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
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