Laboratory Diagnosis

Also written as VZV.

In laboratory diagnosis of leishmaniasis, the expected parasite stage in vitro (culture) is:

Microscopy (Gram Stain): Direct examination of clinical samples (e.g., sputum, CSF, blood cultures) reveals Gram-positive, lancet-shaped diplococci, providing a rapid presumptive diagnosis.
Culture: Isolation of S. pneumoniae from sterile sites (blood, CSF, pleural fluid) or non-sterile sites (sputum, middle ear fluid) is the gold standard. Grows on blood agar (alpha-hemolysis). Confirmed by optochin sensitivity and bile solub
Urine Antigen Test: Rapid immunochromatographic test detecting pneumococcal C-polysaccharide antigen. Highly specific and moderately sensitive, useful for pneumonia and meningitis, even after antibiotic initiation.
CSF Antigen Test: Can also be performed on CSF for meningitis diagnosis.
Molecular Methods (PCR): Polymerase chain reaction (PCR) assays rapidly detect pneumococcal DNA in various clinical samples (e.g., CSF, blood, respiratory secretions), offering high sensitivity and specificity, especially when culture resul

Specimen: Vesicular fluid, corneal scrapings
Tzanck Smear — from base of vesicle; Wright stain shows multinucleated giant cells with "ground glass" chromatin (Tzanck cells)
Direct Immunofluorescence — monoclonal antibodies conjugated with fluorescent dye; viral inclusion bodies appear as bright green intranuclear particles under UV microscope
Viral Isolation — tissue culture (human diploid fibroblasts, human amnion, human embryonic kidney); cytopathic effect (syncytium formation) seen in 24–48 hours
Serology — IgM detection; useful for primary infection diagnosis

Specimen: Saliva, peripheral blood, lymphoid tissue
Absolute lymphocytosis with atypical lymphocytes (Downey cells)
Direct Immunofluorescence: Monoclonal antibodies conjugated with fluorescent dye on cell scrapings
Heterophil antibody test (non-specific): Patients develop transient antibodies that agglutinate sheep RBCs — detected by Paul-Bunnell test or Monospot test
Specific antibody detection (ELISA or indirect IF):

Specimen: Urine, saliva, peripheral blood mononuclear cells (PBMCs)
Microscopy: Multinucleated giant cells with characteristic intranuclear inclusions — "Owl's Eye" appearance (pathognomonic)
Direct Immunofluorescence and ELISA: Detection of viral antigens
PCR: Detection of CMV DNA (most sensitive, used for monitoring viral load in transplant patients)

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In laboratory diagnosis of leishmaniasis, the expected parasite stage in vitro (culture) is: (Hematopathology MCQs & Essays: MBChB Exam Revision Guide)
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