Pathogen Safety Data Sheets: Infectious Substances – Treponema pallidum

SECTION I - INFECTIOUS AGENT

NAME: Treponema pallidum

SYNONYM OR CROSS REFERENCE: Venereal syphilis, endemic syphilis, bejel in Arabic, dichuchwa in Bechuanaland (Botswana), njovera in Zimbabwe, yaws in Carib, frambesia (raspberry) in Latin, pian in French, bouba in Portuguese, malinica in Polish, Lues, Treponema pallidum pallidum, Treponema pallidum endemicum, Treponema pallidum pertenue

CHARACTERISTICS: Treponema pallidum is a spirochete bacterium belonging to the Spirochaetaceae family. The three subspecies (Treponema pallidum pallidum, Treponema pallidum endemicum, and Treponema pallidum pertenue) are all morphologically indistinguishable and have an approximate diameter of 0.18 µm and length of 6-20 µm. It can not be cultured on bacteriological media ^{Footnote 1}. T. pallidum pallidum causes venereal syphilis, T. pallidum endemicum causes endemic syphilis, and T. pallidum pertenue causes yaws. It is debated whether T. carateum (the causative agent of the skin disease pinta) is also a subspecies ^{Footnote 2Footnote 3}.

SECTION II - HAZARD IDENTIFICATION

PATHOGENICITY/TOXICITY: Venereal syphilis has primary, secondary, latent, and tertiary stages. The infection can be lifelong if left untreated ^{Footnote 2}. Clinical manifestations of the primary stage include one or many chancres (painless indurated ulcers with a serous exudate) on skin or mucous membranes, and regional lymphadenopathy ^{Footnote 3}. Clinical manifestations of the secondary stage include a symmetric maculopapular rash involving the palms and soles, generalized lymphadenopathy, fever, malaise, raised lesions (condylomata lata), and alopecia ^{Footnote 3}. Primary and secondary syphilis generally resolve spontaneously a few weeks after onset ^{Footnote 3}. Tertiary syphilis may develop in one third of untreated patients, and can cause severe morbidity and death ^{Footnote 3}. Tertiary syphilis may include gummatous syphillis where gummatous lesions may form on any organ or tissue, cardiovascular syphilis, which usually manifests as aortic disease and neurosyphillis ^{Footnote 3}. Neurosyphilis can manifest as acute syphilitic meningitis, meningovascular syphilis or as paresis or tabes doraslis.  It usually arises in tertiary syphilis, but can occur as early as 3 months post infection ^{Footnote 3}. Over 40% of patients with secondary syphilis experience some central nervous system involvement ^{Footnote 3}.  Congenital syphilis can result in abortion, stillbirth, prematurity, and birth defects ^{Footnote 2}.

Endemic syphilis has primary, secondary, latent and late stages ^{Footnote 3}. Clinical manifestations of primary endemic syphilis include mucosal or cutaneous lesions that often go undetected ^{Footnote 3}. Clinical manifestations of the secondary stage include multiple oropharyngeal and cutaneous lesions, generalized lymphadenopathy, and periostitis ^{Footnote 3}. Clinical manifestation of the late stage includes destructive lesions of the skin, bone and cartilage ^{Footnote 3}. Unlike venereal syphilis, endemic syphilis rarely causes cardiovascular or neurologic disease.

Yaws has an early, latent and late stage. The early stage manifests as a primary lesion (mother yaw), disseminated lesions (daughter yaws), malaise, fever, lymphadenopathy, osteitis, and periostitis ^{Footnote 3}. The late stage of yaws develops in 10 % of cases, and presents as hyperkeratotic skin lesions, and destructive lesions of bone and cartilage including rhinopharyngitis mutilans ^{Footnote 2}. Onset of yaws usually occurs during childhood (before the age of 15)^{Footnote 2Footnote 3}.

The latent stages of yaws, venereal syphilis, and endemic syphilis are characterized by positive serological tests, without any symptoms ^{Footnote 3}.

EPIDEMIOLOGY: Venereal syphilis (T. pallidum pallidum) has a worldwide distribution but varies between geographic locations and socioeconomic groups ^{Footnote 3}. It is more common in people aged 20-45 ^{Footnote 4}. There are an estimated 12 million new cases per year; and 34,270 cases were reported in 2003 ^{Footnote 3}. Endemic syphilis (T. pallidum endemicum) is restricted to desert and temperate regions of North Africa and the Middle East. Yaws (T. pallidum pertenue) is distributed mainly in tropical and desert regions of Africa, South America, and Indonesia ^{Footnote 3}. There are an estimated 460,000 new cases of non-venereal syphilis a year ^{Footnote 3}.

HOST RANGE: Humans ^{Footnote 3}

INFECTIOUS DOSE: 57 organisms by injection ^{Footnote 5}

MODE OF TRANSMISSION: All subspecies of Treponema pallidum can be transmitted through direct contact with active lesions ^{Footnote 3}. Venereal syphilis is also spread through sexual contact and through the placenta barrier. Endemic syphilis is transmitted through contact with mucous membranes. Yaws is spread through contact with skin lesions and possibly through drinking vessels.

INCUBATION PERIOD: Primary venereal syphilis has an incubation of 10-90 days, although it is usually 21 days ^{Footnote 3}. Secondary venereal syphilis usually arises 6 weeks to 6 months post infection ^{Footnote 3}.  Tertiary venereal syphilis has its onset months to years after initial infection ^{Footnote 3}. Early congenital syphilis arises in under two years, and is considered late congenital syphilis if it persists longer than two years ^{Footnote 3}. Early stage yaws onset is usually 9-90 days post infection, with an average of 21 days ^{Footnote 3}. The primary stage of endemic syphilis arises approximately 2 to 4 weeks after inoculation. Secondary stage occurs 3 to 6 months post-inoculation and tertiary stage occurs as early as 6 months or as late as several years after initial symptoms ^{Footnote 6}.

COMMUNICABILITY: Treponema pallidum is transmitted by direct contact with active lesions; healed lesions are not infective ^{Footnote 3}. T pallidum pallidum is also spread through sexual contact, and from a pregnant mother to her child. T pallidum endemicum is also communicable through mucous membrane contact, and is occasionally transmitted vertically.

SECTION III – DISSEMINTATION

RESERVOIR: Humans. Treponema pallidum are obligate parasites and are not known to have any non-human or environmental reservoirs ^{Footnote 3}.

ZOONOSIS: None.

VECTORS: None.

SECTION IV – STABILITY AND VIABILITY

DRUG SUSCEPTIBILITY: Susceptible to penicillin, tetracycline, doxycycline ceftriaxone, chloramphenicol, and erythromycin ^{Footnote 2Footnote 7Footnote 8}.

DRUG RESISTANCE: Treponema pallidum has increasing resistance to azithromycin^{Footnote 9}. There have been a few reports of clinical failures with penicillin in Papua New Guinea and Ecuador ^{Footnote 2}.

SUSCEPTIBILITY TO DISINFECTANTS: Susceptible to 70% ethanol, 2% glutaraldehyde, 1% sodium hypochlorite ^{Footnote 10-12}.

PHYSICAL INACTIVATION: Inactivated by 50 minutes at temperatures of 56°C ^{Footnote 13}. Susceptible to UV light (120 J) ^{Footnote 12}.

SURVIVAL OUTSIDE HOST: Treponema pallidum can survive 120 hours or more in blood at 4°C (although this varies by concentration of treponemes) ^{Footnote 14}.

SECTION V – FIRST AID / MEDICAL

SURVEILLANCE: Monitor for symptoms and confirm infection by serological methods. Darkfield microscopy and direct fluorescent antibody stains can be used to detect Treponema pallidum in lesion exudates, lymph node aspirate, and tissue biopsies ^{Footnote 8}. A fluorescent treponemal antibody absorption test, Rapid Plasma Reagin or T. pallidum particle agglutination test can be used to analyse blood. Cerebrospinal fluid can be analysed with a fluorescent treponemal antibody absorption test ^{Footnote 8}. Serological tests may detect current, recent, or past infection ^{Footnote 2}.

Note: All diagnostic methods are not necessarily available in all countries.

FIRST AID/TREATMENT: Penicillin provides the most effective treatment for all stages of disease cause by Treponema pallidum ^{Footnote 7}. Those who are allergic to penicillin can take tetracycline, doxycycline, or erythromycin ^{Footnote 2}. Ceftriaxone may be considered as an alternative for treatment of early syphilis in pregnancy ^{Footnote 7}. Chloramphenicol may also be used to treat neurosyphilis ^{Footnote 8}.

IMMUNIZATION: None.

PROPHYLAXIS: Yes, Benzathine penicillin G, ceftriaxone, or azithromycin ^{Footnote 15}.

SECTION VI – LABORATORY HAZARDS

LABORATORY-ACQUIRED INFECTIONS: As of 1995, 15 cases of infection from Treponema pallidum were reported ^{Footnote 16}.

SOURCE/SPECIMENS: Lesion exudates, semen, vaginal secretions, blood products, lymph node aspirates, cerebrospinal fluid, saliva, milk of lactating females ^{Footnote 2Footnote 8Footnote 17-19}.

PRIMARY HAZARDS: Accidental parenteral inoculation, contact with nonintact skin or mucous membranes, inhalation of aerosols ^{Footnote 16}.

SPECIAL HAZARDS: None

SECTION VII – EXPOSURE CONTROLS / PERSONAL PROTECTION

RISK GROUP CLASSIFICATION: Risk Group 2 ^{Footnote 20}

CONTAINMENT REQUIREMENTS: Containment Level 2 facilities, equipment, and operational practices for work involving infectious or potentially infectious materials, animals, or cultures.

PROTECTIVE CLOTHING: Lab coat. Gloves when direct skin contact with infected materials or animals is unavoidable. Eye protection must be used where there is a known or potential risk of exposure to splashes ^{Footnote 21}.

OTHER PRECAUTIONS: All procedures that may produce aerosols, or involve high concentrations or large volumes should be conducted in a biological safety cabinet (BSC). The use of needles, syringes, and other sharp objects should be strictly limited. Additional precautions should be considered with work involving animals or large scale activities ²¹.

SECTION VIII – HANDLING AND STORAGE

SPILLS: Allow aerosols to settle and, wearing protective clothing, gently cover spill with paper towels and apply an appropriate disinfectant, starting at the perimeter and working towards the centre. Allow sufficient contact time before clean up.

DISPOSAL: Decontaminate all wastes that contain or have come in contact with the infectious organism before disposing by autoclave, chemical disinfection, gamma irradiation, or incineration.

STORAGE: The infectious agent should be stored in leak-proof containers that are appropriately labelled.

SECTION IX – REGULATORY AND OTHER INFORMATION

REGULATORY INFORMATION: The import, transport, and use of pathogens in Canada is regulated under many regulatory bodies, including the Public Health Agency of Canada, Health Canada, Canadian Food Inspection Agency, Environment Canada, and Transport Canada. Users are responsible for ensuring they are compliant with all relevant acts, regulations, guidelines, and standards.

UPDATED: September 2011

PREPARED BY: Pathogen Regulation Directorate, Public Health Agency of Canada

Although the information, opinions and recommendations contained in this Pathogen Safety Data Sheet are compiled from sources believed to be reliable, we accept no responsibility for the accuracy, sufficiency, or reliability or for any loss or injury resulting from the use of the information. Newly discovered hazards are frequent and this information may not be completely up to date.

Copyright © Public Health Agency of Canada, 2011 Canada