Spirochetes: Treponema, Borrelia, and Leptospira

Vocabulary terms and definitions covering the spirochete genera Treponema, Borrelia, and Leptospira, their clinical stages, manifestations, diagnostics, and associated diseases.

Paraplasmic flagella

Flagella located within the membrane of spirochetes that allow them to move in a characteristic screw-like motion.

Treponema pallidum subspecies pallidum

The microaerophilic spirochete that acts as the causative agent of syphilis (the great pox), has a generation time of about $30\text{ hours}$, and has humans as its only host.

Pox

A fluid-filled lesion characteristic of diseases such as the great pox (syphilis).

Primary syphilis

The initial stage of syphilis characterized by regional lymphadenopathy and the development of a hard, painless chancre at the site of inoculation lasting $3$ to $6\text{ weeks}$.

Lymphadenopathy

Swollen lymph nodes in the area of draining lymph nodes resulting from the activation of adaptive immune cells.

Secondary syphilis

The second stage of syphilis characterized by flu-like signs and symptoms followed by a non-itchy red or brown diffuse rash that frequently includes the palms of the hands and the soles of the feet.

Candeloma lata

Moist, knob-like lesions that develop in warm or moist areas of the body, such as the groin, labia, or armpits, during secondary syphilis.

Jericho Herxheimer reaction

A common reaction occurring in $50\%$ to $80\%$ of secondary syphilis patients within $2$ to $8\text{ hours}$ after receiving penicillin, caused by the release of lipoproteins, which exacerbates the rash and clears within $24\text{ hours}$.

Tertiary syphilis

The late preclinical stage developing years or decades later in approximately $30\%$ of untreated individuals, featuring destructive complications such as gummas, cardiovascular damage, aneurysms, or neurosyphilis.

Gummas

Necrotic lesions surrounded by inflammation that contain large amounts of Treponema pallidum subspecies pallidum, appearing during tertiary syphilis.

Congenital syphilis

Infection resulting when Treponema pallidum crosses the placenta into a developing fetus, which can lead to stillbirth, nasal discharge, bone deformation, and dental anomalies.

Hutchinson's teeth

Misshapen, deformed teeth that develop irreversibly in children affected by untreated congenital syphilis.

Raggities

Deep crevices that form typically near the mouth or anus in infants with congenital syphilis.

RPR and VDRL

Serological screening tests (Rapid Plasma Reagin and Venereal Disease Research Laboratory) used to detect antibodies produced against cardiolipin.

Cardiolipin

A lipid substance found on Treponema pallidum and host tissue cells against which antibodies are measured in non-treponemal serological tests.

Benzathine penicillin

The standard single-shot antibiotic treatment for syphilis infections of less than one year duration, prioritized during shortages for pregnant women and congenitally infected infants.

Treponema pallidum subspecies anemicum

The causative organism of bejel, a deforming childhood infection of the mouth, nasal cavity, body, and hands found in parts of the Middle East and North Africa.

Treponema pallidum subspecies patinae

The causative agent of yaws, which enters through skin cuts to produce primary ulcers, secondary lesions, and irreversible bone deformation.

Saber shins

An irreversible skeletal deformation where the shin bone is bowed outward, seen in patients with untreated yaws or tertiary syphilis.

Treponema keratium

The non-syphilitic spirochete responsible for pinta, a disease producing depigmented scars and long-term skin discoloration without invading deep into tissues.

Treponema denticola

An oral spirochete that colonizes beneath the gums, possessing adhesins, outer sheath peptidases to break down host immune peptides, and pore-forming proteins that damage cells.

Borrelia burgdorferi and Borrelia mayonii

The two species of the genus Borrelia recognized in the Americas as causative agents of Lyme disease, both transmitted by hard ticks in the genus Ixodes.

Erythema migrans

A bull's-eye rash that manifests at the site of the tick bite in $50\%$ to $70\%$ of individuals with Lyme disease.

Outer surface proteins (OSPs)

Surface proteins on relapsing fever Borrelia that the bacteria periodically switch via promoter regulation to evade host adaptive immunity and cause recurrent cycles of fever.

Genus Leptospira

Very thin, spiral-shaped obligate aerobic spirochetes commonly possessing a hook at one or both ends, harbored by small animal reservoirs and transmitted via contaminated water.

Bile disease

A severe complication of Leptospira infection characterized by high fever, headache, vasculitis, myocarditis, jaundice, and renal and hepatic dysfunction.