Filarial Worms and Microfilaria Quiz

Filarial Worm & Other Tissue Nematodes

• Adult worms live in lymphatic, subcutaneous tissue, connective tissue, muscle, or body cavities.
• Filarial worms are viviparous.
• Transmission requires an intermediate host (vector).
• The first stage larva of the filarial worm is called microfilaria.

Microfilaria Periodicity

• Microfilaria of pathogenic filarial worms exhibit periodicity, an adaptation related to mosquito bites.
• Nocturnal periodicity: Microfilaria are found in greater numbers in peripheral blood during the night.
• Diurnal periodicity: Microfilaria are found in greater numbers in peripheral blood during the day.
• Non-periodicity: Microfilaria circulate at a constant level throughout the day and night.

Wuchereria bancrofti

• Causes lymphatic filariasis.
• Other names for the disease are Wechereiasis, Buncroften filariasis, or Elephantiasis.
• Widely distributed in Asia, America, and Africa.
• Habitat: Lymphatics
• Intermediate host: Culex, Ades, and Anopheles mosquitos
• Commonly affects lower extremities, and may involve genitals and breasts.
• Adult worms are thread-like; males have a curved tail (40 mm), females (80-100 mm).
• Adults typically remain coiled together in lymph vessels and nodes.

Microfilaria (L1) Morphology

• Sheathed.
• Rounded anteriorly and pointed posteriorly.
• Few body kinks, no nuclei at the tail tip.
• Diagnostic stage.
• Nocturnal periodicity.

Lab Diagnosis

• Blood examination:
  • Nocturnal blood collection (22:00–04:00) or use diethylcarbamazine to stimulate circulation
  • Wet preparation (motile microfilaria)
  • Thick and thin blood films (Giemsa stain and hematoxylin)
• Knott's centrifugation technique: Mix blood with a lysing agent, centrifuge to concentrate microfilaria, facilitating detection.

Urine Sample of Wuchereria bancrofti

• Chyluria: Lymphatic fluid (chyle) leakage into the urine, associated with W. bancrofti infection.
• Urine Examination
  • Milky appearance: Cloudy urine due to chyle presence
  • Urine Sediment Test: Microscopic examination of urine sediment identifies fat droplets or lymphocytes.

Additional Diagnostic Methods

• Hydrocele fluid and lymph aspiration— as urine.
• ICT (immunochromatographic test)
• ELISA (enzyme-linked immunosorbent assay)
• Molecular methods.
• Xenodiagnosis.

Pathology

• Inflammatory reaction: Sensitivity to living and dead adult worm products leads to fever, chills, headache, acute lymphangitis in the spermatic cord, and orchitis (inflammation of testes).
• Obstructive filariasis: Acute inflammation at the end converting to granuloma, damages lymphatic tissue, causing fibrosis, edema, and enlargement (elephantiasis).

Test your knowledge on filarial worms and their life cycles, focusing on Wuchereria bancrofti and microfilaria periodicity. This quiz covers their habitat, transmission methods, and related diseases. Suitable for students of parasitology and related fields.