L2 : Nematodes

• Nematodes - most worm-like of all helminths, elongated, cylindrical, unsegmented worms with tapering ends
• Nematode - means thread-like
• nema means thread
• Nematodes life cycle :

  1. Ova egg - fertilized, unfertilized
  2. Larval stage - (happens outside the ova) larval stages, larval form
  3. Adult formation - diagnostic stage
• Larval stages - L1, L2, L3, L4
• Larval form - (L1, L2) Rhabditiform , (L3, L4) Flariform
• Rhabditiform - feeding stage, asexual phase
• Flariform - developing, infective, infective stage ; asexual phase
• Nematodes :

  1. Ascaris Lumbricoides
  2. Trichuris Trichiura
  3. Hookworms
  4. Strongyloides Stercoralis
  5. Enterobius Vermicularis
  6. Capillaria Philippinensis
  7. Dracunculus Medinensis
  8. Anisakis SPP
  9. Toxocara Spp
• Ascaris Lumbricoides - common name : large intestinal roundworm, roundworm of man
• Ascaris Lumbricoides - causes : ascariasis, roundworm infection
• Ascaris Lumbricoides - a soil transmitted helminth, considered as the most common intestinal helminth infection in the world
• Ascaris Lumbricoides : Unfertilized egg stage

  
• Ascaris Lumbricoides : unfertilized egg stage parameter :

  • Size - 85 to 95 um by 38 to 45 um
  • Shape - varies
  • Embryo - unembryonated, amorphous mass of protoplasm
  • Shell - thin
  • Other - usually, corticated

  
• Ascaris Lumbricoides : fertilized egg stage

  
• Ascaris Lumbricoides : Fertilized egg stage Parameter

  • Size - 40 to 70 um by 30 to 50 um
  • Shape - rounder than non-fertilized
  • Embryo - underdeveloped unicellular embryo
  • Shell - thick chitin
  • Other - maybe corticated or decorticated

  
• Ascaris Lumbricoides: Adult Stage

  
• Ascaris Lumbricoides : Adult stage Parameter

  FEMALE

  • size - 22 to 35 cm
  • color - cream white, pink tint
  • other features - pencil lead thickness

  MALE

  • size - up to 30 cm
  • color - cream white, pink tint
  • other features - prominent incurved tail

  
• Ascaris Lumbricodes Pathophysiology :

  1. Ascariasis
  2. Usual infection of 10 to 20 worms may not show symptoms
  3. Causes Ascaris Pneumonitis: chest pain, cough, fever, increased eosinophil (with heart to lung migration)
  4. Lung infiltration, asthmatic attacks and edema of the lips
  5. Difficulty in breathing
  6. Treatment : Albendazole and Mebendazole
• Ascaris Lumbricoides Life Cycle

  
• Trichuris Trichiura common name - whipworm
• Trichuris Trichiura causes - trichuriasis or whipworm infection
• Trichuris Trichiura : Egg stage - looks like a football shaped and referred to as a Japanese lantern ovum / ova

  
• Bipolar hyaline polar plug - prevents desiccation (desiccation - removal of moisture)
• Trichuris Trichiura : Egg stage parameter

  • size - 50 to 55 by 25 um
  • shape - barrel, football, hyaline polar plug at each end
  • embryo - unicellular, underdeveloped
  • shell - smooth yellow-brown color because of bile duct

  
• Trichuris Trichiura : Adult stage parameter

  • size - 2.5 to 5cm long (males usually smaller than females)
  • anterior end - colorless, resembles a whip-handle, contains slender esophagus
  • posterior end - pinkish gray, resembles whip itself, contains digestive and reproductive systems / males : prominent curled tail

  
• Trichuris Trichiura - 3rd most common helminth ; found primarily in warm climates, poor sanitation practices
• Trichuris Trichiura Symptoms (Children) : ulcerative colitis, chronic dysentery, severe anemia and possibly growth retardation
• Trichuris Trichiura Symptoms (Adult) : inflammatory bowel disease, weight loss, weakness and mucoid or bloody diarrhea
• Trichuris Trichiura Life cycle

  
• Hookworms - refers to two organisms :

  1. Ancylostoma duodenale
  2. Necator americanus
• Hookworms - soil transmitted helminths, blood sucking nematodes that attach to the mucosa of the small intestines
• Ancylostoma duodenale: Egg stage

  
• Ancylostoma duodenale common name - old hookworm
• Ancylostoma duodenale causes - hookworm infection, ancylostomiasis
• Ancylostoma duodenale : Egg stage parameter

  • size - 55 to 60 um
  • width - 35 to 40 um
  • shell - colorless

  
• Necator americanus : Egg stage

  
• Necator Americanus common name : new world hookworm
• Necator americanus causes - hookworm infection, necotoriasis
• Necator americanus : Egg stage parameter

  • size - 60 to 75 um
  • width - 35 to 40 um
  • shell - colorless