36 Questions
What is the complexity of helminths?
Multi-cellular
Which immune cells are elevated in response to helminth infections?
Eosinophils
What are the diagnostic forms for helminth infections?
Eggs / Larvae
Which parasite is classified under Cestodes?
$Taenia saginata$
When do the symptoms of helminth infections typically onset?
>1 month
Which parasite is known to cause nocturnal pruritus ani and anal itching?
Enterobius Vermicularis (Oxyuris)
Which parasite is located in the lumen of the cecum and can lead to rectal prolapse in children with heavy infection?
Trichuris trichiura
Which parasite requires its eggs to be in the soil for 3 weeks to reach the infective stage?
Ascaris Lumbricoides
Which parasite causes iron-deficiency anemia and protein deficiency through walking barefoot in areas contaminated with fecal matter?
Ancylostoma duodenale & Necator americanus
Which parasite is fatal in immunocompromised hosts and can cause internal and external autoinfection?
Strongyloides Stercoralis
Which type of parasite is Enterobius vermicularis?
Roundworm (Nematode)
What is the primary mode of transmission for Enterobius vermicularis?
Fecal-oral route
Which of the following symptoms are associated with Enterobius vermicularis infection?
Anal itching and nocturnal pruritus ani
What is the size range of Nematodes?
$<$ 1 cm to about 100 cm
What are the three main classifications of Helminths based on their morphology?
Roundworms (Nematodes), Flatworms (Trematodes), Tapeworms (Cestodes)
What is the treatment for T. saginata infection?
Praziquantel
How are humans infected by E. granulosus?
Ingesting eggs through hand-to-mouth contact with contaminated dog feces
What is the definitive host for E. granulosus?
Dogs
How is cysticercosis caused by Hymenolepis nana contracted?
Through ingestion of eggs
Where do the larvae of Hookworms enter the human body?
Through the skin
Which nematode infection is characterized by the presence of un-embryonated eggs in stool?
Trichuris Trichiura
Which nematode infection can lead to emotional disturbance, loss of weight, insomnia, and loss of concentration in infected children?
Ascaris Lumbricoides
Which nematode infection is commonly found in the small intestine, especially in the jejunum and upper part of the ileum?
Ascaris Lumbricoides
Which nematode infection can lead to intestinal obstruction, heavy infection, and migration to the bile duct causing jaundice?
Ascaris Lumbricoides
Which nematode infection is transmitted through the fecal-oral route and can cause cutaneous larva migrans (creeping eruption)?
Strongyloides Stercoralis
Which nematode is the smallest pathogenic nematode?
Strongyloides stercoralis
In which human body location do adult Taenia saginata primarily reside?
Small intestine
What is the infective stage of Taenia solium (pork tapeworm) acquired by ingesting undercooked pork?
Cysticerci
Which mode of development involves rhabditiform larvae becoming free-living adults in the soil and producing eggs?
Indirect or external development
What is a characteristic clinical symptom of Enterobius vermicularis infection?
Rectal prolapse in children
Which helminth infection is characterized by heavy infection with adult worms causing intestinal obstruction and infection with larvae causing loeffer’s syndrome?
Ascaris lumbricoides
Which helminth is primarily located in the lumen of the cecum and can lead to rectal prolapse in children with heavy infection?
Trichuris trichiura
Which helminth infection is transmitted through walking barefoot through areas contaminated with fecal matter and gives rise to iron-deficiency anemia & protein deficiency?
Ancylostoma duodenale & Necator americanus
Which helminth infection is diagnosed by the cellulose adhesive test and causes nocturnal pruritus ani and anal itching?
Enterobius vermicularis
Which helminth infection can lead to internal and external autoinfection, mainly in immunocompromised patients, and is fatal in such hosts?
Strongyloides stercoralis
Which helminth infection has eggs that need to be in the soil for 3 weeks to reach the infective stage?
Ascaris lumbricoides
Study Notes
○ Strongyloidiasis is a serious infection caused by the nematode Strongyloides stercoralis, which can be fatal in immunocompromised hosts. ○ The parasite is the smallest pathogenic nematode, measuring less than 2.5mm. ○ Adult worms live in the mucous membrane of the duodenum and jejunum, rarely in the mucous membrane of the bronchus. ○ The parasite has three modes of development: 1) Direct development, where rhabditiform larvae become filariform larvae in the intestinal mucosa or perianal area and penetrate the intestine; 2) Indirect or external development, where rhabditiform larvae become free-living adults in the soil and produce eggs, which hatch into rhabditiform larvae and filariform larvae (infective stage) that penetrate the skin; 3) Autoinfection, mainly in immunocompromised patients. ○ The clinical picture of strongyloidiasis includes: 1) Cutaneous: little reaction on penetration, severe dermatitis at the perianal region in case of external autoinfection; 2) Migration: pneumonitis during larval migration; 3) Intestinal: inflammation of the upper intestinal mucosa, diarrhea, upper abdominal pain; 4) Disseminated strongyloidiasis: uncontrolled diarrhea, granulomatous changes, necrosis, perforation, peritonitis, and death. ○ Diagnostic stages for strongyloidiasis include the presence of rhabditiform larvae in the soil, stool examination, duodenal aspiration, and the detection of adult worms in the stool or anus. ○ The parasite is the only one to exit the soil as diagnostic rhabditiform larvae. ○ Common intestinal nematodes include Enterobius vermicularis, Ascaris lumbricoides, Trichuris trichiura, Hookworm, Ancylostoma duodenale & necator americanus, and Strongyloides stercoralis. ○ Characteristics of common intestinal nematodes include: location in the adult human body, diagnostic stage, and symptoms. ○ The clinical picture for Enterobius vermicularis includes itching and pruritus at the site of entry, cough and blood in the sputum during larval migration, and rectal prolapse in children. ○ Cestodes worms are tape-like segmented parasites that can continue to live if cut in the middle. ○ Taenia saginata (beef tapeworm) has a life cycle involving cattle as the intermediate host and humans as the definitive host. The infective stage is the cyst, which can be acquired by eating undercooked beef. ○ Taenia solium (pork tapeworm) can infect humans by eating eggs or undercooked pork containing cysticerci. The clinical picture includes cysticercosis in various parts of the body, with cysts in the brain, eyes, and skin being particularly dangerous. The infective stage is the cyst, which is acquired by ingesting undercooked pork. ○ The clinical diagnosis of Taenia solium involves finding typical segments (proglottids) and eggs in the feces, as well as a CT scan of the brain or abdomen to locate the cysticerci in the human body. ○ The majority of cases with adult Taenia saginata in the small intestine are asymptomatic, but some may experience vague intestinal discomfort, vomiting, diarrhea, malaise, and abdominal cramps.
Test your knowledge of Strongyloides stercoralis, a potentially fatal nematode parasite that affects immunocompromised individuals. Explore its life cycle, modes of development, and the impact of autoinfection. This quiz will challenge your understanding of this dangerous parasite.
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