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Assessment of Tertiary Students for active and latent tuberculosis: Helpful Hints for General Practitioners.
While tuberculosis (TB) is not common in Australia, each year 1200-1300 cases of TB are diagnosed nationally, of which almost 10%
are tertiary students and almost 5% are past or current healthcare workers (HCW). The majority of such cases, but not all, are born
overseas in countries with much higher rates of TB than we have in Australia.
Queensland Health requires all students who are to undertake placement in a clinical setting to complete a TB risk assessment
questionnaire to help identify active TB and latent TB. Those who are identified as being at risk, may present to their GP for further
assessment.
There are three main scenarios to consider.
A. Student self-reports symptoms which could be active TB
The symptoms as described on the risk assessment which may prompt a referral for assessment are one or more of the following:
1. Cough for more than 2 weeks (not related to an existing diagnosis or condition)
2. Unexplained fever for more than 1 week
3. Recent unexplained weight loss
4. Coughing up blood
5. Excessive sweating at night for more than one week.
As prolonged cough and haemoptysis may be features of pulmonary TB, it is recommended that such symptoms be identified at the
time of booking-in the patient (if possible), in order that appropriate infection control precautions may be implemented, such as the
patient waiting outside until called and the patient wearing a surgical mask when inside the practice (this reduces production of
infectious aerosols should the patient actually have TB).
You may prefer to promptly refer your patient to a public TB Control Unit (TBCU) (contact details below) where no further out of pocket
expenses will be incurred for the student. Similarly, a referral to a specialist experienced in TB medicine (usually a respiratory
physician or infectious diseases physician) may be considered.
Investigations which may be initiated from primary care, if undertaken, should include:
- Three expectorated sputum for “AFBs” (acid fast bacilli) – note sputa should be collected external to a GP practice or
pathology collection office (away from others) unless appropriate negative pressure facilities are available.
- A CXR (PA and lateral views).
If the CXR is abnormal or sputa are smear or culture positive for TB, referral to a TBCU or a specialist experienced in TB medicine is
recommended.
B. Student is asymptomatic but has risk factors that make latent TB more likely
In most cases, it is being born in a country with high TB incidence which makes TB infection more likely, but living in such countries for
a prolonged period and working in clinical or laboratory areas with increased potential exposure to TB are also risk factors.
People with latent TB are asymptomatic but they may progress to active TB including infectious pulmonary TB with a lifetime risk of
~10%. This risk can be reduced by 80 – 90% by administering antimicrobial therapy for 4 – 9 months (depending on the agent used).
Students with increased risk for latent TB are asked to present to a TBCU or GP for further testing.
Latent TB can only be diagnosed by a test which measures immune response to TB proteins; either an interferon-gamma release
assay (IGRA) or a tuberculin skin test.
The most practical test in general practice is the QuantiFERON® Gold Plus test (IGRA) as it requires a single blood sample, is done by
public and private labs and is unaffected by previous BCG vaccination.
