''Treponema paraluiscuniculi'' is a

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wa ...

, spiral-shaped bacterium. It is the etiologic agent of "Rabbit Syphilis". This condition occurs occasionally in laboratory rabbits, pet rabbits, and wild rabbits, but is not considered a significant cause of morbidity. The organism is most commonly spread via the

venereal Human sexual activity, human sexual practice or human sexual behaviour is the manner in which humans experience and express their sexuality. People engage in a variety of sexual acts, ranging from activities done alone (e.g., masturbation) ...

route, however, extragenital contact transmission can occur. The lesions associated with ''Treponema paraluiscuniculi'' include edema,

erythema Erythema (from the Greek , meaning red) is redness of the skin or mucous membranes, caused by hyperemia (increased blood flow) in superficial capillaries. It occurs with any skin injury, infection, or inflammation. Examples of erythema not asso ...

, and

papules A papule is a small, well-defined bump in the skin. It may have a rounded, pointed or flat top, and may have a dip. It can appear with a stalk, be thread-like or look warty. It can be soft or firm and its surface may be rough or smooth. Some h ...

of the mucocutaneous junctions of the vulva, prepuce, anal region, muzzle, and periorbital region that progress to ulceration and crusting. Histologically, these areas are characterized by hyperplasia of the epidermis, necrosis of epithelial cells, erosion and ulceration, and an inflammatory infiltrate composed of

plasma cells Plasma cells, also called plasma B cells or effector B cells, are white blood cells that originate in the lymphoid organs as B lymphocytes and secrete large quantities of proteins called antibodies in response to being presented specific substan ...

macrophages Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...

, and

heterophil Neutrophils (also known as neutrocytes or heterophils) are the most abundant type of granulocytes and make up 40% to 70% of all white blood cells in humans. They form an essential part of the innate immune system, with their functions varying in ...

s. The recommended method of testing for the bacterium is skin scrape with wet mount and dark field microscopy. The organisms are also argyrophilic and will be highlighted in histologic section by a silver stain (such as Warthin-Starry). Differential diagnoses include ''

Pasturella ''Pasteurella multocida'' is a Gram-negative, nonmotile, penicillin-sensitive coccobacillus of the family Pasteurellaceae. Strains of the species are currently classified into five serogroups (A, B, D, E, F) based on capsular composition and ...

'' infection, moist

dermatitis Dermatitis is inflammation of the skin, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened. The area of skin involved can ...

, and traumatic injury.

References

{{Taxonbar, from=Q2803910 paraluiscuniculi