Working with human and animal derived samples

This page provides guidance on working with human and animal biological samples at UCL.

On this page

• Considerations before starting work
• Working with blood samples
• Working with unscreened samples
• Samples with known or suspected hazard group 2 pathogens
• Samples with SARS-CoV-2
• Samples that should not be handled at CL2
• Samples that can be handled at CL3
• Containment level 2 controls
• Microbiological Safety Cabinets (MSC)
• Management of sharps
• Dedicated areas
• Waste
• Personal Protective Equipment (PPE)
• Vaccination
• Accidental exposure

Considerations before starting work

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Human and animal cells on their own are not infectious, however they can create an environment for adventitious agents to exist. People who work with human or animal biological samples are at risk of potential exposure to Zoonoses and human pathogens. The type of pathogens that could potentially be present is determined by the source and type of sample being handled. For example, there is a risk of potential exposure to blood-borne pathogens when working with blood and there is a risk of potential exposure to respiratory pathogens when working with lung tissues or bronchial lavages.

Pre-screening of samples with laboratory testing can confirm the presence or absence of specified pathogens, which can allow for the elimination of samples with high-hazard pathogens. It is unlikely to test human or animal samples for all human pathogens. So it is good practice to treat all human and animal biological samples as potentially infectious, unless they have been inactivated, or are considered a well-established cell line that has been extensively characterised. 

All work with human and animal biological samples should have an authorised risk assessment in place before work starts. riskNET has specialist risk assessment templates for biological work but these do not cover human and biological samples. Risk assessments for human and animal-derived samples should identify the hazards, including the most likely pathogens potentially present, the likelihood and severity of exposure, and confirm the containment level and controls to be implemented to work safely.

Source of material	Do you know the characteristics of the source of the population which may impact the risk level, for example, the prevalence of infection or if immunocompromised? Can you use pre-screened material to reduce the risk? E.g. laboratory testing for HTLV, TB, HIV, Hepatitis B, C and E. Have samples been taken during a particular stage of infection, for example when viral titres could be high?
Risk of inadvertent cultivation	Are you working with material that supports the cultivation of bloodborne pathogens, if so, will culture length allow replication to significant levels? Is there a risk of propagation, isolation or concentration of a Hazard Group 3 microorganism?
Nature of activity	Will the work increase the likelihood of exposure e.g. through the use of sharps or by the generation of splashes or aerosols?

Working with blood samples

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• Samples of human or animal blood, including those from known HIV and Hepatitis B and or C positive sources, may be handled at Containment Level 2 (CL2) with additional controls providing there is no propagation, isolation and concentration of these blood-borne viruses. The additional procedural controls aim to prevent skin penetration through using sharps, contamination of mucous membranes and contaminated work surfaces.
• Sharps should be avoided as they increase the risk of exposure through cuts and puncture wounds. 
• Consider vaccination.
• The NHS typically screens blood samples for Syphyllis, HTLV and Hepatitis B, C and E. Blood is not typically screened for SARS-CoV-2.

Working with unscreened samples

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• Unscreened human and animal samples may potentially contain pathogens. Most material can be handled at Containment Level 2 and this should be based on a risk assessment which considers the source of the material, likely pathogens and the intended activities, to determine the controls that need to be in place.
• Any aerosol generating activities should be moved to a Microbiological Safety Cabinet (MSC).

Samples with known or suspected hazard group 2 pathogens

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• Samples known or suspected to contain Hazard Group 2 pathogens only e.g. Herpes simplex, should be handled in Containment Level 2 in all cases using Containment Level 2 practices. The potential for infection must still be considered and containment equipment like safety cabinets used as required. This should be determined by risk assessment considering the routes of transmission.
• The following PPE should be worn: lab coats, safety glasses and gloves when handling human or animal biological samples.

Samples with SARS-CoV-2

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SARS-CoV-2 samples that are permitted to be handled at CL2

• Routine laboratory blood tests carried out on auto analysers using standard CL2 practices. 
• Any aerosol generating activities should consider the use of a Microbiological Safety Cabinet (MSC).
• Diagnostic assays using whole blood, serum and plasma for routine biochemistry and haematology.
• Assays using samples where the SARS-CoV-2 virus has been inactivated using a validated method.
• Examination of bacterial or fungal cultures. 
• Staining and microscopy of heat fixed or chemically fixed smears.
• Centrifugation of routine blood samples using sealed centrifuge rotors or buckets which are loaded and unloaded in an MSC. SARS CoV-2 samples that can be handled in an MSC at CL2.

SARS-CoV-2 samples that must be carried out in an MSC at CL2

To be able to work with SARS-CoV-2 at CL2 the work should be carried out by fully trained and competent staff. There should be validated inactivation methods in place before samples can be removed from the MSC. There should be waste routes appropriate for HG3 samples. 

• Preparation of samples for molecular testing prior to sample inactivation.
• Aliquoting or diluting of respiratory tract samples, faecal samples, urine samples and tissue samples where the virus has not been inactivated.
• Inoculation of bacterial and fungal media from high-risk people.
• Urine antigen testing.
• Rapid antigen tests of respiratory tract specimens.
• Processing of any non-inactivated samples that might result in the generation of aerosols.
• Preparation and fixing (chemically or by heat) of smears for microscopy.
• Haematology or immunology work.
• Rapid diagnostics tests for malaria parasites.

Samples that should not be handled at CL2

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• Samples where there is a risk of propagation, isolation or concentration of a Hazard Group 3 pathogen where CL3 measures are required including negative air pressure.

Samples that can be handled at CL3

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• Any propagation, concentration or isolation of a Hazard Group 3 pathogen. 
• Research on Hazard Group 3 (HG3) microorganisms e.g. HIV, Hepatitis B, SARS-CoV-2 and other hazard group organisms. 

Containment level 2 controls

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• Access to a Containment Level 2 laboratory should be restricted to authorised users only.
• There should be no eating, drinking or applying of cosmetics.
• Using basic hygiene practices such as hand washing before leaving the laboratory.
• Avoiding touching the face, nose, mouth and eyes.
• Surfaces should be easy to wipe clean with disinfectant and not able to absorb contamination.
• Any aerosol generating activities should be carried out in containment devices such as a Microbiological Safety Cabinet (MSC) or centrifuges with rotors, buckets and cups with sealable lids.
• Clear segregation of different types of waste e.g. offensive waste, clinical waste, sharps waste.
• Having dedicated areas to work with human and animal samples that are free from clutter and contamination.

Microbiological Safety Cabinets (MSC)

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• When handling unscreened human and animal samples an MSC should be used when there is a risk of creating a potential infectious aerosol or infectious droplets e.g. vigorous mixing, shaking and tissue homogenisation. The MSC contains aerosols within the MSC and protects the user. 
• There is no substantive evidence that Hepatitis B and HIV can be transmitted through aerosol. However, where handling or processing may generate large droplets or splashes, containment should be used.
• The exception to the above is respiratory material such as sputum, and lung tissue. These must always be handled in an MSC because of the potential risk of Mycobacterium tuberculosis and SARS-CoV-2 infection, even when there is no reason to believe the pathogen is present.

Management of sharps

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• The term 'sharp' commonly refers to an item that can damage the skin through cuts or puncture wounds which potentially allows pathogens to enter the body to cause infection and disease. Sharps are not limited to needles and blades and can include surgical scissors, pointed-end forceps, broken glass, slides, cover slips and ampoules. This is not an exhaustive list, and all items should be assessed for sharp edges.  
• The use of glassware and sharps can increase the risk of exposure and should be prohibited. If this is not possible then safer alternatives should be considered.
• Glass items should be replaced by plastic alternatives e.g. glass pipettes substituted by plastic pipettes.
• Needles must never be resheathed.
• Sharps bins should be used to dispose of needles and blades where they are used, and must not be over-filled. 
• Sharps should not be left lying around on the bench.

Dedicated areas

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• Systems of Work should be in place to ensure that the person carrying out the work is free from the risk of disturbance from other lab users. 
• Open plan and multi-user labs where there is work with human and animal derived biological samples should be provided with a designated area or a side room to avoid disturbance. This can be achieved by carrying out the work at quieter times.
• The work area should be free from clutter and excess equipment that is not required.
• Disinfectant procedures should be in place for cleaning contaminated surfaces and spills. The disinfectants should be active against pathogens that could potentially be present in the human or animal sample. 

Waste

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• There should be clear segregation for different types of waste e.g offensive and clinical waste.
• All departments should have a hazardous waste management plan 

Personal Protective Equipment (PPE)

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• Lab coats should be worn to prevent soiling your own clothes and to prevent them from acting as a vehicle of infection. Do not enter the lab without wearing a properly fastened lab coat.
• Lab coats should be changed regularly. The frequency should be documented in a risk assessment. 
• Cuts and broken skin must be covered with waterproof dressings.
• Disposable nitrile gloves should be worn at all times when handling human material in the laboratory. This is particularly important when handling high risk samples. 
• If gloves become punctured or contaminated they should be removed immediately and disposed of. Hands should be washed and dried before getting a new pair of gloves. 
• Gloves should be removed before touching surfaces touched by others with bare hands e.g. door handles and phones.
• When you finish handling samples, gloves should be removed, discarded, and hands washed.
• Wear eye protection to prevent splashing biological material into the eyes.
• Further information on PPE can be found in the standard for personal protetive equipment within wet laboratories. 

Vaccination

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• Where vaccination is available and effective it should be offered as an additional measure. However vaccination should not be used as a primary control measure because it has variable protection. A combination of controls is more reliable for preventing exposure.
• Prior to working with blood, blood components, or unfixed tissue your line manager should arrange a referral to Workplace Health for vaccination against Hepatitis B or to confirm immunity.

Accidental exposure

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• If you think you may have been exposed to a pathogen that could potentially be in the human and animal biological samples you need to complete a referral to Medical (including mental health) emergencies at work.
• You must also notify your manager and ensure that a potential exposure is reported in riskNET as a "work related injury" so an investigation can be carried out. You may be advised to take PEP to prevent HIV infection.