Parasitology specimens – general information
- Types of specimens
- Labelling and packaging
- Hazardous specimens
- Transport to the Laboratory
- Postal address
- Sample rejection criteria
- Retention of Samples
Also see the main Tests section for general information on ordering tests, and specimen collection, packaging and transport.
Types of specimens
Diagnosis of parasitic infection may be made by direct examination of a clinical specimen to identify the presence of a parasite. Indirect methods for parasite detection (such as serology) are also available for many parasitic infections.
Faeces, blood and sera constitute the majority of samples received for analysis.
Other samples include adhesive tape smears, urine, semen, skin snips, tissue biopsies, liver aspirates, CSF, vitreous humour and corneal scrapes. Additionally, organisms suspected of causing parasitic infection, such as whole worms or arthropods can be examined.
Please send separated serum rather than whole blood for routine serology requests (to prevent lysis of sample if delayed in post). Plasma may be processed in a limited number of assays if not other sample type is available (please contact the Department of Clinical Parasitology for further information).
If you are uncertain of the type(s) of specimen(s) you should submit for analysis, telephone prior to sending the sample, in order that you can discuss the appropriateness of the specimen with a senior member of staff from the Department of Clinical Parasitology.
Labelling and packaging
Label all samples clearly with hospital number, name, and date of collection.
Location, consultant code/name, doctor’s name, bleep/ extension and test(s) required in addition to the patient details above should be put on the request form.
Specimens MUST be packaged according to Packing Instructions P650 and UN3373 requirements. Refer to the most up to date information on the HSE website (http://www.hse.gov.uk).
The outside must be marked conspicuously with:
‘BIOLOGICAL SUBSTANCE, CATEGORY B’ or ‘BIOLOGICAL SUBSTANCE, CATEGORY A’ as appropriate.
It is essential that such substances are properly packed and labelled and appropriate instruction and protection is provided to the carrier(s).
The sender is responsible for ensuring the health and safety of any employee or taxi driver that is used to transport samples to the Parasitology laboratory.
Current local and national guidelines must be followed to avoid needle stick injuries or accidental exposure to blood and blood-contaminated body fluids of those persons taking, transporting and processing the samples.
Any accident should be reported at once to your immediate superior as urgent action may be required; please refer to your local Safety Policy/Infection Control guidelines.
Ensure that the sample is correctly packed and that neither the request form nor the outside of the container should be contaminated with the sample (see below).
Ensure that the container is correctly sealed. All specimens from human sources must be regarded as potentially infectious.
High risk samples should be appropriately labelled (see below).
Any specimens from known or suspected cases of hepatitis, tuberculosis, Viral Hemorraghic Fever (VHF – see below) or HIV must be clearly identified as a ‘RISK OF INFECTION’. Refer to the most up to date information on the HSE website for guidance (http://www.hse.gov.uk) for list of ACDP categorised pathogens.
Spillage of body fluids/leaking containers may necessitate the rejection of the specimen. If this occurs, a member of the Department of Clinical Parasitology staff will inform a responsible person in the submitting organisation by telephone and advise that a request for a repeat sample be made.
The sample will be booked, cancelled and then reported to provide evidence of this activity.
Transport to the Laboratory
Specimens are received (by a number of routes, including: Royal Mail post, DX, hospital van, taxi, or by courier) at the Mortimer Market laboratory. A regular van delivery and pickup of specimens between local centres is maintained by the TDL and UCLH Transport departments.
If specimens are to be brought to the Mortimer Market laboratory personally by medical or nursing staff, they must be carried in an approved container for transport.
The Department of Clinical Parasitology is unable to receive samples sent by members of the public that are not accompanied by a request form from an approved laboratory, medical practitioner or health care provider.
See also Request Procedures.
Send your specimens, together with an official request form or signed letter containing as much clinical information as is deemed necessary and requesting the service(s) required to:
The Department of Clinical Parasitology
The Hospital for Tropical Diseases
3rd Floor Mortimer Market Centre Mortimer Market
London WC1E 6JB
Dx Number: DX 6640701
Exchange: TOTTENHAM CT RD 91 WC
We would ask that your request form has an address, a contact phone number, sample time and date added to the patient identifiable information and travel history.
Bespoke request forms can be obtained from firstname.lastname@example.org, these will ensure the correct booking of your request and resulting in a timely manner. See below
Please note: specimens sent for diagnosis or further investigation to a clinical laboratory must comply with the conditions set down in the Post Office Regulations governing the transport of pathological specimens. For insurance purposes, the value of a routine specimen is not likely to exceed £1 sterling.
Specimens which are known or suspected to contain Hazard Group 4 pathogens should not be sent by post (see www.hse.gov.uk/pubns/misc208.pdf for a list of group 4 pathogens).
Sample rejection criteria
Sample rejection criteria would include the following (although testing of specific samples may be done upon consultation with the Clinical Lead):
- Wrong sample type
- Plasma instead of serum or EDTA blood for most serology tests (unless discussed beforehand with the Parasitology Clinical Lead).
- Blood samples other than Citrate blood for Microfilarial microscopy
- Blood samples other than EDTA blood for malaria microscopy and PCR
- Peripheral blood for Leishmania microscopy and PCR (except where specifically
agreed with the Clinical Lead)
- Sample incorrectly stored/treated
- Refrigerated stool sample for stool culture
- Fixed sample for Leishmania culture (PCR will be performed)
- Fixed sample for stool PCR (Microscopy will be performed)
- Contaminated or broken container/slide
- Container contaminated due to leaking sample.
- Container/slide poses safety risk due to breakage.
- Insufficient sample volume (especially for Stronygloides Culture which requires around 20ml of stool)
- Heavily lipemic or hemolyzed serum sample.
- Sample delivery delayed beyond viable processing time.
- 15 minutes for Hot Stool sample
- 24 hours for Trypanosomal blood microscopy
- Sample unaccompanied by request form or accompanied by an incorrect or incorrectly filled out request form. Such errors would include lack of specific tests requested. Please ensure that suitable travel history is completed as specified by individual tests (such as African and South American Trypanosomiasis).
Retention of Samples
Please note that we do not keep all samples once tested, so if extra tests are required please phone the laboratory at the earliest opportunity to request the additions. Please see below for approximate sample retention times:
Standard retention times for samples
Serum and CSF supernatant for serology tests: 2 months unless specifically requested to be saved (or found to be positive), although CSFs are normally kept as long as space allows.
Citrated blood for filarial microscopy: Discarded after filtration.
EDTA Blood for microscopy: 7 days.
Body fluids inc semen, Aspirates, Duodenal and jejunal aspirates, Cyst fluids, Stool: Excess sample stored 14 days after final report produced by Parasitology Laboratory.
Bronchoalveolar Lavage, Sputum, Urine, Perianal swab: Processed sample stored 14 days after final report produced by Parasitology Laboratory (although sample may be altered by processing).
Skin scrapes, Skin snips, Swabs, Rectal scrapes, Rectal snips, Sellotape slide: Discarded after processing and testing.
Biopsies, Bone marrow, Slit skin smears: 6 months (unless all sample used in testing).
Ectoparasites, Adult worms: 1 year.
Tapeworm Segments: 48 hours after final report produced by Parasitology Laboratory.
Send away sample (including Ticks): Not kept (sent to ref lab for further ID).
Transplant Donor Samples: If clearly labelled, these are stored for 10 years.
Pre-transplant Recipient Samples:If clearly labelled, these are stored for 30 years.