BOOK QUESTIONS

• Nematodes


  Roundworms, parasites that can cause disease in animals, plants, and humans
• General morphology of nematodes

  • Nonsegmented
  • Cylindrical
  • Bilaterally symmetrical
  • Sexes are separate
  • No circulatory system
  • Complete digestive tract
• Nematode life cycle


  1. Egg

  2. Larva

  3. Adult
• Nematodes can be subdivided into 3 major classifications: intestinal nematodes, vector-borne nematodes, and tissue-dwelling nematodes
• Intestinal nematodes


  • Ascaris lumbricoides
  • Enterobius vermicularis
  • Trichuris trichiura
  • Capillaria philippinensis
  • Ancylostoma duodenale
  • Necator americanus
  • Strongyloides stercoralis
  • Strongyloides fuelleborni
  • Trichostrongylus spp.
  • Anisakis spp.
• Vector-borne nematodes


  • Wuchereria bancrofti
  • Brugia malayi
  • Brugia timori
  • Loa loa
  • Mansonella ozzardi
  • Mansonella streptocerca
  • Mansonella perstans
  • Onchocerca volvulus
  • Dirofilaria spp.
• Tissue-dwelling nematodes


  • Dracunculus medinensis
  • Trichinella spiralis
  • Toxocara canis
  • Toxocara cati
• Enterobius vermicularis infection diagnosis

  Finding eggs in perianal specimens
• Infective stage of Trichuris trichiura in humans

  Embryonated egg
• Characteristics of L3 larva

  • It is the infective stage of Ancylostoma duodenale
  • It has a closed mouth
  • It is the feeding stage of the larva
  • It is also known as the filariform larva
• Intestinal nematode that is larviparous

  Capillaria philipinensis
• Dental pattern of Ancylostoma duodenale

  Semilunar cutting plates
• Characteristics of Strongyloides stercoralis

  • Male S. stercoralis is parthenogenetic
  • Tail of the filariform larva is notched/forked
  • Rhabditiform larva has a small genital primordium
• Causative agent of swollen belly syndrome/sickness

  Strongyloides fuelleborni
• Characteristics of Wuchereria bancrofti microfilaria

  Irregularly spaced nucleus
• Vector of Loa loa

  Mango fly
• Nematode commonly called the blinding worm

  Onchocerca volvulus
• Habitat of adult Trichinella spiralis worms

  Striated muscles
• Reagent for Knott's concentration technique

  1 mL of blood + 10 mL of 2% formalin
• Heartworm of dogs


  Dirofilaria immitis
• Mansonella ozzardi has a subperiodic microfilaria
• Onchocerca volvulus has a nonperiodic microfilaria
• Wuchereria bancrofti has a nocturnal microfilaria
• Loa loa has a diurnal microfilaria
• Female adult worm with a uterus having a characteristic barber's pole appearance

  Trichuris trichiura
• Brugia malayi microfilaria does not have two terminal nuclei
• Schistosoma japonicum


  Parasite that causes schistosomiasis
• Schistosoma haematobium


  Parasite that causes schistosomiasis
• Schistosoma mekongi


  Parasite that causes schistosomiasis
• Schistosoma intercalatum


  Parasite that causes schistosomiasis
• Subcutaneous tissue, liver (sinusoids)

  Locations where trematodes can be found
• Mesenteric veins (vesical, prostatic or uterine veins: S. haematobium)


  Locations where trematodes can be found
• Trematodes, also known as flukes, are part of the phylum Platyhelminthes that can contribute infection to humans either by mechanical obstruction or local inflammatory mechanisms
• Adult trematodes and eggs differ in general morphology and some differ in its life cycle and development
• Larval stages of trematodes

  1. Miracidium

  2. Sporocyst

  3. Redia

  4. Cercaria

  5. Metacercaria
• Miracidium is the infective stage to the 1st intermediate host (snails) and metacercaria found in the 2nd intermediate host is the infective stage to the definitive host and is acquired by ingestion
• For Schistosomal flukes, it is the cercaria that acts as infective stage that is transmitted by skin penetration
• All trematodes require two intermediate hosts to complete its life cycle, except Schistosomes
• All trematode eggs are operculated, except Schistosomes
• All trematodes are hermaphrodite, except Schistosomes that are dioecious