Usefulness of Antibody Detection in the Diagnosis of Malaria Parasites

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Usefulness of Antibody Detection in the Diagnosis
of Malaria Parasites

• Marianna Wilson
• Reference Immunodiagnostic Lab
• Division of Parasitic Diseases, CDC

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Types of Serological Assays Malaria
Antibody Detection Indirect Fluorescent
Antibody Enzyme immunoassays Antigen
Detection Immunochromatographic
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Antibody Detection
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Antibody Detection
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Indirect Fluorescent Antibody (IFA)
Microscope slide
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Enzyme Immunoassay (EIA/ELISA)
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ELISA
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Antigen Detection
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Antigen Detection
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Antigen DetectionMalaria Immunochromatographic
Dipstick
OptiMAL Assay
P. falciparum specific monoclonal antibody
Control
Plasmodium pan specific monoclonal antibody
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Antigen DetectionMalaria Immunochromatographic
DipstickProblems

• Low sensitivity with parasites density lt100/ml
• Currently only useful for detection of
  P. falciparum infections
• Moody, Clin Microbiol Rev 20021566-78

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Diagnostic Toolsfor Human Infections with Malaria

• Blood film examination
• Serology - IFA
• PCR

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Malaria IFA Test

• Sensitivity 98
• Specificity 99.5
• Sulzer et al, Am J Trop Med Hyg 196918199-205
• Sulzer et al, Bull Wld Hlth Org 197145375-379

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P. malariae
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P. malariae
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P. malariae
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P. falciparum
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P. falciparum
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P. falciparum
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Malaria IFA TestInitial detection of antibodies

• Parasitemia precedes antibody
• P. vivax 2-6 days
• P. falciparum and P. malariae 4-6 days
• If parasitemia is suppressed by treatment, may
  develop detectable antibody

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Malaria IFA TestDetermination of Infecting
Species

• Non-Immune
• Samples drawn 0-14 days post onset Highest titer
  was to the infecting species in 81
• Samples drawn 15-60 days post onset Highest
  titer was to the infecting species in 96

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Malaria IFA TestDetermination of Infecting
Species

• Is possible in non-immune individuals with
  primary infection.
• Is NOT possible in immune individuals because
  their antibody response reflects multiple
  infections with multiple species.

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Malaria IFA TestAntibody Persistence after
Treatment

• Non-Immunes (Vietnam Vets with Pv)
• 53 IFA negative at 6 mo. post-Rx
• 59 IFA negative at 12 mo. post-Rx
• Wilson et al, Am J Trop Med Hyg 197019401-404

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Malaria IFA TestAntibody Persistence
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Malaria IFA Results
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Sensitivity of Tools forDiagnosis of Malarial
Infection

• Most sensitive
• Antibody detection
• 2. PCR
• 3. Blood film examination

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Diagnosis of Untreated Acute Malaria

• Blood film examination
• PCR

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Diagnosis of Treated Recent Malaria

• Serology
• Blood film examination
• PCR

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Diagnosis of Chronic Malaria

• Screen with serology
• If IFA positive
• May do blood film examination
• May do PCR