From: "Test and treat" or presumptive treatment for malaria in high transmission situations? A reflection on the latest WHO guidelines
Advantages of parasitological diagnosis (according to WHO guidelines, section 6.1, 6.2)
Disadvantages of parasitological diagnosis in high transmission areas
Diagnosis based on clinical features alone has very low specificity and results in over-treatment
Parasitological diagnosis has low specificity
Improved patient care in parasite-positive patients
In a patient with fever, the presence of parasites neither reliably confirms malaria as the cause of the fever, nor excludes the possibility of other diseases
Identification of parasite-negative patients in whom another diagnosis must be sought
Other diagnoses should be sought in all patients, irrespective of the presence of malaria parasites
Prevention of unnecessary use of anti-malarials, reducing frequency of adverse effects especially in those who do not need the medicines, and drug pressure selecting for resistant parasites
Clinicians often prescribe anti-malarials even for patients with a negative test. Prescribing anti-malarials to parasite-negative patients will not increase selection pressure for new drug resistant mutations.
Improved malaria case detection and reporting
Some "cases" detected in high-transmission areas are incidental carriers of malaria parasites, presenting with another disease
Confirmation of treatment failures
RDTs cannot confirm treatment failures. It is only possible to do this with microscopy.