Overview of diagnostic testing

Last update: 14 March 2017

Early and accurate diagnosis of malaria is essential for both effective disease management and malaria surveillance. High-quality malaria diagnosis is important in all settings as misdiagnosis can result in significant morbidity and mortality.

Parasitological confirmation of diagnosis

WHO recommends prompt parasitological confirmation of diagnosis either by microscopy or malaria rapid diagnostic test (RDT) in all patients with suspected malaria before treatment is administered. The choice of method depends on local circumstances, including patient case-load, epidemiology of malaria, and availability of skilled laboratory technicians.

Parasite-based diagnostic testing of malaria improves the overall management of patients with febrile illnesses, particularly by helping to identify patients who do not have malaria and consequently do not need an antimalarial medicine but a different treatment. It may also help reduce the emergence and spread of drug resistance by reserving antimalarials for those who actually have malaria.

The benefit of parasitologically confirmed diagnosis is dependent on health-care providers adhering to the test results in managing the patient. Where quality-assured parasitological diagnosis is promptly available, antimalarial treatment should be limited to test-positive cases while negative cases should be assessed for other causes of fever.

Microscopy and RDTs are the primary choices for diagnosing malaria in the field. With regard to the molecular detection of malaria, WHO recommends that nucleic acid amplification tests, which can detect low density malaria infections, be considered only for epidemiological research and surveys mapping sub-microscopic infections.

Parasite-based diagnosis for all age groups

The number of countries that have adopted and implemented policies for the parasite-based diagnosis of malaria is increasing. Ninety-five countries and territories have adopted a policy to test all patients with suspected malaria before treating with antimalarial medicines. Diagnostic testing is free of charge in the public sector in 86 countries.

The proportion of patients suspected of having malaria who receive a malaria diagnostic test has increased substantially since 2010, when WHO recommended testing of all suspected malaria cases. In 2015, 74% of patients with suspected malaria in public health facilities in the WHO African Region received a diagnostic test, compared to 41% in 2010.

The volume of RDT sales to the public and private sectors of endemic countries increased from 88 million in 2010 to 320 million in 2014, but subsequently fell to 270 million in 2015. The number of patients tested by microscopic examination increased to 203 million in 2014, of which more than 120 million were performed in India.

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