Malaria requires urgent diagnosis due to the potential severity of the infection and rapid progression of the disease. A rapid diagnosis is therefore a crucial part of an efficient management process.
The confirmation of suspected imported malaria is based on finding direct and/or indirect evidence of the parasite in a blood sample.
Such testing should be performed immediately, without waiting for shivering or high fever.
As soon as a positive result is obtained, appropriate treatment should be started as soon as possible. Treatment must be adapted to the patient’s degree of severity.
The positive diagnosis of malaria is confirmed by the detection of the parasite on a thin blood smear and a thick drop. These are reference techniques, but require a certain amount of expertise.
The expected elements are:
- positive diagnosis of malaria (thick drop)
- species identification (thin blood smear)
- parasitemia (parasite density expressed as number of parasitized red blood cells/µL or as a percentage) (thin blood smear)
Rapid diagnostic tests can also be used. They detect specific antigens (HRP-2, pLDH) and pathogenic species in humans. Their sensitivity can reach 100%, and is correlated with parasitaemia (false negative possible in case of very low parasitaemia) for P. falciparum.
The HRP-2 antigen test can remain positive for 2 to 6 weeks after an episode of malaria. It should not be used to diagnose a relapse after treatment. They enable rapid diagnosis and do not require any particular expertise, but cannot be used to assess parasitaemia.