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Intestinal parasites

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					Intestinal parasites



    Dr Robin Chen
        PYNEH
Classification of Intestinal
Helminths
• Morphology
  –   Protozoa
  –   Nematodes (round worm)
  –   Flatworm
       • Trematodes (flukes)
                                              -->
          – Liver flukes: clonorchis sinensis --> cholangitis
       • Cestodes (tape worm)
                  solium:
          – Tinea solium: Cysticercosis
• Transmission
  – Food-borne helminths
  – Soil transmitted helminths
     • Via food
     • Via skin penetration
Specific symptoms
•   Gut obstruction – Ascaris
•   Acute diarrhoea – Fasciolopsis
•   Persistent diarrhoea – strongyloides / Capillaria
•   Dysentery – trichuris
•   Disseminated infection – strongyloides
•   Biliary symptoms – Opisthorchis, Ascaris
•   Cirrhosis, portal HT - Schistosoma
Common presentation in Thai

• Malnutrition
  – Ascaris Lumbricoides
• Anaemia due to chronic GIB
  – T trichiura / Hookworm
• Immunocompromise host
  – strongiloidosis
Resurgence of strongiloidosis
Strongyloides

• Decreasing prevalence
  – 5-15%


• New challenge
  – Immunocompromised host
Direct life cycle
A1: adult: female worms live in the small intestine
A2: The female worm lay eggs by parthenogenesis
A3: Rhabditiform larva
A4: Filariform larva   lymph pulmonary          GI
A5: Filariform larva penetrates human skin / mucosa


Indirect life cycle
B1: Rhabditiform larvae pass in stool
and grow into adult worms in moist soil
B2: The egg is laid
B3: Rhabditiform larva hatches, molts to
filariform larva

C Autoinfection
Internal infection by filariform larvae
without leaving the host
2 spicules


male         female
Acute strongyloidosis
• Cutaneous Manifestation
  – Ground itch
  – Larva currens
     • tortuous linear urticarial rash
     • around buttock
• Loeffler syndrome
  –   End result of many parasitic infection
  –   Strong allergic reaction to eggs of ascaris
  –   Symptoms similar to asthma
                                 eosinophilia,
       • Fever, cough, wheezing, eosinophilia, haemoptysis
• Epigastric pain, diarrhoea
Chronic strongyloidosis
• Majority asymptomatic
• Classical triad
    – Urticarial rash (recurrent)
    – Abdominal pain
    – Diarrhoea
•   GI: anorexic, vomiting / diarrhoea, constipation
•   Skin: larva currens, pruritis ani, urticaria
•   Resp symptoms
    – similar to asthma
• Usually with eosinophilia
Severe complicated Strongyloidosis

• Hyperinfection
  – Infection confines to gut
  – No criteria : usu. 10,000 per gram of stool
Severe complicated strongyloidosis

• GI complication
  – Pseudo-obstruction, ileus, abd pain
  – Sprue like: steatorrhea, protein losing enteropathy,
    malnutrition
  – Flatulence
  – Fever
  – Hypoalbuminaemia
  – Necrotizing jejunitis / enteritis , massive GIB
Severe complicated Strongyloidosis

• Disseminated strongyloidosis
  – Extra-intestinal organs
  – Sputum examination
     • a few larvae in sputum
        – common in uncomplicated infestation
     • Disseminated disease – high No. larvae
Severe complicated Strongyloidosis

• Pulmonary
  – Pneumonitis / pulmonary haemorrhage
  – ARDS     respiratory failure
  – Resistant to treatment
• Neuro
  – Often due to secondary bacterial infection
  – Meningitis / brain abscess
• Septicaemia
  – Gram –ve including pseudomonas
  – anaerobes
Severe complicated Strongyloidosis

• Autoinfection of filariform larvae
• Predisposition
   –   AIDS
   –   Malignancy (lymphoma, leukaemia)
   –   Steroid therapy
        • Larvae filariform speeds up by steroid
   –   Renal transplant
   –   SLE
   –   Malnutrition
“New face” for strongiloidosis

• Immunocompromise host
  – Severe asthma like disease
     • Worsen with steroid
     • ARDS
  – Severe sepsis

  – Absence of eosinophilia
Thank You

				
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posted:11/24/2011
language:English
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