Intestinal Helminths: Nematodes Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Intestinal Helminths: Nematodes. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Intestinal Helminths: Nematodes Indian Medical PG Question 1: Drug of choice for mass therapy under filariasis control programme?
- A. Albendazole
- B. Ivermectin
- C. DEC (Correct Answer)
- D. Mebendazole
Intestinal Helminths: Nematodes Explanation: ***Correct: DEC***
- **Diethylcarbamazine (DEC)** is the drug of choice for **mass drug administration (MDA)** campaigns aimed at eliminating lymphatic filariasis.
- It effectively kills **microfilariae** and has some action on adult worms, reducing transmission.
- In India's National Filariasis Elimination Programme, DEC is administered along with Albendazole in annual MDA campaigns.
*Incorrect: Albendazole*
- While **Albendazole** is co-administered with DEC in MDA programs, it is not the sole drug of choice for mass treatment of filariasis.
- Its primary role is to provide **macrofilaricidal** activity (killing adult worms) and co-treatment for other helminth infections.
- It enhances the effect of DEC but is not used alone.
*Incorrect: Ivermectin*
- **Ivermectin** is used in MDA programs for filariasis, particularly in areas co-endemic with **onchocerciasis** or where **Loa loa** is prevalent (as DEC is contraindicated in these areas).
- However, in India and most lymphatic filariasis endemic areas, **DEC** remains the primary drug.
*Incorrect: Mebendazole*
- **Mebendazole** is an anthelminthic primarily used for treating **intestinal nematode infections** like ascariasis, trichuriasis, and hookworm.
- It is **not used** in lymphatic filariasis mass treatment programs.
Intestinal Helminths: Nematodes Indian Medical PG Question 2: Which larvae infect humans by penetrating through the skin?
- A. Ancylostoma duodenale (Correct Answer)
- B. Ascaris lumbricoides
- C. Trichinella spiralis
- D. Enterobius vermicularis
Intestinal Helminths: Nematodes Explanation: ***Ancylostoma duodenale***
- The **filariform larvae** (L3) of *Ancylostoma duodenale*, a **hookworm**, are capable of penetrating intact **human skin**, typically through the feet.
- This penetration is how the infection initially establishes in the host, leading to a migratory phase through the circulatory and respiratory systems.
*Ascaris lumbricoides*
- Humans become infected with *Ascaris lumbricoides* by ingesting **embryonated eggs**, usually through contaminated food or water.
- The larvae hatch in the small intestine and then embark on a **lung migration phase**, but they do not penetrate the skin to initiate infection.
*Trichinella spiralis*
- Infection with *Trichinella spiralis* occurs by consuming undercooked meat, particularly **pork**, containing infectious cysts.
- The larvae are released in the stomach and small intestine, then migrate throughout the body to encyst in muscle tissue, without a skin penetration stage.
*Enterobius vermicularis*
- Humans acquire *Enterobius vermicularis* (pinworm) infection by ingesting the **embryonated eggs**, often through **self-ingestion** due to perianal itching or contact with contaminated surfaces.
- The life cycle is direct and does not involve larval penetration of the skin.
Intestinal Helminths: Nematodes Indian Medical PG Question 3: Which of the following is not helpful in preventing dracunculiasis?
- A. Filtering of drinking water
- B. Education regarding water hygiene
- C. Active search for new cases
- D. Mass mebendazole treatment (Correct Answer)
Intestinal Helminths: Nematodes Explanation: ***Mass mebendazole treatment***
- Dracunculiasis (guinea worm disease) is caused by the nematode *Dracunculus medinensis*, which is transmitted through contaminated water containing copepods (water fleas) infested with larvae. **Mebendazole** is an anthelmintic medication effective against intestinal worms but has no known efficacy against *Dracunculus medinensis*.
- This treatment strategy would be **ineffective** in breaking the life cycle of the guinea worm or preventing infection.
*Filtering of drinking water*
- This is a highly effective method as it removes the **copepods** (water fleas) containing the *Dracunculus medinensis* larvae from drinking water, thus preventing ingestion and infection.
- Providing **cloth filters** or teaching filtration techniques is a cornerstone of dracunculiasis eradication programs.
*Education regarding water hygiene*
- Educating communities about the transmission of the disease through contaminated water and the importance of only drinking safe water is crucial for behavioral change and prevention.
- This includes advising against entering water sources when infected to prevent adult worms from releasing larvae, thereby interrupting the **transmission cycle**.
*Active search for new cases*
- Identifying and isolating individuals with emerging guinea worms allows for proper wound care and prevents them from re-contaminating water sources with new larvae.
- This strategy, combined with **containment measures** for infected individuals, is vital for monitoring and interrupting disease transmission in endemic areas.
Intestinal Helminths: Nematodes Indian Medical PG Question 4: Which of the following parasitic infections is characteristically associated with colitis?
- A. Strongyloides
- B. Clonorchis
- C. Enterobius vermicularis
- D. Trichuris trichiura (Correct Answer)
Intestinal Helminths: Nematodes Explanation: ***Trichuris trichiura***
- Also known as **whipworm**, *Trichuris trichiura* primarily infects the **large intestine**, particularly the cecum and ascending colon.
- Heavy infections can lead to **colitis**, characterized by bloody diarrhea, abdominal pain, and rectal prolapse in severe cases.
*Strongyloides*
- *Strongyloides stercoralis* infection (strongyloidiasis) primarily affects the **small intestine** and can cause symptoms like abdominal pain, diarrhea, and malabsorption.
- While it can lead to gastrointestinal symptoms, it is not typically associated with prominent **colitis** as its primary manifestation.
*Clonorchis*
- *Clonorchis sinensis* (Chinese liver fluke) infects the **biliary ducts** of the liver, causing **cholangitis** and potentially cholangiocarcinoma.
- It does not primarily cause **colitis** or involve the large intestine.
*Enterobius vermicularis*
- *Enterobius vermicularis* (pinworm) primarily resides in the **cecum and appendix**, causing perianal itching, especially at night.
- While it can cause some localized irritation, it does not typically lead to **colitis** or significant inflammation of the large intestine.
Intestinal Helminths: Nematodes Indian Medical PG Question 5: Which of the following statements about Helminths is false?
- A. Alimentary canal is complete in Nematodes
- B. Nematodes have separate sexes
- C. Body cavity is present in trematodes (Correct Answer)
- D. Alimentary canal is present but incomplete in trematodes
Intestinal Helminths: Nematodes Explanation: ***Body cavity is present in trematodes***
- Trematodes are **flatworms** (Platyhelminthes), which are **acoelomate**, meaning they lack a true body cavity or coelom.
- Their internal organs are embedded in a **parenchymal tissue** rather than being suspended within a fluid-filled cavity.
*Alimentary canal is complete in Nematodes*
- **Nematodes** (roundworms) possess a **complete alimentary canal**, with a distinct mouth, intestine, and anus.
- This allows for **unidirectional flow of food** and waste through their digestive system.
*Nematodes have separate sexes*
- **Nematodes** are generally **dioecious**, meaning they have separate male and female individuals.
- This sexual dimorphism is a characteristic feature for most species within this phylum.
*Alimentary canal is Present but incomplete*
- The statement refers to the digestive system of **Platyhelminthes** (flatworms) like trematodes and cestodes, where the alimentary canal is present but **incomplete** (lacking an anus).
- This means they have a **single opening** that serves as both mouth and anus for digestion.
Intestinal Helminths: Nematodes Indian Medical PG Question 6: Meyers Kouwenaar syndrome is a synonym for ?
- A. Occult filariasis (Correct Answer)
- B. Larva migrans
- C. Tropical pulmonary eosinophilia
- D. Cutaneous allergic reactions to Ascariasis
Intestinal Helminths: Nematodes Explanation: ***Occult filariasis***
- **Meyers Kouwenaar syndrome** is a historical term used to describe **occult filariasis**, particularly those cases involving the lymphatics without the presence of microfilariae in peripheral blood.
- This syndrome is characterized by **chronic lymphatic obstruction** and **eosinophilia**, often due to an immunological response to filarial antigens.
*Larva migrans*
- **Larva migrans** refers to conditions (cutaneous or visceral) caused by the migration of **nematode larvae** in human tissues.
- It describes the migratory phase of the parasite and is not a synonym for occult filariasis, which is a specific clinical manifestation of filarial infection.
*Tropical pulmonary eosinophilia*
- **Tropical pulmonary eosinophilia (TPE)** is a distinct clinical syndrome characterized by **nocturnal cough**, **dyspnea**, and **marked peripheral eosinophilia**, caused by an allergic reaction to Wuchereria bancrofti or Brugia malayi microfilariae that are trapped in the lungs.
- While it is a form of occult filariasis (microfilariae are absent in the blood), it is a specific presentation and not a general synonym for Meyers Kouwenaar syndrome, which typically refers to lymphatic involvement.
*Cutaneous allergic reactions to Ascariasis*
- **Cutaneous allergic reactions to Ascariasis** typically involve manifestations like **urticaria** or **angioedema** due to migration of Ascaris larvae or exposure to adult worms.
- This is a reaction to a different parasitic infection (Ascaris lumbricoides) and does not relate to filariasis.
Intestinal Helminths: Nematodes Indian Medical PG Question 7: The following organism is called:
- A. Cestode (Correct Answer)
- B. Nematode
- C. Trematode
- D. Annelid
Intestinal Helminths: Nematodes Explanation: ***Cestode***
- The image displays a long, **segmented, ribbon-like worm**, which is characteristic morphology of a **tapeworm (cestode)**.
- Cestodes typically possess a head (scolex) for attachment and a body composed of repeating segments called **proglottids**.
*Nematode*
- **Nematodes** are generally **unsegmented**, cylindrical, and elongated worms, often described as roundworms.
- They lack the distinct proglottids and flattened, ribbon-like appearance seen in the image.
*Trematode*
- **Trematodes**, also known as flukes, are typically **leaf-shaped** and **unsegmented**.
- They are much broader and flatter than the organism shown, and do not have the visible segmentation.
*Annelid*
- **Annelids** are segmented worms like earthworms and leeches, but they have a **cylindrical body** with visible external ring-like segments.
- Unlike cestodes, annelids have a complete digestive system and lack the flat, ribbon-like morphology and internal proglottid structure characteristic of tapeworms.
Intestinal Helminths: Nematodes Indian Medical PG Question 8: Flask-shaped ulcers in the intestine are caused by which of the following?
- A. TB
- B. Giardia
- C. Entamoeba histolytica (Correct Answer)
- D. Typhoid
Intestinal Helminths: Nematodes Explanation: ***Entamoeba histolytica***
- *Entamoeba histolytica* is a protozoan that causes **amoebiasis**, which is characterized by **flask-shaped (bottle-shaped) ulcers** in the colon - this is the **pathognomonic feature** of intestinal amoebiasis.
- The trophozoites invade the intestinal mucosa and submucosa, creating a **narrow neck at the mucosal surface** and a **wider base in the submucosa**, giving them their unique flask-like appearance.
- These ulcers are most commonly found in the **cecum and ascending colon**.
*TB*
- Intestinal tuberculosis typically causes **transverse ulcers** (perpendicular to the bowel axis) due to lymphatic spread and caseous necrosis, often in the ileocecal region.
- These ulcers are usually associated with **granulomas** and acid-fast bacilli, which are histologically distinct from flask-shaped ulcers.
*Giardia*
- *Giardia lamblia* (or *intestinalis*) is a flagellate that causes **giardiasis**, primarily adhering to the small intestinal villi and causing malabsorption and diarrhea.
- It is **non-invasive** and does not penetrate the intestinal wall or cause ulcer formation; its pathology is mainly due to **mucosal inflammation** and villous blunting.
*Typhoid*
- Typhoid fever, caused by *Salmonella Typhi*, commonly leads to **longitudinal ulcers** (parallel to the bowel axis) in the **Peyer's patches** of the ileum due to bacterial invasion and necrosis of lymphoid tissue.
- These ulcers may perforate but do not present with the flask-shaped morphology characteristic of amoebiasis.
Intestinal Helminths: Nematodes Indian Medical PG Question 9: A 35 year old HIV positive patient comes with intractable diarrhea, crampy, abdominal pain and vomiting. Biopsy of small intestine was taken which shows cyst < 10 µm as given below. What is the appropriate diagnosis?
- A. Giardia lamblia
- B. Isospora belli
- C. Cryptosporidium parvum (Correct Answer)
- D. CMV
Intestinal Helminths: Nematodes Explanation: ***Cryptosporidium parvum***
- This parasite causes **chronic, severe watery diarrhea** in immunocompromised patients, particularly those with **HIV/AIDS**, fitting the clinical picture of intractable diarrhea.
- The biopsy showing **small cysts (<10 µm)** attached to the enterocytes in the small intestine is characteristic of *Cryptosporidium parvum*.
*Giardia lamblia*
- *Giardia lamblia* typically presents with **malabsorption** and **greasy stools**; while it can cause chronic diarrhea, the characteristic small cysts on biopsy in an HIV patient are more indicative of cryptosporidiosis.
- Its cysts are usually larger (8-12 µm) and trophozoites are pear-shaped, differing from the morphology shown.
*Isospora belli*
- *Isospora belli* causes diarrhea in immunocompromised patients but its oocysts are **larger (20-30 µm)** and typically **ellipsoidal**, which contradicts the <10 µm cyst size mentioned.
- Diagnosis is often made by identifying oocysts in stool samples, and while it infects the small intestine, the biopsy finding is less typical for *Isospora belli*.
*CMV*
- **Cytomegalovirus (CMV)** colititis or enteritis in HIV patients typically causes **ulcerations** and **inflammation** often with characteristic **owl's eye inclusions** in infected cells on biopsy, not small cysts.
- While CMV can cause diarrhea and abdominal pain, the specified biopsy finding of small cysts points away from a viral etiology like CMV.
Intestinal Helminths: Nematodes Indian Medical PG Question 10: Largest intestinal protozoan is?
- A. E. coli
- B. Balantidium coli (Correct Answer)
- C. Giardia
- D. T. gondii
Intestinal Helminths: Nematodes Explanation: ***Balantidium coli***
- *Balantidium coli* is the **largest protozoan parasite** known to infect humans, specifically found in the intestines.
- It causes **balantidiasis**, an intestinal infection, and is notable for its ciliated trophozoite stage.
*E. coli*
- *E. coli* is a **bacterium**, not a protozoan.
- While it is a common inhabitant of the intestines, it is significantly smaller than parasitic protozoa.
*Giardia*
- *Giardia lamblia* (or *intestinalis*) is a **flagellate protozoan** that causes giardiasis.
- Though an intestinal parasite, it is considerably smaller than *Balantidium coli*.
*T. gondii*
- *Toxoplasma gondii* is an **intracellular protozoan parasite** known for causing toxoplasmosis.
- It is much smaller than *Balantidium coli* and primarily infects cells, not existing as a large free-living form in the intestine.
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