Sexually Transmitted Diseases Services
Surveillance System
Contents
The surveillance unit of Sexually Transmitted Diseases (STD)
Services collects information on the following notifiable diseases:
The primary purpose of surveillance is to direct statewide prevention
and control activities. Important priorities are to determine the
magnitude of the problem and current dynamics of disease transmission.
The information gained is used to:
-
enable epidemiologic analysis to inform policy decisions
-
determine the level of ongoing transmission
-
assess the burden of disease in the community
-
monitor the level of testing in the community.
To facilitate
-
investigation of cases where
the mechanism of exposure is unclear
-
definition of the epidemiology of new infections
-
contact tracing/partner notification
-
identification of clusters associated with modes of transmission
which may require specific public health interventions.
Chlamydia, gonorrhoea, syphilis, and donovanosis are listed as notifiable diseases
under the provisions of the Public and Environmental Health (P&EH) Act
1987. Sections 30 and 41 of the act allow for further investigation of
cases when necessary.
The controlled notifiable diseases, HIV, AIDS,
hepatitis C and hepatitis B, are subject to the provisions of sections
31-34 of the act, these allow the Health Commission to require individuals
to undergo examination or even confine cases if there is a threat to
public health. The use of these powers under the act are subject to
magisterial oversight and there is a right of appeal to the Supreme Court.
Persons with a controlled notifiable disease are also obliged to take
reasonable measures to prevent transmission to others.
The
Public
& Environmental Health Act (1987)
as amended, provides a general legal
framework for the collection of Notifiable Disease data and facilitates
notification of the above infections by:
-
Placing
a duty upon doctors and laboratories to forward relevant data on cases
of these diseases, as designated in Section 30 of the Act, to STD
Services as a designated authority for the South Australian Health
Commission (SAHC).
-
Absolving
the reporting doctor and laboratory from any legal liability
concerning consent to release that information. Thus consent does not
arise as an issue with regard to notifications made in good faith.
It is wise to inform the patient that their case will be notified and
that they may be contacted during further investigation.
-
Preventing release by the SAHC
(or designated authorities) of identifying data. Notification data
containing personal details can only be secured by
court order.
The
format of reports, quantity and nature of data required are determined by
the appropriate
SAHC collection authority. Further information about
disease notification in South Australia can be found on the South
Australian Department
of Health website.
The system has two components:
-
Laboratory: copies of all positive test results are sent to STD
Services. Laboratory notification ensures that medical
notifications are monitored.
-
Medical: medical officers notify all newly diagnosed cases of
infection to STD Services on the appropriate form. The
surveillance unit sends notification forms and reply paid envelopes to
the medical officer for each new case of gonorrhoea, genital chlamydia,
syphilis, HIV infection, hepatitis B infection, hepatitis C infection and donovanosis.
Data Collection
Basic demographic data, date of test and where
appropriate, testing history, some clinical information and transmission risk factor
data are routinely collected. Data are checked for accuracy and
entered on to the STD surveillance database.
In the case of the blood
borne infections, if the notifying doctor has indicated that
the patient has had previous negative test, this information is
validated by contacting the laboratory. If risk factor information is
unknown or not stated, the patient is contacted to ascertain their risk
factor.
Data are analysed using Stata
software (version 8).
Analysis is performed quarterly and yearly according to sex, age, marital
status, exposure category and racial origin. For the blood borne
infections, data are also analysed by case category.
Surveillance data are descriptive by nature and therefore caution must
be applied when interpreting the information.
Data are published on the internet and in
annual epidemiologic reports.
Summaries are distributed electronically in quarterly reports. Information is forwarded
to state and national surveillance bodies on a regular basis. Analyses are
prepared and distributed for specific purposes, as requested.
South Australian Surveillance Definitions
Genital Chlamydial Infection
-
Isolation of Chlamydia trachomatis from a clinical (genital)
specimen.
or
-
Demonstration of Chlamydia trachomatis in a clinical (genital)
specimen by nucleic acid detection methods.
or
-
Demonstration of Chlamydia trachomatis in a clinical (genital)
specimen by antigen detection methods.
or
- Demonstration of Chlamydia trachomatis in a urine specimen by PCR.
Gonococcal Infection
Syphilis
Primary syphilis
Secondary syphilis
- Typical lesions of secondary syphilis (rash, condylomata, alopecia)
and a consistent serologic pattern before and/or after treatment. A
rising RPR titre before treatment (fourfold within 6 months) and a
corresponding fall after treatment. In secondary syphilis the RPR
titre will usually be 1:8 or greater.
Early latent syphilis
An asymptomatic patient with positive RPR and TPHA and one of the
following:
-
negative serology within the previous 2 years
-
fourfold increase in RPR titre on subsequent testing
-
fourfold decline in RPR within 12 months after treatment.
Late syphilis
Late symptomatic syphilis is suggested when a positive treponemal test
(RPR may be negative) occurs in association with typical neurological or
cardiovascular signs.
Late latent syphilis
Characterised by a positive treponemal test (TPHA of FTA-ABS) and a
negative or stable low titre RPR test. This same pattern may be due to
adequately treated syphilis or a false positive treponemal test.
Hepatitis C Infection
All positive tests for HCV infection are notified to STD
Services where cases are classified as:
Incident case (infection of less than 12 months duration)
Infection likely to be greater than 12 months
- Documented positive test result more than 12 months
ago
or
- history of diagnosed clinical illness more than 12 months ago
or
- risk behaviour confined to more than 12 months ago.
Infection of uncertain duration
No evidence of a previous test, and clinical illness not diagnosed.
Note: Indeterminate Test Results
For surveillance purposes an indeterminate test result is regarded as
negative. However, some cases may represent seroconversion and retesting
is often indicated.
Hepatitis B Infection
- Demonstration of hepatitis B surface antigen in serum.
All positive tests for HBV infection are notified to STD
Services where cases are classified as:
Acute infection
and
-
diagnosed acute clinical illness - may include jaundice or bilirubin
elevated, or at least two of the following: fever, anorexia, myalgia,
abdominal pain, lethargy
or
-
HBV core IgM antibody positive.
Infection less than 12 months
- Negative serology in the preceding 12 months.
Infection likely to be greater than 12 months
Uncertain Duration
- No evidence of a previous test, and clinical illness not diagnosed.
HIV Infection
and
All positive tests for HIV infection are notified to STD
Services where cases are classified as:
Incident Case
Infection likely to be greater than 12 months
Uncertain duration
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