Strongyloides stercoralis and S fuelleborni Dwarf Threadworms

Causative agents of strongyloidosis

Parasites and occurrence. Strongyloides stercoralis, which parasitizes humans, dogs, and monkeys, occurs mainly in moist, warm climatic zones, and more rarely in temperate zones (e.g., southern and eastern Europe). About 50-100 million persons are infected worldwide (WHO, 1995). Stron-

gyloides fuelleborni is mainly a parasite of African monkeys, but is also found in humans.

Morphology, life cycle, and epidemiology (Fig. 10.15). Only Strongyloides females are parasitic. They are 2-3 mm long and live in the small intestine epithelium, where they produce their eggs by parthenogenesis. During the intestinal passage first-stage larvae (0.2-0.3 mm long) hatch from the eggs and are shed in stool (whereas eggs are shed in S. fuelleborni infections). Within a few days first-stage larvae develop into infective third-stage larvae.

— Strongyloides stercoralis: Life Cycle

— Strongyloides stercoralis: Life Cycle

Strongyloidosis

Fig. 10.15 1 Female Strongyloides from the small intestine; 2 first-stage larva (L1) shed in stool; 3 L2 larva; 4 infective L3 larva; 5 development of L1 larva to adult stages including four moltings (6); 6a free-living male (not host-bound); 6b free-living female; 7 egg of free-living generation; 8 larva hatched from egg, develops into infective larva including two moltings.

Fig. 10.15 1 Female Strongyloides from the small intestine; 2 first-stage larva (L1) shed in stool; 3 L2 larva; 4 infective L3 larva; 5 development of L1 larva to adult stages including four moltings (6); 6a free-living male (not host-bound); 6b free-living female; 7 egg of free-living generation; 8 larva hatched from egg, develops into infective larva including two moltings.

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  • peter wirth
    What is dwarfthread worm?
    3 years ago
  • nadine
    What do strongyloides look like?
    2 years ago

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