Risk groups associated with safety measures in medical laboratory

• Experience has confirmed that some organisms are more hazardous to handle.
• They are more likely to infect laboratory workers than others.
• World Health Organization (WHO) has classified the microorganisms (i.e., those associated with safety measures in medical laboratory) into four risk groups.
• The list of organisms in each group may not be same for every country.
• The risk groups are described here under:

A)Risk group 1

• The organisms in this group present a low risk to the individual laboratory workers and to members of the community.
• They are unlikely to cause human diseases.
• Food spoilage bacteria, common molds and yeasts are included in this group.

  Image source: microbeonline

B)Risk group 2

• These organisms offer moderate risk to the laboratory workers and to the members of the community.
• They can cause serious human disease but are not a serious hazard.
• Immunization and treatment are available and the risk of spread in the community is not great.
• The organisms like Staphylococci, Streptococci, Enterobacteria (except Salmonella Typhi), Clostridia, Vibrio, Adenovirus, Poliovirus, Hepatitis virus, Toxoplasma and Leishmania, etc. are examples of this risk group.

                                                                             Image source: biosafetycabinet

C)Risk group 3

• This group contains organisms that present a high risk to the laboratory workers but a low risk to the community.
• They do not ordinarily spread from one individual to another.
• There are effective vaccines and chemotherapeutic materials.
• Organisms like Brucella, Tubercle bacilli, Salmonella typhi, Francisella, plaque organisms, many arboviruses, LCM viruses, Rickettsiae, Chlamydiae, Coccidioides, Histoplasma, HIV, etc. are included in this group.

D)Risk group 4

• The agents in this group are all viruses.
• They offer a high risk to the laboratory workers and to the community.
• They can cause serious diseases and are readily transmitted from one individual to another.
• At present there are no vaccines or chemotherapeutic agents against these viruses.
• Small pox, viruses of certain hemorrhagic fevers including Marburg, Lassa and Ebola equine and other encephalitis viruses are included in this group.

References: 

i) https://ehs.umass.edu/sites/default/files/BiosafetyTrainingHandout2018_0.pdf

ii) https://www.labmanager.com/lab-health-and-safety/laboratory-hazards-and-risks-18238

iii) https://ehs.virginia.edu/Biosafety-Riskgroups.html

iv) https://microbeonline.com/primary-bio-safety-levels-and-agents-of-disease/

Risk groups associated with safety measures in medical laboratory