Strongyloidiasis (Threadworm in-fection)

Notes
  • It is caused by Strongyloides stercoralis or threadworms.
  • It is arguably the most neglected tropical disease (NTD)
  • Their life-cycle is very similar to that of the hookworms with the difference being the high level of auto-infection in S. This auto-infection can lead to hyperinfection, especially in immunocompromised subjects, and disseminated strongyloidiasis that affect other organs like liver and CNS.
  • It does not need the human intermediate to survive. Once the larvae are in the soil they develop into mature worms that produce more larvae.
  • Statistics: Size of the female worm - 2.0 to 2.5 mm; size of the male worm - 0.9 mm; affects 30-100 million people globally.
  • Life cycle

_Eggs in the stool

_Hatch into rhabditiform larvae

_Rhabditiform larvae molt into filariform larvae

_Filariform larvae penetrate human skin

_The larvae penetrate into pulmonary alveoli

_The larvae ascend the bronchial tree to the epiglottis

_The larvae are swallowed.

_The larvae develop into adults in the small intestine (2 wks to mature).

_Occassionally rhabditiform larvae convert within the intestine to filariform larvae which re-enter the bowel wall and rejoin the cycle to the lungs. This is known internal auto-infection.

_Other times filariform larvae are passed in stool and re-enter through the skin of the buttocks and thighs. This is known as external auto-infection.

Symptoms
  • Mainly asymptomatic
  • Larva curren (which is a form of cutenous larva migran that is specific for Stercoralis. In this case the multuplecreeping infections are evident mainly from anus to the rest of the body).
  • Rash
  • Diarrhea
  • Soiling of the inner wear with the stools
  • Fatigue
  • Loeffler’s syndrome (caused by migration of numerous larvae through the lungs and characterized by:

_cough

_wheezing

_eosinophilia

_hemoptysis)

  • Weight loss or retarded growth in children
  • Malnutrition
  • GI obstruction
  • GI bleeding
  • Abdominal pain
  • Rarely brain abscess, parasitic meningitis and hepatitis in case of hyperinfection, especially in an immunocompromised persons
Diagnosis
  • Microscopy for motile larva and worms in the stool
  • Immuno-Assays (for detection of worm’s antibodies)
  • Chest X-Ray (in case of suspected disseminated strongyloidiasis).
Management

Either,

Over 2 years: (children and adults): _Tabs/susp Albendazole 400mg BD x 7/7

Or;

_ Ivermectin 200 mcg/kg OD x 2/7

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