Treponema pallidum subsp. pallidum (etiologic agent of syphilis) / T. pallidum subsp. pertenue (etiologic agent of yaws) / T. paraluiscuniculi (also known as Treponema cuniculi)

Test code: B0010 - Ultrasensitive qualitative detection but not differentiation of Treponema pallidum suspecies pallidum and pertenue, and Treponema paraluiscuniculi, by real time PCR

Treponema is a genus of commonly found, gram-negative, spirochete bacteria.  Treponema pallidum subspecies pallidum and subspecies pertenue, along with T. paraluiscuniculi, share a nearly identical genome. It is usually not practical nor necessary to differentiate them by molecular or serological means, so their exact identification, if necessary, is usually inferred based on host species and infection site.

The oral cavity, gastrointestinal tract and vagina are the main colonization sites for bacteria of this genus. Treponema pallidum is one of the Treponema species that colonizes the vaginal area in humans and is the causative organism of syphilis. T. pallidum is a motile spirochete that is generally acquired by close sexual contact; the bacteria enter host tissue by breaches in squamous or columnar epithelium. The major symptom is a primary chancre (an area of ulceration and inflammation) in genital areas. If untreated the disease can progress to secondary and tertiary syphilis, characterized by maculopapular rashes and central nervous system involvement.

Treponema pallidum suspecies pertenue is the etiologic agent of yaws in both humans and nonhuman primates. Infection of NHPs by this subspecies appears to be widespread at least in subsaharan Africa (Chuma et al., 2018). Nonhuman primates may represent a reservoir of this pathogen, and thus the presence of Treponema infections in NHPs may be important for yaws research and One Health initiatives (Knauf et al., 2013).

Unlike T. pallidum, T. paraluiscuniculi causes venereal spirochetosis only in rabbits and is known as rabbit syphilis, vent disease, or cuniculosis. Although its genome structure is closely related to other pathogenic Treponema species including T. pallidum, T. paraluiscuniculi does not infect humans. Interestingly, T. paraluiscuniculi can also infect hares but it does not cause disease in hare species. Rabbits infected with T. paraluiscuniculi do not develop symptoms quickly; in fact a significant percentage of infected rabbits may not develop any apparent symptoms but remain as carriers. Young rabbits are especially resistant to infection. After 3-6 weeks of incubation, crusty lesions may sometimes be observed around the anus, genitals or face. These lesions can worsen to exude serum or blood.

Microscopy and serology are not useful methods to detect these bacteria due to the similarity in physical and genomic characteristics of these pathogenic bacteria with other non-pathogenic species; serological cross-reactivity with other closely related but non-pathogenic species of Treponema often gives rise to false positive serology results. Molecular detection by PCR is the method of choice to quickly and specifically identify T. pallidum and T. paraluiscuniculi (Gayet-Ageron et al., 2015). 

Utilities:

• Help confirm the disease causing agent
• Shorten the time required to confirm a clinical diagnosis of Treponema pallidum/paraluiscuniculi
• Help ensure that colonies are free of T. pallidum/paraluiscuniculi
• Early prevention of spread of T. pallidum/paraluiscuniculi among a facility
• Minimize human exposure to T. pallidum/paraluiscuniculi
• Safety monitoring of biological products that derive from susceptible animals

Specimen requirements:  0.2 ml whole blood in EDTA (purple top) tube, or 0.2 ml serum or CSF, or 0.2 ml fresh, frozen or fixed tissue, or vaginal swab or culture.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative real time polymerase chain reaction

Normal range: Nondetected