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Malaria Screen

Department of Haematology

*** CONSIDER VIRAL HAEMORRHAGIC FEVER ***

Always consider Viral Haemorrhagic Fever (eg. Ebola) as part of the differential diagnosis in patients with unexplained fever following return from an area of risk. All patients must be risk assessed for VHF before any Pathological specimens are taken.

When requesting Malaria screening, ensure the country of travel and the outcome of the VHF assessment (unlikely, low possibility or high possibility) is recorded on the request form. The laboratory will not process the sample without this information.

For further information please see the GHNHSFT Viral Haemorrhagic Fever Policy and associated action cards.

Notes

  • The following tests will be performed:
    • Thick and thin blood film examination.
    • Antigen test (performed once per episode).
    • A parasite count on all findings of Plasmodium falciparum and Plasmodium knowlesi. Quantification of parasites should be repeated daily until no parasites (other than gametocytes) remain. (Reference - BSH guidelines for the Laboratory Diagnosis of Malaria. British Journal of Haematology Wiley Online Library)
    • Tested alongside a FBC.
  • All positive results are referred to The London School of Tropical Medicine for confirmation.
  • Clinical advice regarding the management of a patient with a positive malaria screen is available via the Consultant Microbiologist.
  • A negative result does not exclude a diagnosis of Malaria. Repeat tests should be requested if clinically indicated.
  • Test performed at CGH and GRH.

Information Required

Please ensure all request forms include the following information:

  • Countries visited and duration of stay
  • VHF Assessment
  • Anti-malarial prophylaxis taken, if any
  • Onset of illness
  • Clinical details

Sample Requirements

2ml or 4ml EDTA sample.

EDTA with cap

Important Note

The sample should ideally be less than 4 hours old upon receipt, as parasite morphology changes over time. Every attempt should be made to ensure the samples reach the laboratory before 4pm.

Turnaround Time

All requests for malarial parasites are treated as urgent requests.

  • Antigen test: 2 hours
  • Blood film examination: 2 hours (if the antigen test is positive)

Sample Storage and Retention

  • Pre analysis storage: do not store, send to laboratory immediately.
  • Sample retention by lab: EDTA samples are retained for a minimum of 48 hours at 2-10°C. Blood films are retained for a minimum of 7 days at ambient (15-30°C) temperature.

This test can be added on to a previous request as long as there is sufficient sample remaining and the sample is less than 4 hours old.

Reference Range

Neg/Pos

All positive results are phoned to the requestor

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