Malaria

Geographic:

  • Africa, India, C & S. America, SE Asia – rural, night-biting mosquitoes
  • Malaria should be suspected in patients with any febrile illness after exposure to a region where malaria is endemic

Pathogen:

  • Plasmodium falciparum (most common & most severe)
  • Plasmodium vivax
  • Plasmodium malaraie
  • Plasmodium ovale
  • Plasmodium knowlesi

Incubation Period: 10 days to 40yrs

  • Following the bite of an infected female Anopheles mosquito, the inoculated sporozoites go to the liver within one to two hours. Individuals are asymptomatic for 12 to 35 days (depending on parasite species), until the erythrocytic stage of the parasite life cycle

Recrudescence

  • symptoms return after a symptom-free period. It is caused by parasites surviving in the blood as a result of inadequate or ineffective treatment.

Relapse

  • symptoms reappear after the parasites have been eliminated from blood but persist as dormant hypnozoites in liver cells.
  • Relapse commonly occurs between 8–24 weeks and is commonly seen withP. vivax and P. ovale infections

Reinfection

  • the parasite that caused the past infection was eliminated from the body but a new parasite was introduced.

Clinical Manifestations

  • The classic symptom of malaria is Paroxysm 
    • a cyclical occurrence of sudden coldness followed by shivering and then fever and sweating,
    • Q2d (tertian fever) in P. vivax and P. ovale infections, and
    • Q3d (quartan fever) for P. malariae.
    • P. falciparum infection can cause recurrent fever every 36–48 hours or a less pronounced and almost continuous feverFever, flu-like illness (shaking chills, headache, muscle aches, fatigue)
  • Nausea, vomiting, diarrhea, jaundice, anemia
  • The initial symptoms and signs of malaria are nonspecific
    • tachycardia, tachypnea, chills, malaise, fatigue, diaphoresis (sweating), headache, cough, anorexia, nausea, vomiting, abdominal pain, diarrhea, arthralgias, and myalgias.
  • Plasmodium falciparum: (severe) kidney failure, seizures, mental confusion, prostration, coma, death, respiratory failure

Dx:

  • Thick and thin blood smear x 3
  • Antigen detection PCR (research tool mostly)
DDx
  • viral infection, meningitis, pneumonia, bacteremia, leptospirosis, typhus, and enteric fever
  • Malaria can coexist with these entities and with HIV, malnutrition, and intestinal geohelminths

Complicated or severe malaria

  • Acute malaria with inability to drink, eat, or sit
  • there may be hyperparasitemia (≥5 to 10 percent of red blood cells [RBCs] infected) and/or major signs of organ dysfunction.
  • Features of complicated malaria may include cerebral malaria, hypoglycemia, acidosis, renal impairment, noncardiogenic pulmonary edema, anemia and other hematologic abnormalities, liver dysfunction, and concomitant infection.
  • Common manifestations among children include convulsions, coma, hypoglycemia, metabolic acidosis, severe anemia, and neurodevelopmental sequelae.
  • Findings observed more frequently among adults include severe jaundice, acute renal failure, and acute pulmonary edema.

Tx:

  • Artesunate (for severe disease) + malarone, doxycycline, or clindamycin
  • Quinine sulfate + doxycycline or clindamycin
  • Chloroquine + primaquine

Reference:

TN2013

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Posted in 93 Travel Medicine, 99 Priority Topics, FM 99 priority topics, ID

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