Guidance

Viral haemorrhagic fever (VHF) sample testing from the imported fever service

Updated 24 November 2022

Doctors requesting advice on testing samples from possible viral haemorrhagic fever (VHF) cases should contact their local consultant in infectious diseases, microbiology or virology in the first instance.

If the case merits consideration for VHF testing, based on the discussion with the local infection consultant and assessment using the Advisory Committee on Dangerous Pathogens (ACDP) VHF risk assessment algorithm, the infection consultant should contact the imported fever service.

Please note that ‘high possibility’ on the VHF risk assessment algorithm does not necessarily mean that there is a high likelihood or probability of VHF infection.

Access to testing services

VHF testing is only available through the imported fever service (IFS). All requests for VHF testing must be discussed with the IFS before sending samples. The phone number for the IFS is 0844 778 8990. You will find more contact details at the end of this page.

VHF testing is carried out at the UK Health Security Agency’s (UKHSA) rare and imported pathogens laboratory (RIPL), known as UKHSA Porton Down.

VHF testing for patients in Scotland is performed by the Scottish National VHF Testing Service (SNVTS) based at the Royal Infirmary of Edinburgh.

The RIPL and Edinburgh laboratories will NOT accept samples for urgent VHF testing that have not been discussed with both the local infection consultant and the IFS.

Assessment by the IFS

The IFS doctor will:

• discuss the case with the referring infection consultant, decide whether testing is required, and make a risk assessment of the likelihood that the patient has a VHF infection
• determine the degree of urgency and the samples to take, and will advise on the best way to transport samples to RIPL. They will also ensure that referring laboratory staff can liaise directly with RIPL laboratory staff on packaging, specimen tracking and more
• discuss with the local infection consultant any immediate treatment to be instituted for likely differential diagnoses, isolation procedures, and other investigations that should be undertaken locally and the safety of doing them in the particular case referred
• direct the referring clinician to inform the local health protection team (HPT) of the assessed likelihood of VHF infection and the plan for testing
• arrange for sample testing at RIPL for the samples to be tested for the necessary tests. This will usually include testing for key agents that can masquerade as VHF, where appropriate

Please see the ACDP VHF guidance for supporting documents on laboratory procedures.

Taking samples

For VHF testing at RIPL, the minimum samples are:

• serum: 4.5 mL serum separation gel tube
• ethylenediamine tetraacetic acid (EDTA) blood: 4.5 mL EDTA tube

Ideally, a urine sample should also be sent, but testing should not be delayed in order to obtain a urine sample.

IFS and RIPL clinicians may also advise taking additional samples depending on exposure and presentation of the case, either in parallel with the VHF testing or dependent on the results.

For paediatric samples, the minimum sample is 1 mL of blood for VHF testing (either screw top bottles or vacutainers are acceptable). However, a full imported infections screen at RIPL may not be possible with this amount and a larger volume is still preferred if possible.

Packaging and transport

The IFS clinician will advise on whether samples are to be sent as ‘category A’ or as ‘category B’. This will depend upon the likelihood of a VHF diagnosis from exposure history and the clinical presentation of the patient.

Samples must be packaged according to the relevant international guidelines for UN2814 (category A) or UN 3373 (category B). RIPL staff will provide advice to technical staff in the referring hospital on request. In the majority of cases, the advice will be that samples may be sent as category B.

Sending laboratories must also provide the testing laboratory with:

• the name of the courier
• the tracking number and account code
• the estimated delivery time at UKHSA Porton Down
• a completed RIPL request form

Carriage costs are the responsibility of the referring hospital.

Courier options

You may choose to use a courier known to you but the following organisations are known to provide both category A and category B transport.

Courier name	Telephone
Topspeed Couriers	01565 631840 or 0800 856 2464 at any time
PDP Couriers	01784 420 466 at any time
Dangerous Goods International (DGI)	0208 814 0404

Tests, timings and results

The presentation of most imported diseases is very similar and it can be very difficult clinically to distinguish between them.

Testing includes a panel of polymerase chain reaction (PCR) assays for a number of imported infections that could be the cause of a febrile illness in a returning traveller with possible exposure to a VHF. There is no charge for the VHF PCR panel testing at RIPL.

At RIPL, VHF samples are usually tested for the haemorrhagic fevers present in the area where the patient was potentially exposed, and for other relevant causes of fever.

RIPL testing for suspected VHF may include the follow depending on exposure history:

• Ebola (pan-species assay and relevant sub-species, as appropriate)
• Marburg
• Lassa fever
• Crimean Congo Haemorrhagic Fever (CCHF)
• Dengue
• Chikungunya
• Rift Valley fever
• Rickettsia (generic; covers spotted fevers and typhus group)
• malaria
• leptospirosis

These are in-house real-time PCRs apart from malaria, which is an in-house conventional gel PCRs.

Timings

For all urgent samples, where it has been agreed to process the samples immediately on receipt, Ebola, Lassa, Marburg and CCHF results are normally available within 4 to 6 hours of arrival in the laboratories and will be telephoned.

At RIPL, the complete VHF panel results are usually available within 7 to 8 hours of arrival but any positives in the other real-time assays are usually available sooner and will be telephoned as soon as they are known.

Neither IFS nor RIPL are responsible for taking samples in the referring hospital, arranging for samples to be packed locally or arranging transport, or for any delays incurred in this process.

Results

VHF testing results are telephoned by RIPL clinicians as soon as they are available. The referring clinical team is always informed first. Please do not call the RIPL clinical staff for results out of hours, as we cannot give out results for samples that are still in transit or for tests that are incomplete.

RIPL clinicians will advise the referring clinician on the further clinical management of the case, including infection control, as appropriate.

In the event of a positive result, RIPL clinicians will inform the referring clinician of the result first. Request that the clinician informs the rest of their clinical team, laboratory, Infection Prevention and Control team and other key contacts within their trust. The referring clinician will be advised to contact their local HPT immediately and ask the duty clinician to phone the RIPL clinician.

The RIPL clinician will also notify the UKHSA Emergency Response Department (ERD). This will trigger a notification and activation cascade to include:

• NHS Emergency Preparedness, Resilience and Response (EPRR)
• the high consequence infectious diseases (HCID) network
• relevant senior UKHSA staff

Contact details

Telephone numbers

Imported fever service: 0844 778 8990

This number automatically routes to the clinician’s mobile phone. Please allow time for the connection to be made and for the doctor to answer it. The IFS doctor is unable to give any other results out through this number.

RIPL on-call clinician: 07789 031 672

This number re-routes to the on-call person’s phone so please allow time for connection.

If all else fails, contact RIPL laboratory technician: 01980 612 100

UKHSA Porton Down switchboard will ensure someone gets back to you.

Testing laboratory address

Rare and imported pathogens laboratory (RIPL)

UK Health Security Agency
Manor Farm Road
Porton Down
Wiltshire
SP4 0JG

Email [email protected]

Telephone 01980 612348 (available 9am to 5pm, Monday to Friday)

DX address DX 6930400, Salisbury 92 SP