This episode introduces nematodes, or roundworms, the most diverse group of helminths affecting humans. Drawing from Murray’s Chapter 74, it explores their morphology, transmission, and disease patterns.
Nematodes are cylindrical, unsegmented worms with separate sexes. Infection typically occurs through:
Ingestion of eggs (e.g., Ascaris lumbricoides)
Skin penetration by larvae (e.g., hookworms, Strongyloides)
Vector transmission (e.g., filarial worms)
Disease patterns vary by life cycle:
Intestinal nematodes - abdominal pain, obstruction, nutritional impairment
Tissue-migrating larvae - pulmonary symptoms during migration
Filarial infections - lymphatic obstruction and elephantiasis
Eosinophilia is common, especially during tissue migration phases.
Conceptually, nematode disease reflects life cycle movement through the human body. Clinically, timing of symptoms often mirrors migratory stages.
Key Takeaways
Nematodes are cylindrical, unsegmented worms
Transmission may involve ingestion, skin penetration, or vectors
Larval migration can cause pulmonary symptoms
Filarial worms obstruct lymphatics
Eosinophilia is a key laboratory clue
