Clinical Pathological Case Conference Answer

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Strongyloides Stercoralis
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EPIDEMIOLOGY

• 100 millions people infected worldwide
• All tropical and subtropical regions
• Europe (Northern Italy, France, Spain,
• Switzerland, Poland)
• USA (Appalachian region, West Virginia)
• Japan (Okinawa)
• Australia (aboriginal populations

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Unique among the nematode parasites of humans in
that it has a free-living life cycle and an auto
infective cycle in addition to the normal
parasitic type life cycle. Hosts Natural
Humans other primates ,dogs,cats Experimentally G
erbils,Patas monkeys,mice Reproduction Parasitic
adults are parthenogenesis. Free-living adults
are sexual
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• Parasitic female lives in the small intestine in
  the epithelial mucosa and the crypts of
  Lieberkühn.

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Autoinfection

• Some known triggers/inducing conditions
• 1. Corticosteroids (prednisone)
• 2. Immunosuppression
• 3. Neonatal infections
• 4. Infections with transplanted adults
• 5. Massive initial infections
• 6. Intestinal stasis

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Determinants

• 1. Immune status of the host
• 2. Environmental parameters
• 3. Presence of food

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Strongyloides Life Cycle
parthenogenesis
FECES
SOIL
infective larvae
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• Route of migration through the body
• The scramble hypothesis - any route that leads to
  the small intestine.
• Migration starts with a layover in the skin (1
  to 2 days).
• Migration from the skin takes 4 days.
• 5 - 6 days to reach small intestine.
• L4 2days.
• Young adults in intestine at 7 days
  post-infection.
• L1 in feces by 10 to 14 days post-infection.

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Filariform larva (approximately 550 µm in length)
and an immature adult worm (1.3 mm) recovered
from the feces of an immunocompromised dog
experimentally infected with Strongyloides
stercoralis. It is extremely rare to recover from
the stools of immunocompetent patients any S.
stercoralis stages other than the
shorter (approximately 300 µm) and plumper
rhabditiform larvae (right upper corner inset)
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• Eggs are embryonated(L1) when laid.

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Intestinal muscularis mucosae and submucosa with
a full-length section of a penetrating filariform
larva.
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GI Manisfestations

• Epigastric abdominal pain
• Postprandial fullness
• Heartburn
• Brief episodes of diarrhea
• Malabsorption

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Pulmonary manifestations

• Diffuse bronchopneumonia
• Intra-alveolar hemorrrhage

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• Haemoragic pneumonia in disseminated S
  stercoralis infection

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Cutaneous Manifestations

• Uricarial rashes
• Migratory dermatitis
• Periumbilical cutaneous purpura

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• Migrating larvae of Strongyloides stercoralis in
  skin

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Diagnostic challenges

• A fatal disease in immunocompromised and lifelong
  autoinfection
• Intermittent larval excretion
• Insensitivity of standard lab techniques
  (preserved stool concentrations, charcoal
  culture)
• Insensitivity of our best larva finding technique
  (agar plate)
• Non-specificity of standard strongyloides
  serologies

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Strongyloides Stercoralis

• Diagnosis
• Parasite found in feces, sputum, duodenal
  aspiration, CSF, tissue biopsy

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Stronglyoides Infection

• Treatment
• oral Ivermectin 200 ug/kg daily x 2 days,
  Albendazole as alternative
• Prevention
• CDC recommends oral Ivermectin 200 ug/kg daily x
  2 days for prevention in immunosuppressed

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