Para PRELIMS (2)

• Intestinal Nematodes


  • Ascaris lumbricoides
  • Trichuris trichiura/Trichocephalus trichiurus
  • Enterobius vermicularis/Oxyuris vermicularis
• Ascaris lumbricoides


  Giant Intestinal roundworm/eelworm

  
• Trichuris trichiura/Trichocephalus trichiurus


  Whipworm
• Enterobius vermicularis/Oxyuris vermicularis


  Pinworm/seatworm
• Ascaris lumbricoides


  • Habitat: Small intestine
  • Clinical Significance: ASCARIASIS, PULMONARY DISORDER
• Trichuris trichiura/Trichocephalus trichiurus


  • Habitat: Large intestine
  • Clinical Significance: Colitis, dysentery, "RECTAL PROLAPSE"
• Enterobius vermicularis/Oxyuris vermicularis


  • Habitat: Large intestine
  • Clinical Significance: Itching & inflammation of anus
• Infective stage


  Embryonated egg
• Mode of Transmission


  Ingestion of fully embryonated egg
• Laboratory Diagnosis for Ascaris lumbricoides

  • Direct Fecal Smear
  • Concentration Tech
  • Kato-Thick smear
  • Kato-Katz
• In Ascaris, pneumonitis can rarely occur and embryos can be found in sputum
• Laboratory Diagnosis for Trichuris trichiura/Trichocephalus trichiurus

  • Finding ova in stool through: Direct Fecal Smear exam, Kato-Thick smear, Kato-Katz, Concentration Technique
• Laboratory Diagnosis for Enterobius vermicularis/Oxyuris vermicularis

  perianal and fingernail scrappings, " Perianal Swab" or Scotch Tape Swab
• Commonality between Hookworm and Strongyloides stercoralis

  • Ova
  • Larvae
  • Adult

  
• Rhabditiform larva


  First stage larva, considered as feeding but non-infective, characterized by an open mouth
• Filariform larva


  Second stage larva, considered a non-feeding but infective, characterized by a closed mouth, longer and more slender than rhabditiform larva
• Hookworm species


  • Ancylostoma duodenale - Old World Hookworm
  • Necator americanus - New World Hookworm
  • Ancylostoma braziliense - Cat Hookworm
  • Ancylostoma caninum - Dog Hookworm

  
• Necator americanus


  • Female: 9-13mm with blunt posterior end
  • Male: 7-11mm having posterior end of fan-like bursa for copulation
  • Buccal capsule contains a pair of ventral and dorsal cutting plates
  • Copulatory bursa contains spicules that are fused distally

  
• Ancylostoma duodenale


  • Buccal capsule contains 2 pairs of large ventral (anterior) teeth
  • Copulatory bursa is at posterior end and contains 2 thin spicules that separate distally
• Hookworm species comparison


  • Necator americanus
  • Ancylostoma duodenale
  • Ancylostoma braziliense
  • Ancylostoma caninum

  
• Symptoms of hookworm infection

  • Dermal: Local erythema, macules, papules (ground itch)
  • Pulmonary: Bronchitis, pneumonitis and, sometimes, eosinophilia
  • Gastrointestinal: Anorexia, epigastric pain and gastro-intestinal hemorrhage
  • Hematologic: Iron deficiency anemia, hypoproteinemia, edema, cardiac failure
• Pathogenesis of hookworm infection

  • Dermal: Cutaneous invasion and subcutaneous migration of larva
  • Pulmonary: Migration of larvae through lung, bronchi, and trachea
  • Gastrointestinal: Attachment of adult worms and injury to upper intestinal mucosa
  • Hematologic: Intestinal blood loss

  
• Identification of Ancylostoma duodenale


  Buccal cavity contains 2 pairs of large ventral (anterior) teeth
• Identification of Necator americanus

  Buccal cavity contains semilunar "no teeth"
• Identification of Ancylostoma caninum


  Buccal cavity contains 3 pairs of teeth
• Treatment for hookworm infection

  • Drugs of choice: albendazole, mebendazole and pyrantel pamoate
  • When indicated, especially in persons with asymptomatic hookworm infection, only iron replacement and/or other dietary therapy (including proteins, iron, and other vitamins) may be administered
• Strongyloides stercoralis is a parasitic nematode that lives threaded into the mucosal epithelium of the human small intestine, with no parasitic male and females reproducing by parthenogenesis

  
• Strongyloides stercoralis female


  Very small (2.1-2.7 mm), slender, and filariform, with a short, pointed tail, rarely seen in feces
• Life cycle of Strongyloides stercoralis

  • Free living: Absence of host
  • Parasitic: Infects susceptible host

  
• Pathogenesis of Strongyloides stercoralis

  • Autoinfection
  • Vietnam / Cochin China diarrhea
  • Honeycomb appearance in intestinal mucosa
  • Pneumonitis
  • Hyperinfection syndromes
  • Disseminated strongyloidiasis
• Dracunculus medinensis


  • Common name: Guinea worm
  • Common associated disease and condition names: Dracunculosis, dracunculiasis, guinea worm infection

  
• Dracunculus medinensis adults


  • Considered as one of the largest adult nematodes, the average elongated female Dracunculus medinensis measures approximately 840 mm long by 1.5 mm wide
• Laboratory Diagnosis for Dracunculus medinensis


  Adult D. medinensis worms may be recovered by observing infected ulcers for the emergence of the worms, induced rupture of the infected ulcers by immersing in cool water reveals the first-stage larvae

  
• Trichinella spiralis


  • "PORK MUSCLE ROUNDWORM or TRICHINA WORM"
  • Infective stage is: ENCYSTED LARVA
  • Mode of Transmission: Acquired through ingestion of encysted larva from inadequately cooked pork

  
• Pathogenesis of Trichinosis


  • Intestinal involvement
  • Larval migration
  • Muscle encystment
• Life cycle of Trichinosis

  1. Acquired by ingesting meat containing the encysted larva

  2. Larva is released from the cyst and invade the small bowel mucosa where they develop into adult worms (4 weeks)

  3. After 1 week, the female releases a larva that migrate to the striated muscles where they encyst (4-5 weeks)

  4. Encysted larva may remain viable for several years

  5. One female worm produces approximately 1500 larva

  
• Laboratory Diagnosis for Trichinella spiralis


  • Examination of the affected skeletal muscle is the method of choice for recovery of the encysted larvae, serologic methods are also available
  • Presence of eosinophilia and leukocytosis
  • Elevated serum muscle enzyme levels, such as lactate dehydrogenase, aldolase, and creatinine phosphokinase, may also aid in T. spiralis diagnosis
• Threadlike nematodes can infect the human lymphatic system, subcutaneous and deep connective tissues, are ovoviviparous, and have microfilariae
• Periodicity


  Activeness at certain time
• Filarial worms


  • Wuchereria bancrofti (Bancroft's Filarial Worm)
  • Brugia malayi (Malayan Filarial Worm)