Prions – morphing agents of disease
Box 2 | The Australian Quarantine Inspection Service and the need for quarantine
Australia is the most isolated of all the populated continents. This isolation has meant that Australia is free of many of the undesirable pests and diseases that occur in other areas of the world. The job of the Australian Quarantine and Inspection Service (AQIS) is to prevent the entry of these pests and diseases.
The word 'quarantine' comes from the Italian word quaranta, meaning forty. This refers to the fact that a detention period of 40 days was imposed on ships arriving from areas where cholera, yellow fever or bubonic plague occurred. Modern quarantine still operates on similar principles by holding imported animals and plants for observation, during which time any diseases carried by them should become apparent. In addition AQIS identifies those substances or organisms that, if imported, would be likely to cause an outbreak of disease, and it polices bans on their importation.
Most people have heard of rabies and foot-and-mouth disease, and are aware that these animal diseases should be kept out of Australia. But there are also many devastating plant diseases and pests that also need to be kept out. The plant quarantine section of AQIS identifies the viral, bacterial and fungal diseases likely to threaten Australian agriculture. AQIS also attempts to prevent the entry of plant parasitic insects and nematodes, many of which spread plant diseases. Of equal importance is the exclusion of foreign plant species that may enter as seeds or weeds in the soil around imported plants. The devastating effects of exotic plants such as prickly pear, lantana or privet on agricultural land and native bushland are well known.
The inspectors and research scientists working in quarantine have the unenviable task of balancing the often competing interests of tourism, agriculture, politics and business to provide an efficient service without compromising the safety of the environment and agriculture. The enormous increase in the number of international air travellers over the past 30 years has brought with it the problem of inspecting baggage, aeroplanes and containers for quarantinable items.
Agriculture demands access to new breeds or varieties of animals and plants developed overseas, and these must be introduced into Australia without introducing associated pests and diseases. The amount of time that the introduced organisms spend in quarantine must be minimised to reduce the temptation to import them illegally.
The World Trade Organisation aims to prevent countries using quarantine conditions as a barrier to trade. Quarantine bans or limitations must therefore be made on sound scientific grounds to be justifiable to our trading partners.
Finally, quarantine officers must keep up with new discoveries and technological advances and be aware of exotic organisms that may devastate our native flora.
Boxes
Box 1. Public health issues
Box 3. Australian researchers looking at prion proteins and CJD
Related sites
Bovine Spongiform Encephalopathy (Australian Quarantine Inspection Service)
Bovine Spongiform Encephalopathy (Food Standards Australia New Zealand)
Page updated november 2011.