Helminthology - Cestodes & Trematodes MCQs

a) Lepromin test: Type 4 Hypersensitivity b) Tuberculin test: Type 4 Hypersensitivity c) Casoni's test: Type 1 Hypersensitivity d) Arthus reaction: Type 3 Hypersensitivity Examples of Type I Hypersensitivity: Experiments: P-K reaction Schultz Dale phenomenon Theobald smith phenomenon Systemic anaphylaxis Localized anaphylaxis (atopy) such as: Allergic rhinitis (or hay fever) Asthma Food allergy Atopic urticarial Atopic dermatitis (allergic eczema) Drug allergy Wheal and flare reaction. Parasitic diseases: Tropical Pulmonary Eosinophilia (TPE) Loeffler's pneumonia (Ascaris) Ground itch (Hookworm) Leakage of hydatid fluid Cercarial dermatitis/swimmer's itch (Schistosoma). Parasitic tests: Casoni test (hydatid disease) Reference: Ananthanarayan and Paniker's Textbook of Microbiology 10th edition Chapter 16, Pg 164-168

Enterotest is a simple method of obtaining duodenal contents. Patient is allowed to swallow a gelatin capsule in which a thread of nylon yarn is coiled. The end of the yarn is affixed to the patient's face. Upon reaching the stomach, gelatin dissolves and a weighted string is carried to duodenum. Secretions are retrieved after 3-4 hours and content adhered to yarn is scraped off and examined under microscope. Traditionally used for Giardia lamblia, it is now used to collect eggs of F.hepatica, larva of S.stercoralis and oocyst of Isospora. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. -35

Option B - S.mansoni resides in venules of inferior mesenteric vein in sigmoido-rectal region. Because of the presence of characteristic eggs having lateral spine, eggs deposited in the intestinal wall leads to erosion, microabscesses, granuloma and dysentry. Reference: Paniker's textbook of Parasitology - 8th Edition, Pg. No. 148

Clonorchis sinensis is called Chinese liver fluke. Morphology:- Adult worm-lives in biliary tract and sometimes in pancreatic duct. Eggs-eggs are flask shaped and operculated. Mode of infection-By eating undercooked freshwater fish carrying metacercariae larva. Chronic infection has also been linked to cholangiocarcinoma. Reference : Ananthnarayan and Paniker's textbook of Microbiology 12 th edition pg no.536

Option B – Auto infection is a feature of Taenia solium but not of Taenia saginata. Due to unhygienic habits of not washing hands, a person having taeniasis due to T.solium can auto infect himself resulting in cysticercosis. Option A – In H.nana, internal and external autoinfection takes place. Internal infection is due to eggs in the intestine hatch, penetrate mucosa and develop into larval stage (cysticercoid). External autoinfection is due to faeco-oral contamination due to unhygienic habits. Option B – E.vermicularis has features of auto infection and retro infection. Option C – S.stercoralis can undergo auto infection (hyper infection syndrome) in persons with defective cellular immune response. Reference : Paniker’s textbook of Parasitology - 8th Edition, Pg. No. 137,183, 196

Hydatid disease is caused by Echinococcus granulosus Definitive host-Dog Intermediate host and accidental host-MAN Waterlily sign is seen in ultrasound. This is due to collapsed cyst (floating membrane)floating in the abdomen. Reference: Essentials of medical Parasitology by Apurba sastry 2nd edition Pg no.181

This is seen in chronic schistosomiasis, due to fibrosis and granuloma formation as a result of egg deposition in sites like liver which is called symmers pipestem fibrosis. Reference : Essentials of medical Parasitology by Apurba sastry 2nd edition Pg no.200

Neurocysticercosus is caused by eating pork. Option C - Antigen can be detected in CSF and serum by ELISA using monoclonal antibodies and indicate recent infection. Anticysticercus antibodies can be detected in CSF or serum by ELISA. Surgical excision is the best treatment wherever possible. Albendazole or praziquantel along with corticosteroids can be given. Reference: Paniker's textbook of Parasitology - 8th Edition, Pg. No. 126-27