How are biological agents classified?

In Australia and New Zealand, biological agents (infectious microorganisms) are classified into four groups according to the degree of risk to humans, animals, plants and the environment. The classification system is based on World Health Organisation guidelines and takes into account the pathogenicity of the agent; the mode and ease of transmission; host range of the agent; and the availability of effective preventive measures and treatment.

• Risk Group 1 (RG1) agents have the lowest individual and community risk and include agents that rarely cause infection in healthy hosts. Some examples of RG1 agents: laboratory strains of non-pathogenic E. coli, S. cerevisiae, soil micro-organisms.
• Risk Group 2 (RG2) agents may cause disease in a healthy host but are difficult to transmit, don’t usually cause serious or life-threatening illness and are readily treated or prevented. Examples: pathogenic E. coli, Campylobacter spp, Plasmodium spp, prions, HIV (infected blood only).
• Risk Group 3 (RG3) agents are those that usually cause serious disease and may present a serious risk to laboratory workers.  A Risk Group 3 agent may also present significant community risk if spread in the environment, but there are usually effective measures for treatment and/or prevention. Some examples: B. anthracis, hantavirus, yellow fever, HIV (cultures).
• Risk Group 4 (RG4) agents are those that present significant individual and community risks and usually produce life-threatening disease, are readily transmissible and effective prevention and/or treatment is not usually available. Examples: Ebola, Hendra and Nipah viruses.

To determine the risk group classification for a biological agent or material, refer to the AS/NZ Standard 2243.3 for indicative lists of agents and biological material.  Other resources are available here.

In Australia, biological agents are also categorised by the federal government as being 'dual-use' in the Defence and Strategic Goods List (DSGL) and as 'security sensitive' in the Security Sensitive Biological Agent (SSBA) List.