Malaria is a major infectious disease caused by Plasmodium parasites, transmitted to humans by female Anopheles mosquitoes. Despite global control efforts, malaria remains a significant cause of morbidity and mortality, especially in resource-limited settings.

I. Epidemiology & Public Health Burden
- Global Estimate: ~241 million cases, >600,000 deaths annually (WHO 2021).
- High-Risk Regions: Sub-Saharan Africa (>90% cases), Southeast Asia, Latin America.
- At-Risk Groups: Young children, pregnant women (placental malaria), travelers, immunocompromised.
- Recent developments: Increased focus on elimination, mass drug administration in endemic foci, RTS,S/AS01 malaria vaccine in pilot introduction.
II. Plasmodium Species and Life Cycle
Species | Prevalence | Features |
---|---|---|
P. falciparum | Most common, most severe | Cerebral malaria, severe anemia |
P. vivax | Second most common | Relapses (hypnozoites), broad distribution |
P. ovale | Africa, rare elsewhere | Relapses (hypnozoites) |
P. malariae | Worldwide, low incidence | Chronic/inapparent infection |
P. knowlesi | SE Asia | Severe, zoonotic |
Life Cycle Highlights:
- Sporozoite transmission: Injected via mosquito bite, travel to liver.
- Exoerythrocytic (liver) phase: Cells mature into schizonts, release merozoites.
- Erythrocytic phase: Merozoites invade red blood cells; repeated cycles of lysis cause symptomatic malaria.
- Gametocyte formation: Sexual stages taken up by another mosquito, perpetuating the cycle.
- Hypnozoites: Dormant liver forms (P. vivax, P. ovale) cause late relapses.
III. Clinical Presentation
- Uncomplicated malaria: Periodic fever (classic tertian/quartan cycle), chills, sweats, headache, malaise, myalgia.
- Severe malaria: Confusion, seizures (cerebral), shock and organ dysfunction (renal, hepatic), acidosis, respiratory distress, severe anemia, hypoglycemia (especially children/pregnant women).
- Signs: Splenomegaly, jaundice, dark urine (hemoglobinuria, “blackwater fever”).
IV. Diagnosis
- Microscopy
- Thick and thin blood smears: Gold standard, enables species identification, quantification of parasitemia.
- RDTs (Rapid Diagnostic Tests)
- Detect antigens (HRP2 for P. falciparum, LDH for pan-malarial warning).
- Useful in poor-resource/field settings.
- PCR & Molecular Diagnostics
- High sensitivity/specificity, mostly for research or complex diagnosis.
- Clinical/Ancillary Labs
V. Classification of Severity
- Uncomplicated Malaria: No severe features or organ involvement.
- Severe/Complicated Malaria: Defined by WHO criteria:
VI. Management and Drug Therapy
A. Principles of Management
- Rapid diagnosis and treatment commencement
- Supportive care tailored to severity
- Drug regimens suited to Plasmodium species, resistance profile, and clinical scenario.
B. Antimalarial Drug Classes
Drug/Class | Target Stage | Key Regimens/Uses |
---|---|---|
Artemisinin derivatives | Blood (as ACT) | Artesunate, artemether, DHA |
Quinolines | Blood/hypnozoite | Chloroquine, mefloquine, quinine, primaquine |
Atovaquone-Proguanil | Blood/liver | Malarone |
Sulfadoxine-Pyrimethamine | Blood (partner drug) | SP (still used in IPTp) |
Tetracyclines | Blood (partner drug) | Doxycycline, clindamycin (children/pregnancy) |
First-Line Therapies: Artemisinin-Based Combination Therapies (ACTs)
- Artemether-lumefantrine, artesunate-mefloquine, DHA-piperaquine, artesunate-amodiaquine, artesunate-SP.
- Rapid parasite clearance, efficacy against resistant P. falciparum.
- Administered orally, except IV artesunate for severe malaria.
Non-ACT options (species/region specific):
- Chloroquine (if no resistance for P. vivax, some non-Africa regions)
- Quinine (IV for severe malaria, oral for areas lacking IV artesunate)
- Atovaquone-proguanil (prophylaxis, alternative therapy)
- Mefloquine (prophylaxis, treatment, caution for neurotoxicity)
- Primaquine (radical cure for P. vivax/P. ovale; G6PD testing required)
- Doxycycline/clindamycin (used with quinine or artesunate for severe malaria, or as partner in ACTs; clindamycin preferred in children/pregnancy).
Severe Malaria Management
- IV artesunate is globally preferred over quinine.
- Supportive measures: Correct hypoglycemia, manage fluid/electrolytes, renal support as needed, seizure control, monitor for respiratory distress.
- Exchange transfusion very rarely, for extreme parasite burden.
Special Groups
- Pregnant women: Quinine + clindamycin or ACT, dependent trimester and local guidelines (avoid atovaquone, primaquine).
- Children: Lower thresholds for severe malaria, higher risk; careful monitoring for complications.
- Comorbid diseases (HIV, TB): Account for potential drug interactions.
To learn about the pharmacology of individual drug classes, please refer to this page.
VII. Prevention
A. Vector Control
- Insecticide-treated bed nets (ITNs), indoor residual spraying (IRS).
B. Chemoprophylaxis
- Travelers: Atovaquone-proguanil, doxycycline, mefloquine, and chloroquine (if susceptible region).
- Intermittent Preventive Therapy (IPT): In pregnancy (IPTp), children (IPTi), and infants.
C. Vaccines
- RTS,S/AS01 vaccine: Shown efficacy in children (pilot phase in Africa); ongoing research into broader/more durable vaccines.
D. Personal Protective Measures
- Mosquito avoidance: repellents, clothing, behavior adjustment.
VIII. Drug Resistance
- Chloroquine resistance: Widespread, especially for P. falciparum.
- Artemisinin resistance: Regions of Southeast Asia (K13 mutations, slower clearance), actively monitored worldwide.
- Other resistance: Mefloquine, SP, emerging resistance to ACT partner drugs. Combination therapy crucial for slowing resistance.
IX. Monitoring and Follow-up
- Continue daily blood smears for hospitalized or severe cases to monitor parasite clearance.
- Monitor for relapse in *P. vivax/P. ovale (risk of hypnozoites).
- Supportive lab monitoring (CBC, renal/liver function, glucose, acid-base status).
- Watch for side effects: hemolytic crisis (primaquine), neuropsychiatric symptoms (mefloquine), GI upset (ACTs), allergic reactions.
X. Complications
- Cerebral malaria (ICU care, seizure management)
- Severe anemia (transfusion)
- Acute kidney injury (renal replacement therapy)
- Acute respiratory distress syndrome (supportive care)
- Hypoglycemia (especially in children with quinine, artesunate therapy)
- Splenic rupture, shock, bleeding disorders
- Hyperparasitemia (>10% RBCs).
XI. Summary Table: Drug Choices by Scenario
Situation/Species | First-line | Alternatives/Adjuncts |
---|---|---|
Uncomplicated P. falciparum | ACTs | Atovaquone-proguanil, quinine |
Severe malaria | IV artesunate | IV quinine (where artesunate unavailable) |
Uncomplicated P. vivax/P. ovale | Chloroquine (+ primaquine for radical cure, G6PD tested) | ACTs where chloroquine resistance |
Pregnancy (uncomplicated) | Quinine + clindamycin (first trimester); ACTs (after first) | Mefloquine (where permitted) |
Prophylaxis (travelers) | Atovaquone-proguanil, doxycycline, mefloquine | Chloroquine (susceptible regions) |
Relapse prevention | Primaquine (after G6PD test) | Tafenoquine (where available, G6PD tested) |
References
- Shrestha J, Malaria. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023.
- WHO guidelines for malaria. World Health Organization. 2021, updated Sept 2025.
- Hunsicker LG. The Pharmacology of Antimalarials: A Rational Approach to the Therapy of Resistant Falciparum Malaria. Arch Intern Med. 1969;123(6):645–649.
- Mayo Clinic. Malaria: Diagnosis & treatment. Updated 2023 Feb.
- CDC. General Approach to Treatment | Malaria. 2025 May.
- WHO. New and updated malaria guidance. 2025.
- Malaria Journal. Assessing fitness costs in malaria parasites: implications for drug resistance management. 2025 Feb.
- Tandfonline. A systematic review on malaria and dengue vaccines. 2024 Apr.
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