Syphilis

Victorian statutory requirement

Syphilis (Group C disease) must be notified in writing within five days of diagnosis.

Specific information must be notified under the Public Health and Wellbeing Regulations 2009. To maintain confidentiality, only the name code (first two letters of the surname followed by the first two letters of first name) is required. A questionnaire is sent to the diagnosing doctor to collect additional information on the case that is essential for detecting disease trends and informing policy development.

Medical practitioners have a statutory obligation under the Children and Young Persons Act 1989 to notify the Department of Human Services Child Protection service if they believe that a child is in need of protection on the basis of sexual abuse.

Infectious agent

The spirochaete Treponema pallidum, subspecies pallidum is the infective agent.

Identification

Clinical features
Syphilis is characterised by a primary lesion, a secondary eruption involving skin and mucous membranes, long periods of latency, and late lesions of skin, bone, viscera, cardiovascular and central nervous systems.

The stages of syphilis can be divided into:

early syphilis where primary (chancre), secondary (rash or condylomata lata) or latent syphilis (asymptomatic) of less than two years duration exist based on serology results
late latent syphilis where latent syphilis has existed for two or more years or of indeterminate duration, in the absence of neurosyphilis and other symptoms and signs of disease
tertiary syphilis where cardiovascular involvement and neurosyphilis is present.

Syphilis in pregnancy
Foetal infection may result in abortion, stillbirth, premature delivery and perinatal death. In congenital syphilis, generalised systemic disease in a live born infant is present.

Method of diagnosis
Syphilis can be diagnosed by the demonstration of spirochaetes in the exudate from primary chancres or from the mucous membrane lesions of secondary syphilis, using dark field microscopy or immunofluorescence.

Dark field microscopy is a difficult technique and requires an experienced operator for reliable results. The test is unreliable on mucous membrane lesions due to the presence of morphologically similar saprophytic spirochaetes. Dark field is also best done on site, as drying of the exudate during transport to the laboratory renders the specimen unsuitable for microscopy.

Immunofluorescence is more sensitive and does not have to be performed immediately. It is suitable for use with mucous membrane lesions but it is not currently performed by the Victorian Infectious Diseases Reference Laboratory.

More commonly syphilis is diagnosed using a combination of treponemal and non-treponemal serological tests:

Treponemal tests measure specific treponemal antibodies in serum. These include Treponema pallidum particle agglutination, enzyme immunoassay and fluorescent Treponemal antibody absorption tests. Once these tests are reactive they usually remain so for life and give no indication of current disease activity. Enzyme immunoassays with highly purified Treponema pallidum antigens are becoming more commonly used for screening for syphilis. These assays have a high specificity and sensitivity. IgM enzyme immunoassay for the detection of IgM antibodies to Treponema pallidum is a useful assay for the diagnosis of congenital syphilis.
Non-treponemal tests such as rapid plasma reagin (RPR) and venereal diseases research laboratory test measure antibodies that are produced in response to syphilis and also to a relatively large number of other conditions. This results in biological false positives. The non-treponemal test gives an indication of current disease activity.

All sera showing reactive serology on screening tests should be forwarded to a reference laboratory for confirmatory testing.

It is necessary to interpret syphilis serology in the context of:

clinical history and examination
serial RPR titres tested in parallel where possible (results obtained from different laboratories are not directly comparable)
treponemal test results
a past record of treatment.

It is essential that all cases of syphilis receive close clinical and laboratory follow-up.

Lumbar puncture is advised when there are:

neurological or ophthalmic signs or symptoms
evidence of active tertiary syphilis
treatment failure
HIV infection with late latent syphilis or syphilis of unknown duration.

Note that other sexually transmissible infections may be present in addition to syphilis.

Patients in whom syphilis is diagnosed should be encouraged to be tested for HIV infection.

Incubation period

The incubation period is from ten days to three months and is usually three weeks.

Public health significance & occurrence

This is a complex disease. Sequelae include neurosyphilis, cardiovascular syphilis and congenital infection with foetal death, stillbirth and abortion. Testing and effective treatment are available to facilitate the interruption of disease transmission. Immune responses are only partially protective and reinfection may occur following treatment. Syphilis enhances the transmission of HIV, like other diseases that cause genital ulcers.

The number of notifications of infectious syphilis in Victoria is currently relatively small. However, syphilis occurs worldwide and has a high incidence in other parts of Australia. Other developed countries have experienced recent outbreaks. Imported infectious cases could result in syphilis re-emerging as a significant public health issue.

Reservoir

Humans are the only reservoir.

Mode of transmission

Transmission occurs primarily by sexual contact. Transplacental infection of a foetus may occur during the pregnancy of an infected woman. Foetal infection occurs with high frequency in untreated early infections of pregnant women and with lower frequency later in the disease or in late latency. Syphilis may also be transmitted by transfusion of blood from infected individuals, however this risk is minimised by the screening of all donated blood in Australia.

Period of communicability

A case is considered sexually infectious until the end of the early latent period which is approximately two years after infection. Infectious moist mucocutaneous lesions are present in the primary and secondary stages of syphilis and may reoccur intermittently in the early latent period. These lesions may not be apparent to the infected individual.

Susceptibility & resistance

Everyone is susceptible to infection.

Control measures

Preventive measures
Education about safe sex practices including the use of condoms and early detection of infection by testing of people at risk are the main prevention measures.

Control of case
Penicillin is the drug of choice to treat syphilis.

Further information on the clinical management of patients with syphilis can be found in the latest editions of the Therapeutic guidelines: antibiotic (Therapeutic Guidelines Limited) and the National management guidelines for sexually transmissible infections (Venereology Society of Victoria, 2002).

The necessity for long term follow-up with repeat serology and the frequent presence of complicating factors makes it desirable to seek specialist advice.

Control of contacts
Sexual contacts should be identified. The extent of contact tracing depends on the clinical stage of infection.

For primary syphilis, all persons having sexual contact with the index case during the three months preceding onset should be evaluated. Such contacts should be treated as for the case, even if their serology is negative.

For secondary syphilis, this period should be extended to six months and for early latent syphilis, to twelve months.

For late latent syphilis, any sexual partners and also children of infected women should be evaluated.

For congenital syphilis, all members of the immediate family should be evaluated.
Contact tracing assistance can be provided by the Departments partner notification officers Telephone: (61 3) 9347 1899.

All newborns of mothers with syphilis should be investigated and treated in consultation with a specialist.

Control of environment
Not applicable.

Outbreak measures

Not applicable.

Additional sources of information

Australian Government Department of Health and Family Services 1997, Contact tracing manual a practical handbook for health care providers managing people with HIV, viral hepatitis, other STDs and HIV-related tuberculosis, Australian Government Department of Health and Family Services.
Centers for Disease Control and Prevention 2002, Sexually transmitted diseases treatment guidelines 2002, Morbidity and Mortality Weekly Report, vol. 51, RR06, pp.180.
www.cdc.gov/mmwr
Egglestone, SI et al 2000, Serological diagnosis of syphilis, Communicable Diseases & Public Health, vol. 3, no. 3, pp. 15862.
Larsen, SA et al 1995, Laboratory diagnosis and interpretation of tests for syphilis, Clin Micro Revs, vol. 8, no. 1, pp. 121.
Nganampa Health Council 1999, How to interpret syphilis results A manual for nursing and medical staff in remote area clinics, 2nd ed.
Singh, AE et al 1999, Syphilis: Review with emphasis on clinical, epidemiologic and some biologic features, Clin Micro reviews vol. 12, no. 2, pp. 187209.
Venereology Society of Victoria 2002, National management guidelines for sexually transmissible infections
www.mshc.org.au

Infectious diseasesepidemiology and surveillance

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