S.stercoralis Flashcards
(22 cards)
What are the two characterized forms of Strongyloides Stercoralis?
Free-living rhabditiform and parasitic filariform.
What is the common name for Strongyloides Stercoralis?
Threadworm.
What is the primary habitat of Strongyloides Stercoralis in humans?
Small Intestine.
What is the mode of transmission for Strongyloides Stercoralis?
Skin penetration.
What is the infective stage of Strongyloides Stercoralis?
Filariform larvae.
What is the diagnostic stage of Strongyloides Stercoralis in stool samples?
Rhabditiform larvae.
Describe the migration route of Strongyloides Stercoralis larvae in the human body after skin penetration.
Heart-lung route.
Name some common laboratory diagnostic methods for Strongyloides Stercoralis.
DFS, Concentration technique
Harada-Mori
Direct examination of sputum
Serology
What specialized culture technique is used to demonstrate rhabditiform larvae and for species identification in Strongyloides Stercoralis?
Harada-Mori culture.
How does the Harada-Mori culture work?
Allows the hatching of larvae from eggs on strips of filter paper with one end immersed in water.
Describe the morphology of Strongyloides Stercoralis males.
Shorter, broader, do not have penetrating power (do not invade the intestinal wall), presence of copulatory spicules.
Describe the morphology of Strongyloides Stercoralis females.
Small, thin, measuring 2-3mm in length and 30-50 um in width.
Describe the morphology of Strongyloides Stercoralis ova (eggs).
48 um by 35 um, thin-shelled, transparent, and oval containing larvae ready to hatch.
Compare the rhabditiform larvae and filariform larvae of Strongyloides Stercoralis based on their mouth/buccal canal.
Rhabditiform larvae: Shorter mouth/buccal canal; Filariform larvae: Possess short mouth.
Compare the rhabditiform larvae and filariform larvae of Strongyloides Stercoralis based on their esophagus.
Rhabditiform larvae: Double-bulb elongated esophagus; Filariform larvae: Long cylindrical esophagus occupying half the length of the larvae.
Which larval stage of Strongyloides Stercoralis is highly infectious?
Filariform larvae.
What is a key morphological feature of the filariform larvae’s tail?
Forked/notched tail.
How do Strongyloides Stercoralis larvae cause pulmonary lesions?
Larvae migrate through the lungs, breaking out of the pulmonary capillaries into the alveoli, causing hemorrhages.
What are some symptoms of intestinal lesions caused by Strongyloides Stercoralis?
Intermittent abdominal pain, distension, bloating, and diarrhea.
What is ‘hyperinfection’ in Strongyloides Stercoralis infection, and what underlying conditions is it often seen with?
Filariform larvae enter the arterial circulation and lodge in various organs. Seen with underlying immune defects, autoimmune disease, protein malnutrition.
Name some prophylactic measures against Strongyloides Stercoralis infection.
Proper disposal of human waste, avoidance of contact with fecally contaminated soil, treatment of all diagnosed cases.
What is a common treatment for Strongyloides Stercoralis infection?
Thiabendazole.
While Thiabendazole is mentioned, Ivermectin is often the first-line treatment in current practice.
