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Microbiology · Spirochetes and spiral bacteria (Treponemes/syphilis, Borrelia/Lyme disease and relapsing fevers, Leptospira, Campylobacters, Helicobacters)

Non-venereal treponematoses

Treponematoses non venereae

Non-venereal treponematoses are a group of infectious diseases caused by pathogenic spirochetes of the species Treponema pallidum (specific subspecies) and Treponema carateum. Despite biological and clinical similarities to classic syphilis, these infections are transmitted primarily via non-sexual contact and occur in strictly defined geographical regions.

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PathogensT. pallidum subspecies and T. carateum species
EndemicityTropics, Africa, Middle East, and Asia
TreatmentPenicillin antibiotics
DiagnosticsSimilar to syphilis detection methods
3 min readFor medical studentsUpdated Sep 25, 2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

General characteristics

The group of non-venereal treponematoses encompasses infections that share significant similarities with classic syphilis, yet differ fundamentally in their transmission mechanisms and geographical distribution. The causative agents are specific subspecies of the pale treponema, as well as the related species T. carateum. The main feature of these pathologies is the absence of sexual transmission as the primary route.

Bejel (endemic syphilis)

The disease is caused by Treponema pallidum subspecies endemicum. The infection is prevalent in the Middle East, the African continent, and Southeast Asia.

Features of infection:

  • Transmission: occurs exclusively via direct contact and household transmission.
  • Clinical presentation: initially, the infection manifests as a characteristic rash affecting the skin and mucous membranes. In later stages of the disease, severe lesions develop that visually and clinically resemble gummata typical of tertiary syphilis.
Test your knowledge on this topicAssignments from the Microbiology course bank — instant answers and explanations.

Yaws (tropical granuloma)

The causative agent of tropical granuloma is Treponema pallidum subspecies pertenue. The disease is endemic to the tropical regions of both hemispheres.

An epidemiological feature of yaws is the tendency to form familial outbreaks. The infection is transmitted both through household items and via skin-to-skin contact.

Disease progression:

  1. A painful ulcer forms at the site of pathogen entry (the portal of entry).
  2. Subsequently, the process becomes generalized, accompanied by profuse skin eruptions.
  3. The ultimate outcome of the infection is a transition into severe dystrophic processes affecting not only the skin, but also bone tissue.

Pinta

Unlike the previous nosologies, pinta is caused by a distinct species — Treponema carateum. The infection occurs predominantly in individuals with dark skin living in the tropical belt of the Western Hemisphere.

The pathogen can be transmitted through contact as well as vector-borne transmission via insect bites (specifically, blackflies).

Symptomatology: the primary lesion at the portal of entry is a papule. Upon generalization of the process, pronounced hyperkeratosis of the soles and palms is observed, along with pathological hair loss.

Patient Management Principles

Approaches to the diagnosis and therapy of non-venereal treponematoses are standardized and rely on the treatment protocols for classic syphilis:

  • Diagnostics is performed using the same laboratory methods and tests as for the detection of venereal syphilis.
  • Treatment is based on the administration of penicillin antibiotics, to which pathogenic treponemes remain highly sensitive.

Briefly: answers to topical questions

What specific serological reactions are used for the laboratory diagnosis of non-venereal treponematoses?

For the laboratory diagnosis of non-venereal treponematoses, the same methods are used as for syphilis, including a complex of non-treponemal and treponemal tests.

  • Non-treponemal tests — VDRL (venereal disease research laboratory) test and RPR (rapid plasma regain) test.
  • Treponemal tests — ELISA (enzyme-linked immunosorbent assay), TPHA / TPPA (treponema pallidum hemagglutination assay), FTA-ABS (fluorescent treponemal antibody absorption), TPI (treponema pallidum immobilization test), WB (western blot), CLIA, and CIA.

Treponemal tests have high sensitivity but yield cross-reactions with the causative agents of yaws and bejel.

What specific bone lesions develop in the late stages of yaws?

In the late stages of yaws, dystrophic bone processes develop. Specific bone lesions are not detailed, but it is noted that the outcome of the disease is a transition into dystrophic processes of the skin and bones. Meanwhile, late lesions in another non-venereal treponematosis — bejel — resemble gummata in syphilis.

What are the morphological and tinctorial properties of the causative agents of non-venereal treponematoses?

Sources describe members of the genus Treponema as thin, corkscrew-twisted filaments with 8–12 small, uniform coils. The causative agents of non-venereal treponematoses include T. pallidum subspecies endemicum and pertenue, as well as T. carateum. The morphological properties of T. carateum and the tinctorial properties of the pathogens are not described in the sources.

How to memorize

To avoid confusing the pathogens: Endemic syphilis — endemicum, Yaws (Tropical) — pertenue (T and P close together), Pinta — carateum (Pinta Carate).

Class and exam questions

How do non-venereal treponematoses differ from venereal syphilis?

The main differences lie in the routes of transmission (predominantly contact-based or vector-borne) and strict geographical restriction to the tropics, Asia, or Africa.

What methods are used for the laboratory diagnosis of these infections?

Absolute identical diagnostic methods and algorithms are applied as in the detection of classic syphilis.

What is the outcome of untreated yaws?

The infection progresses to a chronic stage with the development of severe dystrophic skin and bone processes.

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What else to study on this topic

  • Pathogenesis of gumma formation in late-stage bejel
  • Mechanism of dystrophic bone lesions in yaws
  • The role of blood-sucking insects (blackflies) in the vector-borne transmission of pinta
  • Epidemiological factors contributing to familial outbreaks of yaws
  • Differential diagnosis of rash in various types of treponematoses

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