Tuberculosis testing and immunisation in the Australian Defence Force
see related article "BCG vaccine in Australia"
In the course of peacetime service in Australia, the exposure of Australian Defence Force personnel to tuberculosis, and hence risk of infection, is similar to that of the general population. However, when operationally deployed, particularly in Australia's region of interest, personnel may be exposed to infected people. This risk is heightened during humanitarian or peace-keeping operations.
In the past, the mainstay of prevention was immunisation with BCG vaccine. In recent times the widespread use of BCG vaccination has been shown to prevent few cases in regions with low incidence rates. The vaccine may also cause false positives in Mantoux tests and this may increase the difficulty in diagnosing tuberculosis infection.
The Australian Defence Force has followed the guidelines of the US Centers for Disease Control and Prevention and, therefore, does not recommend routine BCG vaccination.1
Within the Australian Defence Force, screening for tuberculosis is undertaken by skin testing all personnel on entry, using 10 units of tuberculin purified protein derivative. Tuberculin skin testing may also be performed in two steps if the initial induration is less than 15 mm diameter. It is not performed by using multiple puncture tests (Heaf test).2
The tuberculin skin test is also used to screen personnel after redeployment or removal from a country with a high incidence of tuberculosis, provided that the period of redeployment has been at least three months. This testing is performed three months after the personnel return to Australia. A high incidence country is one in which the annual tuberculosis incidence is at least 49 per 100 000. For people visiting and residing in such an area for at least 3–12 months, incidence rates for tuberculosis infection have been reported as 1.8%.3
Personnel who have been exposed to high risk situations are also tested. This latter group includes those people who have spent a total of eight or more hours with an infected person in a confined environment, as well as healthcare workers who have had regular close contact with an index case.
- US Centers for Disease Control and Prevention. Core curriculum on tuberculosis: what the clinician should know. 4th ed. Atlanta, GA: Division of Tuberculosis Elimination, Centers for Disease Control and Prevention; 2000. www.cdc.gov/nchstp/tb/pubs/corecurr/77-CoreCurriculumonTB.pdf
- Director-General Defence Health Service. Prevention and management of tuberculosis. Health Bulletin 2003;2(2 April). www.defence.gov.au/dpe/dhs/infocentre/publications/bulletins /HB02_03.pdf
- Cobelens FGJ, van Deutekom H, Draayer-Jansen IWE, Schepp-Beelen ACHM, van Gerven PJHJ, van Kessel RPM, et al. Risk of infection with Mycobacterium tuberculosis in travellers to areas of high tuberculosis endemicity. Lancet 2000;356:461-5.