Tissue Nematodes — MCQs
In a patient presented with a fever and a positive filarial antigen test, what is the next appropriate method of management?
River blindness is caused by?
All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
Tropical pulmonary eosinophilia is most characteristically seen due to which of the following infections?
Which of the following parasite infections predispose to malignancies? (Select all that apply)
Which of the following statements best describes the operational definition of onchocerciasis elimination?
A 5-year-old child presented with fever, fatigue, abdominal pain, and vomiting. On further history evaluation, he had a habit of eating dog feces. Investigations show visceral larva migrans. Which animal is the most likely source of this infection in this child?
The following organism is called:
Which of the following statements about Helminths is false?
A 35 year old man presented with dry cough and rusty colored sputum. He has a history of eating in a Chinese restaurant very often with consumption of crabs. What is the probable causative agent in this condition?
Tissue Nematodes Indian Medical PG Practice Questions and MCQs
Question 1: In a patient presented with a fever and a positive filarial antigen test, what is the next appropriate method of management?
- A. Bone marrow biopsy
- B. DEC provocation test
- C. Detection of microfilariae in the blood smear (Correct Answer)
- D. Ultrasound of the scrotum
Explanation: ***Detection of microfilariae in the blood smear*** - A positive **filarial antigen test** indicates the presence of adult worms, and the next step is to confirm active infection by identifying **microfilariae**. [1] - **Nocturnal blood samples** are crucial because microfilariae of *Wuchereria bancrofti* and *Brugia malayi* exhibit **nocturnal periodicity**, meaning they are most abundant in peripheral blood between 10 PM and 2 AM. [1] *Bone marrow biopsy* - This procedure is typically used to diagnose **hematological disorders**, such as leukemia or lymphoma, or investigate causes of unexplained fever, but it is not indicated for filariasis. - While filariasis can rarely lead to **eosinophilia**, a bone marrow biopsy is not a diagnostic tool for filarial infection itself. *DEC provocation test* - The **diethylcarbamazine (DEC) provocation test** is used to bring out microfilariae into the peripheral blood during the daytime for species that exhibit nocturnal periodicity. [1] - However, it carries a risk of severe adverse reactions due to rapid killing of microfilariae, especially in cases of heavy infection, and is generally avoided when antigen tests are positive. [1] *Ultrasound of the scrotum* - Scrotal ultrasound can detect the characteristic "filarial dance sign" (motile adult worms) in the **lymphatic vessels of the scrotum and epididymis**, confirming lymphatic filariasis. [2] - While useful for assessing advanced disease manifestations like **hydrocele**, it does not quantify microfilaremia or replace the need for microscopic confirmation of circulating microfilariae to guide treatment.
Question 2: River blindness is caused by?
- A. Loa loa
- B. Ascaris
- C. B. malayi
- D. Onchocerca volvulus (Correct Answer)
Explanation: ***Onchocerca volvulus*** - **River blindness**, or **onchocerciasis**, is caused by the parasitic nematode *Onchocerca volvulus*. - This parasite is transmitted by the bite of infected **blackflies** (genus *Simulium*), which breed in fast-flowing rivers. *Loa loa* - *Loa loa* causes **Loiasis**, also known as African eye worm disease. - While it can manifest as an eye worm and cause itching and swelling, it does not typically lead to permanent blindness or the widespread skin lesions associated with river blindness. *Ascaris* - *Ascaris lumbricoides* causes **ascariasis**, an intestinal infection. - Symptoms are primarily gastrointestinal, such as abdominal pain, malnutrition, and, in severe cases, intestinal obstruction; it does not affect the eyes or cause blindness. *B. malayi* - *Brugia malayi* is one of the causes of **lymphatic filariasis**, also known as **elephantiasis**. - This disease primarily affects the lymphatic system, causing severe swelling in the limbs and genitals, but it does not cause blindness.
Question 3: All of the following conditions are immediate priorities in the WHO's "Vision -2020: The Right to sight" except:
- A. Cataract
- B. Epidemic conjunctivitis (Correct Answer)
- C. Onchocerciasis
- D. Trachoma
Explanation: ***Epidemic conjunctivitis*** - While **epidemic conjunctivitis** can cause significant discomfort and temporary vision impairment, it is generally **self-limiting** and rarely leads to permanent blindness. - It was not identified as one of the top five global causes of avoidable blindness targeted by the Vision 2020 initiative. *Cataract* - **Cataract** is the **leading cause of blindness** globally, accounting for approximately half of all cases. - It is a highly treatable condition through surgery, making it a critical priority for Vision 2020. *Onchocerciasis* - Also known as **river blindness**, onchocerciasis is a parasitic disease that causes severe visual impairment and blindness. - It is a significant public health problem in several regions, particularly in Africa, and was a key focus of Vision 2020 due to its widespread impact and the availability of preventive chemotherapy. *Trachoma* - **Trachoma** is the **leading infectious cause of blindness** worldwide, caused by *Chlamydia trachomatis*. - Given its preventable and treatable nature, and its prevalence in many impoverished areas, it was designated as one of the priority diseases under Vision 2020.
Question 4: Tropical pulmonary eosinophilia is most characteristically seen due to which of the following infections?
- A. Roundworm
- B. Trichinella
- C. Ancylostoma
- D. Filaria (Correct Answer)
Explanation: *Filaria* - **Tropical pulmonary eosinophilia (TPE)** is a hypersensitivity reaction to microfilariae from filarial nematodes like *Wuchereria bancrofti* and *Brugia malayi* [1]. - It is characterized by cough, dyspnea, wheezing, and marked **peripheral eosinophilia**, with interstitial infiltrates on chest X-ray [1]. *Roundworm* - **Ascaris lumbricoides** can cause **Loeffler's syndrome**, a transient pulmonary infiltration with eosinophilia during larval migration, but not chronic TPE [2]. - Symptoms are usually less severe and self-limiting compared to TPE [2]. *Trichinella* - **Trichinella spiralis** causes **trichinellosis**, presenting with muscle pain, fever, and periorbital edema, possibly with eosinophilia, but typically does not manifest as TPE. - Pulmonary involvement is rare and not the characteristic feature. *Ancylostoma* - **Hookworm (Ancylostoma duodenale, Necator americanus)** larvae can cause mild pulmonary symptoms and eosinophilia during migration through the lungs [3]. - However, they also do not typically lead to the severe and chronic pulmonary symptoms seen in TPE [3].
Question 5: Which of the following parasite infections predispose to malignancies? (Select all that apply)
- A. Clonorchiasis
- B. Guinea worm infection
- C. Paragonimus westermani
- D. Schistosomiasis (Correct Answer)
Explanation: Schistosomiasis - Chronic infection with *Schistosoma haematobium* is a major risk factor for developing **squamous cell carcinoma of the bladder**. [1] - The parasite's eggs deposited in the bladder wall induce chronic inflammation, cell proliferation, and ultimately **neoplastic transformation**. *Clonorchiasis* - Caused by *Clonorchis sinensis* (the Chinese liver fluke), which is strongly associated with **cholangiocarcinoma** (bile duct cancer). - Chronic inflammation and mechanical irritation from the flukes in the bile ducts lead to epithelial hyperplasia and, eventually, malignant changes. *Guinea worm infection* - Caused by *Dracunculus medinensis*, which primarily causes painful skin lesions and ulcers as the adult worm emerges. - While it causes significant morbidity, there is **no known association** with an increased risk of malignancy. *Paragonimus westermani* - This lung fluke causes paragonimiasis, leading to chronic inflammation and granuloma formation in the lungs, mimicking tuberculosis. - Although it causes severe pathology, there is **no well-established link** between *Paragonimus westermani* infection and the development of malignancy.
Question 6: Which of the following statements best describes the operational definition of onchocerciasis elimination?
- A. All interventions have been successfully implemented.
- B. There is no recrudescence of the disease after a defined period.
- C. All of the options are true.
- D. Transmission of O. volvulus has been reduced to a level where it cannot sustain itself in the population. (Correct Answer)
Explanation: **Transmission of O. volvulus has been reduced to a level where it cannot sustain itself in the population.** - This statement accurately reflects the definition of **disease elimination**, where the incidence of infection is reduced to zero in a defined geographical area, signifying that the **transmission cycle can no longer be sustained**. - For onchocerciasis, this means the **vector (blackfly)** is no longer transmitting the parasite (*Onchocerca volvulus*) between humans at a rate that allows the disease to persist. *All interventions have been successfully implemented.* - While successful implementation of interventions is crucial for elimination, it is a **process goal**, not the **ultimate outcome** or operational definition of elimination itself. - Elimination is defined by the **absence of sustained transmission**, which is a direct measure of disease burden, not intervention fidelity. *There is no recrudescence of the disease after a defined period.* - The **absence of recrudescence** (re-emergence) after a defined period is an important indicator of successful elimination validation, but it is a **consequence** or **part of the verification process**, not the primary operational definition. - The operational definition focuses on the **state of transmission** that leads to this sustained absence. *All of the options are true.* - This option is incorrect because only one of the provided statements accurately describes the **operational definition of elimination** in the context of parasitic diseases like onchocerciasis. - The other options describe aspects related to the elimination process or its verification, but not the core definition.
Question 7: A 5-year-old child presented with fever, fatigue, abdominal pain, and vomiting. On further history evaluation, he had a habit of eating dog feces. Investigations show visceral larva migrans. Which animal is the most likely source of this infection in this child?
- A. Pig
- B. Monkeys
- C. Cows
- D. Dogs (Correct Answer)
Explanation: ***Dogs*** - The history of eating **dog feces** directly links to the transmission of **Toxocara canis** eggs, the primary cause of visceral larva migrans. - Humans, especially children, can get infected by ingesting infective eggs from contaminated soil or dog feces. *Pig* - While pigs can harbor parasites like **Taenia solium** (pork tapeworm) and **Trichinella spiralis**, these do not typically cause visceral larva migrans. - Transmission from pigs usually involves consumption of undercooked pork, not direct contact with feces in the context of visceral larva migrans. *Monkeys* - Monkeys are not a common source of parasites causing human visceral larva migrans. - Parasitic infections associated with monkeys in humans are generally rare and usually specific to certain geographical contexts or exotic pet exposure. *Cows* - Cows can be hosts for parasites such as **Taenia saginata** (beef tapeworm), but they are not associated with visceral larva migrans caused by *Toxocara* species. - Ingestion of raw or undercooked beef is the typical mode of transmission for cow-related parasitic infections.
Question 8: The following organism is called:
- A. Cestode (Correct Answer)
- B. Nematode
- C. Trematode
- D. Annelid
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.
Question 9: 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
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.
Question 10: A 35 year old man presented with dry cough and rusty colored sputum. He has a history of eating in a Chinese restaurant very often with consumption of crabs. What is the probable causative agent in this condition?
- A. Pneumocystis jirovecii
- B. Paragonimus westermani (Correct Answer)
- C. Strongyloides stercoralis
- D. Diphyllobothrium latum
Explanation: ***Paragonimus westermani*** - The key clinical features are **dry cough**, **rusty-colored sputum**, and a history of consuming **crabs**. These are classic indicators of **paragonimiasis**. - *Paragonimus westermani* is a **lung fluke** acquired by eating undercooked freshwater crabs or crayfish. *Pneumocystis jirovecii* - This fungus typically causes pneumonia in **immunocompromised individuals**, like those with HIV/AIDS. - While it can cause a dry cough, **rusty-colored sputum** is not a characteristic sign, and there's no mention of immunocompromise. *Strongyloides stercoralis* - This parasite primarily causes **gastrointestinal symptoms** (e.g., abdominal pain, diarrhea) and can lead to cutaneous manifestations (larva currens). - While lung involvement can occur in severe cases (hyperinfection), it does not typically present with **rusty sputum** or a direct association with crab consumption. *Diphyllobothrium latum* - This is the **fish tapeworm**, acquired by eating undercooked freshwater fish. - It primarily causes **gastrointestinal symptoms** such as abdominal pain and diarrhea, and is known for causing **vitamin B12 deficiency** leading to megaloblastic anemia, not pulmonary symptoms.
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