diagnosis

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Since malaria is a medical emergency and clinical features of malaria are often non-specific, evaluation of a patient with a suspicion of malaria should begin immediately (1).

  • the WHO recommendations for clinical diagnosis/suspicion of uncomplicated malaria in different epidemiological settings are as follows:
    • in settings where the risk of malaria is low, clinical diagnosis of uncomplicated malaria  should be based on the possibility of exposure to malaria and a history of fever in the  previous three days with no features of other severe diseases;
    • in settings where the risk of malaria is high, clinical diagnosis should be based on a  history of fever in the previous 24 h and/or the presence of anaemia, for which pallor of the palms appears to be the most reliable sign in young children
  • in UK, one should have a high index of suspicion in every ill patient who has returned from the tropics in the previous year, especially in the previous three months (3).
    • fever on return from the tropics should be considered to be malaria until proven otherwise (3)

Physical examination findings in uncomplicated malaria are non specific.

  • fever which is the most common finding is not always seen in patients and does not have a specific pattern in majority of the patients
  • hepatomegaly, splenomegaly and somnolence are more likely to be seen in children than in adults
  • jaundice, confusion or seizure is seen in patients with severe malaria (1)

A diagnosis is achieved by repeated microscopy of thick and thin films.

  • repeat blood film examination should be done after12-24 hours and again after a further 24hours in patients with initial negative blood film
  • in partially treated patients, if blood smears are negative then examine bone marrow smears
  • in patients with 3 negative slides over a period of 48-72 h, the disease is unlikely
  • although the parasites are found in the placenta, thick films can be negative in pregnancy (1)

Rapid diagnostic test (RDTs) is another frequently used diagnostic test.

  • detects malaria antigen or enzymes
  • slightly less sensitive when compared to good quality blood films
  • useful for non experts to detect falciparum infections (not reliable to detect non falciparum malaria)
  • should not be used as a alternate for blood films

Other investigations include:

  • FBC (anaemia, raised WCC
  • platelets (often thrombocytopaenia) - highly indicative of both falciparum and non falciparum malaria in non immune adults and children (1)
  • glucose, U+Es, liver function tests
  • urinanalysis
  • blood culture
  • chest x-ray

Reference:

Last edited 12/2019 and last reviewed 04/2020