Practical Medical Biology Lab 13: Haemoflagellates

Haemoflagellates

• Haemoflagellates include Giardia lamblia, Leishmania spp., Trichomonas tenax, Trypanosoma brucei, Trichomonas vaginalis, and Trypanosoma cruzi.

Genus: Leishmania

• Named after Sir William Leishman, who discovered the flagellate protozoa causing Kalaazar, an Indian visceral leishmaniasis.
• All members of the genus Leishmania are obligate intracellular parasites.
• Causes three different diseases: visceral leishmaniasis, cutaneous leishmaniasis, and mucocutaneous leishmaniasis.

Visceral Leishmaniasis

• Caused by L. donovani, infecting internal organs (liver, spleen, and bone marrow) in humans.
• The second-largest parasitic killer in the world, after malaria.

Morphology of Leishmania

• Exists in two forms: amastigote (in humans and other mammals) and promastigote (in the sandfly and in artificial culture).
• Morphological differences between amastigotes and promastigotes:
  • Amastigotes: round or oval shape, non-flagellate, and found in human macrophages.
  • Promastigotes: spindle-shaped, flagellate, and found in the midgut of the sandfly.

Leishmania donovani

• Causes visceral leishmaniosis or Kala-azar, a major public health problem in many parts of the world.
• Vector: female sand fly of the genus Phlebotomus.
• Vertebrate host: humans and other mammals.
• Habitat: obligatory intracellular (mostly macrophages).
• Mode of infection: by vector sand fly bite of exposed skin.
• Clinical features: intermittent fever, weakness, diarrhea, sweating, weight loss, anemia, and granulomatous skin lesions.

Diagnosis of Leishmaniasis

• Based on history of exposure to sand fly.
• Methods:
  • Microscopic examination: demonstration of amastigotes in blood smears and tissue aspirates.
  • Culture: tissue specimens or blood cultured in NNN medium.
  • Serodiagnosis.
  • Molecular diagnosis: PCR on clinical specimens.
  • Skin test: Leishmanin skin test (Montenegro test).

Leishmania tropica

• Includes three species: L. tropica minor, L. tropica major, and L. aethiopica.
• Found in Middle East, India, Afghanistan, eastern Mediterranean countries, North Africa, Ethiopia, and Kenya.
• Causes old world cutaneous leishmaniosis, oriental sore, Delhi ulcer, Baghdad pill, Aleppo pill, and Delhi pill.
• Amastigotes present in the skin, within large mononuclear cells and neutrophils.
• Habitat: human skin.
• Pathogenicity and clinical signs of Cutaneous Leishmaniosis:
  • Most common form.
  • Characterized by one or more sores, papules, or nodules on the skin.
  • Sores can change in size and appearance over time.
  • Often described as looking somewhat like a volcano with a raised edge and central crater.
  • Sores are usually painless but can become painful if secondarily infected.
  • Swollen lymph nodes may be present near the sores.
  • Sores can leave significant scars and be disfiguring if they occur on the face.

This quiz covers the basics of Haemoflagellates, including Giardia lamblia, Leishmania spp, Trichomonas tenax, Trypanosoma brucei, and more. It's a practical lab for Medical Biology students at the College of Dentistry, Alnoor University.