) reactive blood-based nontreponemal antibody test (i.e., VDRL, RPR, point-of-care, or equivalent nontreponemal method), AND
• A reactive blood-based treponemal antibody test (i.e., TP-PA, EIA, CIA, MFI or MIA, FTA-ABS, point-of-care, or equivalent treponemal method)^¶.

Supportive Laboratory Evidence:

• A current (i.e., a test performed in the context of this index presentation) reactive blood-based nontreponemal antibody test (i.e., VDRL, RPR, point-of-care, or equivalent nontreponemal method) with a titer that is greater than or equal to 1:32, AND
• No evidence of a concurrent nonreactive blood-based treponemal antibody test.

Note: The categorical labels used here to stratify laboratory evidence are intended to support the standardization of case classifications for public health surveillance. The categorical labels should not be used to interpret the utility or validity of any laboratory test methodology.

^¶Current or historical reactive treponemal antibody tests can be used to satisfy this criterion.

Probable

• Meets clinical criteria AND either:
  • Meets presumptive laboratory evidence, OR
  • Meets supportive laboratory evidence.

Confirmed

• Meets clinical criteria AND meets confirmatory laboratory evidence.

• Syphilis (Treponema pallidum) | 2026 Case Definition