parasitology

1) Laboratory Diagnosis in Leishmaniasis:

  • Microscopy:

    • Smear is made from the indurated edge of a nodule or sore and stained by Giemsa.

    • Amastigotes are found in large numbers inside macrophages.

    • Definitive diagnosis is made by demonstration of amastigotes inside macrophages collected from the lesion.

  • Culture:

    • Promastigote form can be isolated by culture of aspirated material in NNN or RPMI + 10% FBS.

  • Skin Test:

    • Leishmanin skin test is helpful. A positive leishmanin test in individuals from endemic areas is highly suggestive of the disease.

    • The test is negative in diffuse cutaneous leishmaniasis (CL).

  • Serology:

    • Used to detect antibodies or antigens produced in response to Leishmania infection.

2) Laboratory Diagnosis in Trichinosis:

  • Direct Methods:

    • Muscle Biopsy:

      • Demonstrates larvae in muscle tissue.

      • Pathognomonic of infection.

    • Stool Examination:

      • May demonstrate adult worms or larvae.

  • Indirect Methods:

    • History:

      • History of consumption of raw or inadequately cooked pork.

    • Serology:

      • ELISA, latex agglutination, or complement fixation tests detect antibodies.

    • Radiology:

      • Calcified cysts can be detected on X-ray.

    • Biochemical:

      • Elevated levels of muscle enzymes (e.g., phosphatase, creatine kinase, lactate dehydrogenase).

    • Benton Test:

      • Positive for years after infection.

    • Differential Diagnosis:

      • Eosinophilia (20-50%) is a strong indicator.

3) Laboratory Diagnosis in Trichocephaliasis:

  • Microscopy:

    • Stool examination for eggs with characteristic bipolar plugs.

  • Rectal Prolapse:

    • Sigmoidoscopy may detect adult worms in the colon.

  • Other Findings:

    • Eosinophilia may also be present but is not specific.

4) Laboratory Diagnosis in Tapeworms:

  • Stool Examination:

    • Detects eggs or proglottids (segments) of worms.

  • Antigen-Based Tests:

    • ELISA, EITB, and IHA are more sensitive than microscopy.

  • Imaging:

    • Ultrasound, CT, or MRI helps identify larval forms.

  • Biopsy or Endoscopy:

    • May be required for larval forms.

  • Molecular Diagnosis:

    • Performed using DNA probes and PCR.

5) Laboratory Diagnosis in Malaria:

  • Microscopy:

    • Blood smear preparation (thin and thick) stained with Giemsa or Leishman stain.

  • Rapid Diagnostic Tests (RDTs):

    • Immunochromatographic tests (ICT) detect malaria antigens.

  • Molecular Diagnosis:

    • DNA probe-based techniques or PCR.

  • Additional Tests:

    • HRP2 and LDH tests for species differentiation.

6) Laboratory Diagnosis in Oxyuriasis:

  • Perianal Tape Test:

    • Adhesive tape is applied to the perianal area and examined microscopically for pinworm eggs.

  • Microscopy:

    • Stool samples may also be used to detect adult worms or eggs, though less reliable.

7) Role of Parasitological and Microbiological Investigations:

  • Parasitological Diagnosis in Vaginal Infections:

    • Direct microscopic examination detects pathogens like Trichomonas vaginalis.

    • Candida species can be identified through culture or wet mount microscopy.

8) Laboratory Diagnosis in Toxoplasmosis:

  • Microscopy:

    • Detects tachyzoites or cysts in blood, sputum, or bone marrow.

  • Serodiagnosis:

    • Detects IgG and IgM antibodies using ELISA.

  • Molecular Diagnosis:

    • PCR for confirmation.

  • Imaging:

    • CT or MRI for CNS involvement or congenital toxoplasmosis.

9) Importance of Stool Examination in Intestinal Parasitosis:

  • Detects eggs, larvae, cysts, or trophozoites of intestinal parasites.

  • Helps assess intensity, duration, and chronicity of infections.

  • Supports public health monitoring and promotes early intervention.

10) Laboratory Diagnosis in Giardiasis:

  • Microscopy:

    • Detects Giardia cysts or trophozoites using trichrome stain or wet mounts.

  • Serological Tests:

    • Antigen detection by ELISA or immunofluorescence.

  • Molecular Diagnosis:

    • DNA probes or PCR.

  • Severe Cases:

    • Duodenal biopsy may confirm diagnosis.

11) Laboratory Diagnosis in Ascariasis:

  • Microscopy:

    • Stool examination detects Ascaris eggs with a thick, mammillated shell.

  • Advanced Techniques:

    • Fecal flotation or sedimentation to enhance egg detection.

  • Serology:

    • ELISA tests may detect antibodies or antigens.

  • Complicated Cases:

    • Imaging (X-ray, ultrasound) for intestinal obstruction or migration.

12) Laboratory Diagnosis in Genital Trichomoniasis:

  • Microscopic Examination:

    • Wet mount of vaginal or urethral discharge detects motile trophozoites.

  • Culture:

    • Specialized culture methods increase sensitivity.

  • Antigen Detection:

    • ELISA or immunochromatographic tests are available.

  • Molecular Diagnosis:

    • PCR for Trichomonas vaginalis DNA is highly sensitive.

    • Helps confirm infection and guide treatment.Other molecular techniques, such as nucleic acid amplification tests (NAATs), can also be utilized for accurate detection.