Mpox (monkeypox): diagnostic testing

Information on taking, submitting and processing samples which potentially contain mpox virus.

Applies to England

This guidance is aimed at healthcare workers and clinical diagnostic laboratories both in the public and private sectors. It is to be used for all suspected cases, irrespective of whether the case is being managed as a high consequence infectious disease (HCID) case or not; however, cases meeting the operational definition for suspected HCID should be discussed with the Imported Fever Service prior to testing.

Mpox diagnostic testing is available in UKHSA laboratories and some NHS laboratories. Where these services are available these should be accessed according to local guidance; otherwise mpox diagnostic testing service can be accessed through this guidance.

Information is available on the mpox case definitions, and will continue to be updated. There is also information available on the classification of contacts of mpox cases and follow-up advice for vaccination and follow-up.

Infections such as chickenpox, herpes simplex virus (HSV), molluscum contagiosum and syphilis are all still circulating. Diagnostic testing for these infections should be undertaken as usual, with testing for mpox proceeding in parallel if deemed necessary.

Suspected cases

In the first instance, suspected cases must be discussed with local infection clinicians (infectious diseases, microbiology, virology or genitourinary medicine as appropriate). Make sure that the request form indicates the risk factors and the reason that mpox is suspected.

Personal protective equipment (PPE)

The minimum recommended PPE for healthcare workers who need to be within 1 metre of a suspected case of mpox is droplet and contact precautions, with eye protection where there is a possibility of splash (for example taking diagnostic samplestests such as throat swab or deroofing lesions) as outlined in the NHS England (NHSE) national infection prevention and control manual.

The national infection prevention and control manual also outlines the minimum recommended level of PPE for inpatient care.

Sampling for diagnostic testing

Mpox is diagnosed by PCR test for the monkeypox virus (MPXV) on a viral swab taken from one or more vesicles or ulcers. Swabs should be sent in viral transport media.

Follow the instructions below:

1. Ensure that you are wearing the minimum appropriate PPE as above.

2. Take a viral swab in viral culture medium or viral transport medium (for example Virocult®) from an open sore or from the surface of a vesicle. If other wounds are present, ensure that the sample is definitely taken from a vesicle, an ulcer or a crusted vesicle. Rub the swab over the lesion and place the swab in the collectionviral tube.culture Iftube or viral transport medium. Throat swabs are also suitable samples if there are pharyngeal lesions, atypical lesions, or if the patient is a throatcontact swabof shoulda alsoconfirmed becase taken.with a possible prodrome syndrome but without a typical rash. Label the tube with the patient’s name and date of birth, the date and site of the sample. Note that unlabelled tubes cannot be processed.

3. AFor viralhigh throatrisk swab should be taken for high-risk contacts of a confirmed or highly probable case who have developed systemic symptoms but do not have a rash or lesions thatfor cansampling, beyou sampled.should Pleasetake notea throat swab in viral transport media. Note that even if the throat swab is negative, the individual must continue with monitoring and isolation as instructed by theirby UKHSA’s local health protection team, and should be reassessed and sampled if further symptoms develop.

4. Samples for investigation of other infections, including sexually transmitted infections, should be packaged separately, with separate request forms.

5. Samples should be sent to your normal local laboratory. Testing for other infections, for example HSV, varicella-zoster virus (VZV), or syphilis, should follow normal local procedures. If MPXVmpox testing is not provided locally, the laboratory should also forward the samples to the Rare and Imported Pathogens Laboratory (RIPL) for MPXVmpox PCR.

Sampling for monitoring confirmed or highly probable cases

If follow-up testing is required from a confirmed or highly probable case, either because of clinical deterioration or to inform discharge from isolation to an inpatient setting, additional samples should be taken and should include the following:

  • a lesion swab and throat swab in viral transport medium
  • a blood sample in an EDTA tube
  • a urine sample in a universal sterile container

Samples shouldfrom beconfirmed sentor tohighly aprobable laboratorycases capable of processingmpox theseshould samplesbe forsent RIPL as below.

Submitting diagnostic samples to RIPL for testing

1. Download and complete the MPXVmpox testing request form. If you require urgent reporting of results (usually only for suspected HCID cases), please ensure that you provide a direct contact number for the physician designated to receive results, which may be out of hours.

2. Package the samples carefully following the guidance on page 17 of the RIPL user manual. You must ensure that stoppers and lids are firmly attached, the tubes are labelled with the sample type (for example swab left palm, penile lesion), patient name and date of birth. Do not use an internal study number. Samples that have leaked in transit cannot be processed.

3. Send the samples to your normal local laboratory. Any additional samples for sexually transmitted infections should be packaged separately.

4. Inform your local laboratory that the samples for MPXVmpox testing should be forwarded to RIPL for testing. This should be through a licensed Category B courier to:

Rare and Imported Pathogens Laboratory
Manor Farm Road
Porton Down
Salisbury SP4 0JG

DX 6930400, Salisbury 92 SP

The working hours contact for RIPL is 01980 612 348 from 9am to 5pm on weekdays. You can also email but do not include patient identifiable information.

5. If urgent testing is required, including out of hours, this must be discussed and agreed with the on-call Imported Fever Service consultant (0844 778 8990). Urgent testing will normally be reserved only for suspected HCID cases imported from West or Central Africa (see guidance on the HCID status of mpox).

Test results

All results will be sent to the referring laboratory through the standard electronic reporting system.

The RIPL office can answer enquiries about results enquiries during opening hours. If chasing the whereabouts of a sample, ensure your courier has been contacted first to ensure that receipt of the samples has occurred. If the sample has been sent correctly via a Category B courier, the courier should be able to confirm delivery time.

Information for laboratories handling samples potentially containing MPXVmpox virus

MPXVMpox is a Hazard Group (HG) 3 pathogen. Under normal circumstances, any procedure with HG3 pathogens involving potentially infectious material, where there is a risk of generating aerosols, droplets or splashes, must be performed within an MSC at CL3. However, some diagnostic samples may be handled at CL2 subject to local risk assessment. The following table provides the minimum containment level for handling samples suspected or confirmed to contain MPXV.mpox.

Specimen type/test Suspect/probable/possible case Confirmed/highly probable case
Nucleic acid extraction for the molecular detection of MPXVmpox virus MSC I, II or III at CL3 until after virus inactivation. MSC I, II or III at CL3 until after virus inactivation.
Sample transport Transported via Category B route Transported via Category B route
Nucleic acid extraction of skin lesion swabs for molecular assays of infections other than MPXVmpox virus (for example herpes simplex virus or syphilis) MSC I, II or III at CL2 until after virus inactivation MSC I, II or III at CL3 until after virus inactivation
Respiratory samples MSC I, II or III at CL2 MSC I, II or III at CL2
Other microbiological samples where manual manipulation is required for example plating of culture swabs, urine antigen testing, manipulation of blood cultures or urine MSC I, II or III at CL2 MSC I, II or III at CL3
Routine laboratory blood tests Autoanalysers at CL2 Autoanalysers at CL2
Waste disposal Standard protocols for disinfection and waste disposal Standard protocols for disinfection and waste disposal
Routine blood tests outside of an autoanalyzer Open bench at CL2 with PPE (gloves, laboratory coat +/- eye protection subject to risk assessment)

Samples must be centrifuged using sealed centrifuge rotors or sample cups which are loaded and unloaded in an MSC
Open bench at CL2 with PPE (gloves, laboratory coat +/- eye protection subject to risk assessment)

Samples must be centrifuged using sealed centrifuge rotors or sample cups which are loaded and unloaded in an MSC
Point of care / near patient testing of lesion swabs Generally, not to be performed but is possible with a local risk assessment which identifies correct PPE to protect the healthcare worker Generally, not to be performed but is possible with a local risk assessment which identifies correct PPE to protect the healthcare worker
Point of care / near patient testing of respiratory samples Should not be analysed unless a local risk assessment has been completed and shows that it can be undertaken safely. Near-patient tests for viral nucleic acid amplification vary widely in their general safety and where aerosols or droplets may be generated. If a local risk assessment can show that any aerosol or droplet generation occurs within a closed analyser, and external surfaces can be cleaned with detergent-based disinfectant, then these tests may be used Not to be performed
Point of care tests / near patient testing of other samples, for example blood gases May be used subject to local risk assessment regarding the potential for the generation of splashes and droplets, and the appropriate use of PPE and disinfection May be used subject to local risk assessment regarding the potential for the generation of splashes and droplets, and the appropriate use of PPE and disinfection

Laboratory exposure may occur via needlestick injury, direct specimen contact, or inhalation of aerosols. These exposures can be avoided if standard biosafety precautions are taken.

It is important that other diagnostic testing is not delayed while waiting for the results of MPXVmpox testing so as not to delay diagnosis of other illness that may require urgent treatment.

Other procedures, such as extraction or procedures which may generate aerosols, should be performed in a CL3 facility with staff wearing cuffed, back-fastening gowns, gloves and goggles.

For PCR testing of specimens from suspected mpox cases (for example testing for syphilis or HSV), the specimens should be opened in an appropriate microbiological safety cabinet in a CL2 facility.

Samples can be inactivated before extraction by heating for 1 hour at 60°C in a validated water-bath or block designed to ensure even heat distribution throughout standard specimen tubes.

Guanidine/guanidinium buffers such as AVL can also be used but work best with additional non-denaturing surfactants (see Inactivation of orthopoxvirus for diagnostic PCR analysis by Vinner and Fomsgaard, and PAHO/WHO guidance).

Inactivated samples can be handled safely with standard laboratory precautions.

Samples from confirmed and highly probable mpox cases should be labelled appropriately so that laboratories can ensure that they are handled correctly with the necessary additional precautions as outlined above.

For routine testing of blood samples from suspected or confirmed mpox cases (for example for biochemistry or haematology), standard clinical laboratory precautions can be followed, but aerosol generating procedures should be avoided. The risk of infection from these samples is less than that for hepatitis B or any other similar organism.

Surfaces should be decontaminated with standard disinfectants. Waste should be autoclaved and disposed of as per standard laboratory procedures.

Guidance for laboratories seeking to establish mpox diagnostic testing capability

UKHSA provides a diagnostic testing service free of charge to NHS users for public health purposes.

UKHSA does not restrict NHS or private laboratories from establishing their own MPXVmpox testing service, but any such service would be provided at their own expense.

Laboratories planning on establishing local diagnostic testing should ensure they remain compliant with relevant legislation, perform appropriate risk assessments, and assure ongoing quality. Laboratories should be aware that MPXVmpox is schedule V restricted by the Anti-terrorism, Crime and Security Act 2001.

Laboratories should also ensure that their testing provision is able to maintain compliance with the different operational definitions of HCID for mpox within their testing pathways, including the ability to distinguish or escalate for confirmation cases that may be classified as an HCID.

UKHSA does not approve, endorse or recommend a specific commercial MPXVmpox diagnostic test, although a MPXV-specificmpox-specific nucleic acid amplification test is recommended, and use of an orthopox-only test is discouraged.

The use of multi-target assays is recommended. Reports of genomic deletions in assay target regions that may result in false negatives have been reported in rare circumstances.

Please discuss the case with RIPL if you suspect you have a case with an assay target dropout (for example orthopox positive/MPXVpositive/mpox negative).

At present, only nucleic acid amplification tests (typically PCR-based) are recommended for provision of testing services. Other test types are available on the market, however their performance characteristics in this outbreak are uncertain and are not recommended by UKHSA.

A list of tests on the commercial market is maintained by FIND.

Recommended process prior to testing

To ensure confidence and compliance with the current notifiable diseases regulations,regulation laboratories, it is recommended that UK laboratories follow the process outlined below prior to commencing with a mpox testing service.

1. Submit a copy of their nucleic acid assay verification file and reporting criteria for peer review to the UKHSA mpox Diagnostics team (contact details below), along with the intended go live date and predicted capacity.

2. Technical specialists at UKHSA Porton Down will provide a peer review that assay selection is reasonable for the service offered and remove the need for confirmatory testing of positive samples by RIPL. This peer review is not an assay approval and laboratories should ensure they follow their standard local assay approval processes including through relevant accredited bodies.

3. Laboratories that have undergone satisfactory peer review are not required to submit samples to UKHSA Porton Down for confirmation.

4. Samples for sequencing will be required and UKHSA will arrange couriers for this if existing courier routes aren’t in place. As a minimum, it is recommended that positive samples from women, children, patients with overseas travel history and/or treated with anti-viral medicines (such as tecovirimat)tecoviramat) are retained for sequencing.

5. Laboratory should work with their UKHSA regional laboratory surveillance Second Generation Surveillance System (SGSS) leads to ensure data feeds from their laboratory systems are reporting correctly to SGSS data system.

6. For monitoring purposes, laboratories should provide both MPXVmpox negative and positive results into SGSS.

7. It is critical that data collection and reporting systems are in place and tested with mpox data analytics teams before the service goes live to ensure this feeds into the national surveillance programme.

8. A turnaround time within 24 hours from sample receipt, and preferably same day, is desirable.

If a laboratory intends to provide testing using an alternative testing methodology please contact the UKHSA mpox Diagnostics team (contact details below) to discuss prior to offering the service as this may have significant implications for public health monitoring purposes.

UKHSA Porton Down may be able to supply control material to assist in assay verification activities (contact through the UKHSA mpox Diagnostics team, see below). AnA MPXVmpox External Quality Assurance (EQA) exercise delivered through National External Quality Assessment Services (NEQAS) is planned so submission of assay verification data can help ensure laboratories are considered for participation in that EQA exercise when it becomes available.

UKHSA mpox Diagnostics team contact details:

Published 24 May 2022
Last updated 235 JanuaryDecember 20232022 + show all updates
  1. Updated Sampling for diagnostic testing, Sampling for monitoring cases and Submitting samples to RIPL for testing sections.

  2. Updated sections: Submitting diagnostic samples to RIPL for testing and Test results.

  3. Updated information on out of hours testing.

  4. Updated information on submitting samples. Clarified that guidance is for both HCID and non-HCID cases.

  5. Amended in line with the introduction of highly probable case definition and to include information for laboratories seeking to establish monkeypox diagnostic testing capability.

  6. Removed information about clinical helpline.

  7. Updated information on transport of samples from confirmed cases and information on when samples will be processed.

  8. Added link to monkeypox testing request form.

  9. Updated sections on sampling for diagnostic testing, submitting diagnostic samples for testing, test results and information for laboratories handling samples.

  10. Removed the request for blood and urine samples and throat swabs to be submitted for diagnostic testing.

  11. Added information about contacting the monkeypox clinical helpline.

  12. Updated guidance.

  13. First published.