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Malaria

Malaria is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • Acute or chronic infection transmitted to humans by Anopheles spp. mosquitoes
  • Most morbidity and mortality is caused by Plasmodium falciparum. An estimated 212 million cases occur annually, including 429,000 deaths, most of which occur in children <5 years of age in sub-Saharan Africa (1).
  • Nonimmune individuals are most susceptible to rapid progression to severe disease.
  • System(s) affected: cardiovascular, hematologic, renal, respiratory, cerebral, lymphatic, immunologic

Epidemiology

  • Cases imported to the United States: 66% P. falciparum; 13% Plasmodium vivax; 3% Plasmodium malariae; 5% Plasmodium ovale; 1% mixed; 12% unknown
  • Occurs worldwide in tropical latitudes: P. falciparum, P. malariae, P. vivax, and P. ovale; Plasmodium knowlesi in parts of Southeast Asia

Incidence
  • Most U.S. cases (>99%) are imported.
  • ~1,700 cases and 5 deaths per year in the United States (2)
Prevalence
  • Predominant age: all ages
  • Predominant sex: male = female

Etiology and Pathophysiology

  • Malarial parasites digest red blood cell (RBC) proteins and alter the RBC membrane, causing hemolysis, increased splenic clearance, and anemia.
  • RBC lysis stimulates release of cytokines and tumor necrosis factor (TNF-α) causing fever and systemic symptoms.
  • P. falciparum alters RBC viscosity, causing obstruction and end-organ ischemia.

Genetics
Unknown genetic predilection, but inherited conditions may affect disease severity and susceptibility (glucose-6-phosphate dehydrogenase deficiency, sickle cell disease or trait, and hereditary elliptocytosis).

Risk Factors

  • Travel to or migration from endemic areas (primarily sub-Saharan Africa)
  • Rarely, blood transfusion, mother-to-fetus transmission, and local autochthonous transmission

General Prevention

  • Mosquito avoidance: Use insect repellent, wear clothing to cover exposed skin, use mosquito nets treated with permethrin, and avoid outdoor activity from dusk to dawn.
  • Malarial chemoprophylaxis when in endemic area
    • Mefloquine: Begin at least 2 weeks before arrival and continue for 4 weeks after leaving area. Adults, 250 mg (1 tablet) weekly; children ≤9 kg, 5 mg/kg; children >9 to 19 kg, 1/4 tablet weekly; children >19 to 30 kg, 1/2 tablet weekly; children >30 to 45 kg, 3/4 tablet weekly; children >45 kg as adult
      • Caution: mefloquine-resistant areas
    • Atovaquone/proguanil: Begin 1 to 2 days before arrival and continue for 1 week after leaving area. Adults, 1 adult tablet daily; children 5 to 8 kg, 1/2 pediatric tablet daily; children 9 to 10 kg, 3/4 pediatric tablet daily; children 11 to 20 kg, 1 pediatric tablet daily; children 21 to 30 kg, 2 pediatric tablets daily; children 31 to 40 kg, 3 pediatric tablets daily; children >40 kg, 1 adult tablet daily
    • Doxycycline: Begin 1 to 2 days before arrival and continue for 4 weeks after leaving area. Adults, 100 mg daily; children, 2 mg/kg up to 100 mg daily (not for children <8 years old)
    • Chloroquine: Begin 1 to 2 weeks before arrival and continue for 4 weeks after leaving area. Adults, 500 mg (300-mg base) weekly; children, 8.3 mg/kg (5-mg base/kg) weekly up to 300 mg
      • Caution: chloroquine-resistant areas
    • Primaquine: Begin 1 to 2 days before arrival and continue for 1 week after leaving area; adults, 30 mg/day; children, 0.5 mg/kg/day up to adult dose
      • For use only in areas predominantly endemic for P. vivax
      • Caution: Glucose-6-phosphate dehydrogenase deficiency must be excluded prior to first use.

Commonly Associated Conditions

Bacterial coinfections sometimes occur.

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Citation

Stephens, Mark B., et al., editors. "Malaria." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116364/all/Malaria.
Malaria. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116364/all/Malaria. Accessed April 19, 2019.
Malaria. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116364/all/Malaria
Malaria [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 19]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116364/all/Malaria.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Malaria ID - 116364 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116364/all/Malaria PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -