Strongyloidiasis

Question 1

Which strain causes Strongyloidiasis?

Answer 1

Strongyloides stercoralis

Question 2

What is the global distribution of Strongyloides stercoralis?

Answer 2

Worldwide

Question 3

What is the life cycle of Strongyloides stercoralis?

Answer 3

Free-living adults copulate and lay eggs in the soil
Rhabditiform juveniles transform into filariform juveniles and penetrates the skin
Juveniles enter lymphatics or bloodstream and pass through heart into lungs
They pass up trachea and into esophagus and then intestine
Adult female develops in intestine and hatch eggs
Rhabditiform juveniles released and passed in feces

Question 4

What is the heterogonic cycle?

Answer 4

Rhabditiform juveniles shed 4 times before becoming full adults

Question 5

What is the homogonic cycle?

Answer 5

Juveniles passed in feces shed 2x before becoming filariform juveniles

Question 6

How does autoinfection occur?

Answer 6

Rhabditiform juveniles penetrate mucosa after 2 molts and enter the bloodstream or lymphatics

Question 7

What is a feature of the rhabditiform esophagus?

Answer 7

Prominent bulb

Question 8

What are the major hosts of Strongyloides stercoralis?

Answer 8

Humans, primates, dogs, cats

Question 9

True or false: Parasitic adults are sexual and free-living adults are parthenogenetic

Answer 9

False, parasitic adults are parthenogenetic and free-living adults are sexual

Question 10

At what larval stage are life history decisions made?

Answer 10

L1

Question 11

At what stage does autoinfection occur?

Answer 11

L3

Question 12

What are some known triggers of autoinfection?

Answer 12

Corticosteroids, immunosuppression, neonatal infections, infections with transplanted adults, co-infection with Th1 inducing pathogens