Malaria

1. See Also
   1. Malaria Chemoprohylaxis
   2. Vector-Borne Infection
   3. Prevention of Vector-borne Infection
2. Etiology
   1. Plasmodium vivax
   2. Plasmodium ovale
   3. Plasmodium falciparum
   4. Plasmodium malariae
3. Pathophysiology
   1. See Vector-Borne Infection
   2. Transmitted by bite of anopheline (or anopheles) Mosquito
      1. Usually bites between dusk and dawn
      2. Injects Malaria protozoa from Salivary Glands
   3. Species of Malaria
      1. Plasmodium falciparum (most life threatening)
      2. Plasmodium vivax
      3. Plasmodium malariae
      4. Plasmodium ovale
      5. Plasmodium knowlesi
   4. Life cycle of Malaria
      1. Injected from Mosquito as sporozoite
      2. Sporozoites invade hepatocytes
      3. Released into blood stream as merozoites
      4. Merozoites invade erythrocytes and circulate freely
         1. Results in Red Blood Cell lysis
      5. Sporozoites may lie dormant in liver (hypnozoites)
         1. Occurs with Plasmodium vivax and Plasmodium ovale
         2. Symptoms recur when reactivates in months to years
      6. Circulating merozoites differentiate into Gametocytes
         1. Gametocytes are the sexual form of plasmodium
         2. Mosquito ingests gametocytes from infected host
         3. Protozoa develop within the Mosquito over a 10-21 day course
         4. Mosquito infects next human host with bite
4. Epidemiology
   1. Incidence
      1. Most common life threatening disease for travelers
      2. Mosquito population is expected to as much as double with global warming (0.4 C) by 2020
      3. European, North American traveler cases: 30,000/year
      4. Cases reported to CDC per year: 1500
      5. Worldwide Infections: 300 million per year
      6. Worldwide Mortality: 1-3 million deaths per year
   2. Timing
      1. Majority of Malaria outbreaks occur between May and December
      2. Highest risk is during and after the rainy season
         1. River beds and stagnant pools of water are most common breading grounds
   3. Regions
      1. Endemic to tropical and subtropical world (106 countries as of 2010)
      2. Highest Risk
         1. Sub-Saharan Africa
         2. Papua New Guinea
         3. Solomon Islands
         4. Vanuatu
      3. Intermediate Risk
         1. Haiti
         2. Indian subcontinent
      4. Low Risk
         1. Southeast Asia
         2. Latin America
5. Symptoms
   1. Initial prodrome
      1. Headache
      2. Malaise
   2. Soon later
      1. Fever
      2. Shaking chills
   3. Soon later
      1. Drowsiness
      2. Lethargy
6. Signs
   1. Fever for 1-8 hours
   2. Fever recurs
      1. Plasmodium vivax: 48 hours
      2. Plasmodium malariae: 72 hours
      3. Plasmodium falciparum: Variable
   3. Tender Splenomegaly
7. Labs
   1. Complete Blood Count (CBC)
      1. Hemoglobin or Hematocrit consistent with Anemia
   2. Urinalysis
      1. Urobilinogen positive
8. Diagnosis
   1. Peripheral Blood Smear with Giemsa or Wright stain
      1. Gold standard for diagnosis
      2. Examine new smear every 12-24 hours for 3 days
      3. Sample is best obtained when patient is febrile
      4. Image
         1. 
   2. Rapid blood dipstick testing (when smear not available)
      1. HRP-2 detection (only detects P. falciparum)
      2. LDH detection (detects all 4 Malaria types)
9. Management
   1. Chemoprophylaxis
      1. See Malaria Chemoprophylaxis
   2. Treatment (see specific medications for dosing)
      1. Mefloquine
      2. Pyrimethamine with sulfadoxine (Fansidar)
      3. Primaquine
10. Prevention
    1. See Malaria Chemoprophylaxis
    2. See Prevention of Vector-borne Infection
    3. Malaria Vaccine (investigational in 2012)
    4. Stay in air conditioned or well screened rooms
    5. Reduce nighttime outdoor activity (Dusk until dawn)
    6. Apply an effective insect repellent
       1. DEET 30% to skin every 3-4 hours or
       2. p-Menthane-3,8-diol (PMD)
    7. Spray clothing and bed nets with Permethrin
    8. Wear long sleeve shirt and pants
    9. Use insecticide aerosols at dusk in living areas
    10. Use a strong fan at bedside
    11. Use Mosquito bed netting even in hotel rooms
        1. Mosquito net pre-treated with Permethrin
        2. Reapply Permethrin every 6 months
11. Prognosis
    1. Plasmodium falciparum Mortality: 4% (20% severe cases)
12. Resources
    1. See Travel Resources
    2. CDC Malaria hotline (physicians)
       1. Phone: 855-856-4713
    3. CDC Malaria
       1. http://www.cdc.gov/malaria
    4. Malaria Foundation International
       1. http://www.malaria.org
13. References
    1. Baird (1999) Med Clin North Am 83(4):923-44
    2. Croft (2000) BMJ 321(7254):154-60
    3. Lo Re (2003) Am Fam Physician 68(3):509-16
    4. Johnson (2012) Am Fam Physician 85(10): 973-7