Malaria

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

To view the entire topic, please or .

Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:

-- The first section of this topic is shown below --

Basics

Description

  • Infection with Plasmodium species protozoa, transmitted to humans by Anopheles species mosquitoes
  • Most morbidity and mortality is caused by Plasmodium falciparum.
  • System(s) affected: cardiovascular, hematologic, renal, respiratory, cerebral, lymphatic, immunologic, hepatic

Epidemiology

  • Cases imported to the U.S.: 68% P. falciparum; 12% Plasmodium vivax; 3% Plasmodium malariae; 5% Plasmodium ovale
  • Malaria is responsible for 1 to 3 million deaths/year (primarily children in sub-Saharan Africa).
  • 300 to 500 million cases annually across the globe
  • Most prevalent in rural tropics (altitude <1,000 m)

Incidence
  • Most U.S. cases (>99%) are imported.
  • There are ~30 million travelers to tropical areas each year. 10,000 to 30,000 travelers from the United States and Europe contract malaria annually.
  • ~2,000 cases and 5 deaths per year in the U.S.
Prevalence
  • Predominant age: all ages
  • Predominant sex: male = female

Etiology and Pathophysiology

  • The human-mosquito life cycle of Plasmodium species is complex and elegant with.
  • Plasmodia are transmitted via saliva from infected Anopheles mosquito during a blood meal. Circulating plasmodia enter red blood cells (RBC), digest RBC proteins, and alter the RBC membrane, causing hemolysis, increased splenic clearance, and anemia.
  • RBC lysis stimulates release of cytokines and TNF-α causing fever and systemic symptoms.
  • P. falciparum alters RBC viscosity, causing obstruction and end-organ ischemia.

Genetics
Unknown, but inherited conditions may affect disease severity and susceptibility (e.g., glucose-6-phosphate dehydrogenase [G6PD] deficiency, sickle cell disease or trait)

Risk Factors

  • Travel to or migration from endemic areas
  • 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 insecticides such as permethrin, and avoid outdoor activity from dusk to dawn (when feeding activity of Anopheles mosquito is the greatest).
  • Malarial chemoprophylaxis in endemic 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 >10 to 20 kg, 1 pediatric tablet daily; children >20 to 30 kg, 2 pediatric tablets daily; children >30 to 40 kg, 3 pediatric tablets daily; children >40 kg, 1 adult tablet daily
      • Contraindicated in pregnant women and infants <5 kg.
    • Chloroquine: Begin 1–2 weeks before arrival and continue for 4 weeks after leaving. Adults, 500-mg salt (300-mg base) weekly; children, 8.3 mg/kg salt (5-mg base/kg) weekly up to 500-mg salt
      • Caution: can make psoriasis worse
    • Doxycycline: Begin 1–2 d before arrival and continue for 4 weeks after leaving area. Adults, 100 mg/d; children >8 years old, 2 mg/kg up to 100/d
      • Caution: Don’t use in pregnant women and children ≤8 years old.
    • Hydroxychloroquine sulfate: Begin 1–2 weeks before arrival and continue for 4 weeks after leaving. Adults, 400-mg salt (310-mg base)/week; children, 6.5 mg/kg salt (5-mg base/kg)/week up to 400-mg salt
    • 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 weekly; 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 dosing
      • Caution: mefloquine-resistant areas; don’t use if history of psychiatric disorders.
    • Primaquine: Begin 1–2 d before arrival and continue for 1 week after leaving area; adults, 30 mg/day; children, 0.5 mg/kg/day up to adult dose
      • Use only in areas endemic for P. vivax
      • Caution: Exclude G6PD deficiency prior to first use, do not use in pregnant women or breastfeeding women unless infant has been tested for G6PD deficiency.
    • Tafenoquine: Take daily 3 days before arrival, weekly during travel, and 1 week after leaving area; adults 200 mg per dose
      • Caution: Exclude G6PD deficiency prior to first use; don’t use if history of psychiatric disorders; don’t use in children; do not use in pregnant or breastfeeding women.

Commonly Associated Conditions

  • Bacterial coinfections sometimes occur.
  • Sickle cell trait confers an element of protection.

-- To view the remaining sections of this topic, please or --

Basics

Description

  • Infection with Plasmodium species protozoa, transmitted to humans by Anopheles species mosquitoes
  • Most morbidity and mortality is caused by Plasmodium falciparum.
  • System(s) affected: cardiovascular, hematologic, renal, respiratory, cerebral, lymphatic, immunologic, hepatic

Epidemiology

  • Cases imported to the U.S.: 68% P. falciparum; 12% Plasmodium vivax; 3% Plasmodium malariae; 5% Plasmodium ovale
  • Malaria is responsible for 1 to 3 million deaths/year (primarily children in sub-Saharan Africa).
  • 300 to 500 million cases annually across the globe
  • Most prevalent in rural tropics (altitude <1,000 m)

Incidence
  • Most U.S. cases (>99%) are imported.
  • There are ~30 million travelers to tropical areas each year. 10,000 to 30,000 travelers from the United States and Europe contract malaria annually.
  • ~2,000 cases and 5 deaths per year in the U.S.
Prevalence
  • Predominant age: all ages
  • Predominant sex: male = female

Etiology and Pathophysiology

  • The human-mosquito life cycle of Plasmodium species is complex and elegant with.
  • Plasmodia are transmitted via saliva from infected Anopheles mosquito during a blood meal. Circulating plasmodia enter red blood cells (RBC), digest RBC proteins, and alter the RBC membrane, causing hemolysis, increased splenic clearance, and anemia.
  • RBC lysis stimulates release of cytokines and TNF-α causing fever and systemic symptoms.
  • P. falciparum alters RBC viscosity, causing obstruction and end-organ ischemia.

Genetics
Unknown, but inherited conditions may affect disease severity and susceptibility (e.g., glucose-6-phosphate dehydrogenase [G6PD] deficiency, sickle cell disease or trait)

Risk Factors

  • Travel to or migration from endemic areas
  • 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 insecticides such as permethrin, and avoid outdoor activity from dusk to dawn (when feeding activity of Anopheles mosquito is the greatest).
  • Malarial chemoprophylaxis in endemic 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 >10 to 20 kg, 1 pediatric tablet daily; children >20 to 30 kg, 2 pediatric tablets daily; children >30 to 40 kg, 3 pediatric tablets daily; children >40 kg, 1 adult tablet daily
      • Contraindicated in pregnant women and infants <5 kg.
    • Chloroquine: Begin 1–2 weeks before arrival and continue for 4 weeks after leaving. Adults, 500-mg salt (300-mg base) weekly; children, 8.3 mg/kg salt (5-mg base/kg) weekly up to 500-mg salt
      • Caution: can make psoriasis worse
    • Doxycycline: Begin 1–2 d before arrival and continue for 4 weeks after leaving area. Adults, 100 mg/d; children >8 years old, 2 mg/kg up to 100/d
      • Caution: Don’t use in pregnant women and children ≤8 years old.
    • Hydroxychloroquine sulfate: Begin 1–2 weeks before arrival and continue for 4 weeks after leaving. Adults, 400-mg salt (310-mg base)/week; children, 6.5 mg/kg salt (5-mg base/kg)/week up to 400-mg salt
    • 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 weekly; 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 dosing
      • Caution: mefloquine-resistant areas; don’t use if history of psychiatric disorders.
    • Primaquine: Begin 1–2 d before arrival and continue for 1 week after leaving area; adults, 30 mg/day; children, 0.5 mg/kg/day up to adult dose
      • Use only in areas endemic for P. vivax
      • Caution: Exclude G6PD deficiency prior to first use, do not use in pregnant women or breastfeeding women unless infant has been tested for G6PD deficiency.
    • Tafenoquine: Take daily 3 days before arrival, weekly during travel, and 1 week after leaving area; adults 200 mg per dose
      • Caution: Exclude G6PD deficiency prior to first use; don’t use if history of psychiatric disorders; don’t use in children; do not use in pregnant or breastfeeding women.

Commonly Associated Conditions

  • Bacterial coinfections sometimes occur.
  • Sickle cell trait confers an element of protection.

There's more to see -- the rest of this entry is available only to subscribers.