Diagnosis and Treatment of Malaria
The initial diagnostic test for suspected malaria is a peripheral blood smear with thick and thin films using Giemsa stain, and the recommended treatment depends on the Plasmodium species identified and severity of infection, with artemisinin-based combination therapy (ACT) being the first-line treatment for uncomplicated Plasmodium falciparum malaria. 1, 2
Diagnostic Approach
Initial Diagnosis
- Thick and thin blood smears with Giemsa stain should be the basis for diagnosis of malaria, as this allows for species identification and quantification of parasitemia 1
- Any febrile traveler returning from an endemic area should undergo laboratory testing for malaria, as delayed diagnosis is associated with increased mortality 1
- Clinical symptoms (fever, chills, sweats, headache) and signs (measured fever) are suggestive but not specific for malaria infection 1
Diagnostic Accuracy
- The presence of malaria parasites in peripheral blood defines malaria infection, while malaria illness is defined as the presence of symptoms in conjunction with confirmed infection 1
- When patient load exceeds laboratory capacity, a system of microscopic diagnosis for a percentage of suspected cases should be established with quality control measures 1
- Rapid diagnostic tests (RDTs) can be used as an adjunctive diagnostic modality alongside blood smears, improving diagnostic sensitivity 3, 4
Follow-up Testing
- In cases where initial testing is negative but clinical suspicion remains high, serial testing may be necessary, particularly for patients who have recently received antimalarial therapy 3
- For patients with severe P. falciparum infection, parasitemia should be monitored every 12 hours until decline (<1%) is detected, then every 24 hours until negative 1, 2
Treatment Recommendations
Uncomplicated P. falciparum Malaria
- Oral artemisinin-based combination therapy (ACT) is the first-line treatment for uncomplicated P. falciparum malaria 1
- Clinical improvement and parasite clearance should be monitored throughout treatment 1
- In areas without chloroquine resistance, chloroquine can be used at a total dose of 1,500 mg (approximately 25 mg/kg body weight) given over a 3-day period 1
Uncomplicated P. vivax Malaria
- Either chloroquine or oral ACT can be used for the treatment of uncomplicated P. vivax malaria 1
- An 8-aminoquinoline drug (primaquine or tafenoquine) should be added to eliminate liver hypnozoites and prevent relapse 1
- Before administering primaquine, patients should be tested for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency to avoid potentially life-threatening hemolysis 1
Severe Malaria
- Severe malaria (typically caused by P. falciparum) requires immediate treatment with intravenous artesunate 1, 4
- Criteria for severe malaria include impaired consciousness, high parasitemia (>2%), metabolic acidosis, hypoglycemia, renal impairment, and severe anemia 1
- After three doses of IV artesunate and when parasite levels are <1%, patients can be switched to oral ACT therapy 1
- Full blood count, hepatic, kidney, and metabolic parameters should be monitored daily during treatment of severe malaria 1
- Delayed hemolysis is a potential complication of artesunate therapy and should be monitored on days 7,14,21, and 28 after treatment 1
Special Considerations
Pregnant Women
- Pregnant women with malaria should be treated aggressively using adult regimens 1
- Chloroquine is safe during pregnancy, as is quinine (though pregnant women receiving IV quinine should be monitored carefully for hypoglycemia) 1
Monitoring Response to Treatment
- When laboratory analysis is performed, the first dose of antimalarial medication should be administered when the blood smear is taken 1
- Patients who remain symptomatic longer than 3 days into therapy should have a repeat thick smear examination 1
- The presence of Plasmodium on blood smears does not definitively prove that malaria is the cause of febrile illness; other causes should be considered and ruled out 1