Parasitic and Protozoal Infections

Parasitic Infections

Protozoal Infection 

Amebiasis and Infection with Free-Living Amebas 

61 yo Male patient who had recently visited Cameroon is admitted for fever that occurs twice a day, peaks 102 F, and is associated with diaphoresis. 
Bands 34, Platelet 29. PT/INR is normal. Few shistocytes are seen. Cr is normal. Mental status is normal. Bi is normal. What should be done in the management of the patient? 

Facts about Malaria
  • 2000 death / day due to Malaria worldwide, 3 billion people live in endemic areas
  • Species
    • P. falciparum (cause of most death)
    • P. vivax (Can cause severe illness)
    • two morphologically identical sympatric species of P. ovale (as suggested by recent evidence), 
    • P. malariae, and
    • in Southeast Asia—the monkey malaria parasite P. knowlesi (Can cause severe illness)

  • Pathogenesis and Life cycle 
    • Stage in the liver for vivax and ovale is hypnozoites.

Diagnostic Tests (U.S)
  • Microscopy
  • Rapid Diagnostic Tests
  • Drug Resistance Testing: CDC recommends all cases of malaria diagnosed in the United States should be evaluated for evidence of drug resistance.
  • Species confirmation and Drug Resistance Testing at CDC: Laboratories that have diagnosed a case of malaria should send a pre-treatment whole blood sample (EDTA) to CDC for species confirmation and evaluation for emerging drug resistance. This testing is provided free of charge and CDC will send results back to the submitter.
  • Ref:
Treatment (U.S): 3 guiding principles
  • Identify the species (3 reasons)
    • Firstly, P. falciparum and P. knowlesi infections can cause rapidly progressive severe illness or death while the other species, P. vivax, P. ovale, or P. malariae,are less likely to cause severe manifestations. 
    • Secondly, P. vivax and P. ovale infections also require treatment for the hypnozoite forms that remain dormant in the liver and can cause a relapsing infection. 
    • Finally, P. falciparum and P. vivax species have different drug resistance patterns in differing geographic regions. For P. falciparum and P. knowlesi infections, the urgent initiation of appropriate therapy is especially critical.
  • Identify the drug susceptibility of the infecting parasites
  • Identify the clinical severity of illness
    • Uncomplicated: Can be treated with oral medications
    • Complicated or severe (if any of the following is present) : Treated inpatient with IV medications
      • impaired consciousness/coma, 
      • severe normocytic anemia [hemoglobin < 7], renal failure, 
      • acute respiratory distress syndrome, 
      • hypotension, 
      • disseminated intravascular coagulation, 
      • spontaneous bleeding, 
      • acidosis, 
      • hemoglobinuria, 
      • jaundice, 
      • repeated generalized convulsions, and/or 
      • parasitemia of ≥ 5%
    • Ref:
  • Treatment summary in decision tree form (CDC)
  • Guidelines for Treatment of Malaria in the United States CDC 2013
  • How to report a Malaria case to CDC

Chagas Disease and African Trypanosomiasis
Toxoplasma Infections
Protozoal Intestinal Infections and Trichomoniasis