Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 161: In tuberculosis the cytokine causing fever is

A. IL-1 (Correct Answer)
B. IL-2
C. IL-3
D. IL-4

Explanation: ***ILI*** - **IL-1** plays a crucial role in the inflammatory response to tuberculosis, leading to symptoms such as **fever** and **malaise**. - It is primarily produced by activated **macrophages** in response to the presence of Mycobacterium tuberculosis [1]. *IL4* - IL-4 is mainly involved in **B-cell activation** and is associated with **allergic responses**, not directly causing fever. - Its role does not include the **pro-inflammatory** response seen in tuberculosis infections [2]. *IL3* - IL-3 is involved in the **stimulation of hematopoiesis**, promoting the growth of various blood cells. - It does not have a significant role in **fever** or inflammation associated with tuberculosis. *IL2* - IL-2 is primarily associated with the activation and proliferation of **T-cells**, playing a role in **adaptive immunity**, not acute inflammatory responses. - It is less related to the **fever** response seen in active tuberculosis infection. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 380-381. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 380.

Question 162: Warthin-Finkeldey cells are seen in

A. Measles infection (Correct Answer)
B. Rubella infection
C. Rabies infection
D. Typhoid infection

Explanation: ***Measles infection*** - **Warthin-Finkeldey cells** are characteristic large, multinucleated giant cells with acidophilic intranuclear and intracytoplasmic inclusions found in lymphoid tissues during the prodromal phase of **measles** [1]. - These cells result from the fusion of measles virus-infected lymphocytes and are a **histological hallmark** of the disease [1]. *Rubella infection* - Rubella, or German measles, typically presents with a milder rash and **arthralgia** in adults. - While it is a viral infection, it does **not characteristically form Warthin-Finkeldey cells** in lymphoid tissue. *Rabies infection* - Rabies is a viral encephalitis primarily affecting the nervous system. - The characteristic histological finding in rabies is the presence of **Negri bodies** (eosinophilic inclusions) in the cytoplasm of neurons, not Warthin-Finkeldey cells in lymphoid tissue. *Typhoid infection* - Typhoid fever is a **bacterial infection** caused by *Salmonella Typhi*. - Histological features include **macrophage hyperplasia** and **typhoid nodules** in lymphoid tissues (like Peyer's patches), but not Warthin-Finkeldey cells. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 362-363.

Question 163: Stellate granulomas are seen in

A. Sarcoidosis
B. Cat scratch disease (Correct Answer)
C. Cryptococcosis
D. Histoplasmosis

Explanation: ***Cat scratch disease*** - **Stellate granulomas** are a characteristic histological feature of **Cat scratch disease**, caused by **Bartonella henselae**. - These granulomas are composed of macrophages, lymphocytes, and neutrophils arranged in a **star-shaped or stellate pattern**, often with central necrosis. *Sarcoidosis* - Sarcoidosis is characterized by **non-caseating granulomas**, which are typically well-formed and discrete [2], [3]. - However, they do not usually have the distinct **stellate (star-shaped) morphology** seen in cat scratch disease [3]. *Cryptococcosis* - Cryptococcosis is a fungal infection that typically presents with **granulomas containing yeasts** within macrophages. - The granulomas formed in cryptococcosis are not classically described as **stellate granulomas**. *Histoplasmosis* - Histoplasmosis is another fungal infection that can cause granuloma formation, usually with **caseous necrosis** similar to tuberculosis [1]. - The granulomas in histoplasmosis do not exhibit the **stellate architectural pattern** [1]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, p. 717. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 700-701.

Question 164: Parasitosis of extraocular eye muscles is seen in?

A. Trichinella infection (Correct Answer)
B. Cysticercus infection
C. Amoebic infection
D. Ascariasis infection

Explanation: ***Trichinella infection*** - **Trichinellosis** (caused by *Trichinella spiralis*) commonly involves the **extraocular muscles** during the muscle encystment phase [1]. - Ocular symptoms like **periorbital edema**, eosinophilic myositis of extraocular muscles, and subconjunctival hemorrhage are characteristic [1]. *Cysticercus infection* - **Cysticercosis**, caused by *Taenia solium* larvae, can affect the eye, predominantly forming **subretinal** or **vitreous cysts** [2]. - While it can involve orbital muscles, involvement of extraocular muscles is less typical and less specific than in trichinellosis [2]. *Amoebic infection* - **Amoebic infections** primarily cause **keratitis** (e.g., *Acanthamoeba*) [3] or can lead to granulomatous encephalitis in immunocompromised individuals. - They do not typically cause direct parasitosis of the extraocular muscles. *Ascariasis infection* - **Ascariasis**, caused by *Ascaris lumbricoides*, is an intestinal nematode and is not known to infect the extraocular muscles. - Ocular manifestations are rare and usually involve migration of adult worms to the orbit or eyelid, not muscle encystment. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 404-405. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 403-404. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 735-736.

Question 165: Hyaline degeneration is found in -

A. Alzheimer's disease
B. Alcoholic liver disease (Correct Answer)
C. Acute myocardial infarction
D. Acute appendicitis

Explanation: ***Alcoholic liver disease*** - **Mallory bodies**, a form of hyaline degeneration, are characteristic histologic findings in hepatocytes in alcoholic liver disease. - They represent aggregates of **intermediate filaments** and other proteins, indicating severe hepatocellular damage. *Acute myocardial infarction* - Characterized by **coagulative necrosis** of cardiac myocytes due to ischemia, not hyaline degeneration. - Inflammation and subsequent repair with **fibrosis** are key features. *Alzheimer's disease* - Defined by the presence of **senile plaques** (amyloid-beta deposits) and **neurofibrillary tangles** (hyperphosphorylated tau protein). - These are specific protein aggregates, distinct from hyaline degeneration of cellular components. *Acute appendicitis* - Involves acute inflammation of the appendix, leading to **neutrophilic infiltration** and often **fibrinopurulent exudate**. - There is no characteristic hyaline degeneration associated with this inflammatory process.

Question 166: What does Ghon's focus indicate in the context of tuberculosis?

A. Primary complex (Correct Answer)
B. Post primary tuberculosis
C. Miliary tuberculosis
D. Tuberculous lymphadenitis

Explanation: ***Primary complex*** - A **Ghon's focus** is the initial parenchymal lesion (typically subpleural) that develops during primary tuberculosis infection [1]. - The Ghon's focus, together with an enlarged regional lymph node (usually hilar or mediastinal), forms the **Ghon's complex** or **Primary complex** [2]. - When this complex undergoes calcification and healing, it is called a **Ranke complex**, which indicates past healed primary TB. *Post primary tuberculosis* - Also known as **reactivation tuberculosis** or **secondary tuberculosis**, this typically occurs years after the primary infection, usually in the apices of the lungs [2]. - It represents reactivation of dormant bacilli, not the initial primary infection lesion. - Characterized by cavitary lesions and often more severe pulmonary symptoms. *Miliary tuberculosis* - This is a form of progressive, widespread tuberculosis characterized by the presence of **tiny, millet-seed sized lesions** disseminated throughout the body via hematogenous spread [3]. - It indicates a severe and life-threatening form of TB resulting from massive lymphohematogenous dissemination. - Not related to the localized primary complex. *Tuberculous lymphadenitis* - This refers to **tuberculous infection of lymph nodes**, most commonly in the cervical region (scrofula). - While lymph node involvement is part of the primary complex, Ghon's focus specifically refers to the **parenchymal lung lesion**, not the lymph node component alone [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 379-380. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 319-320. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Respiratory Tract Disease, pp. 320-321.

Question 167: Trophozoites in stool are characteristically seen in which of the following conditions?

A. Ascariasis
B. Strongyloidiasis
C. Allergic colitis
D. Eosinophilic gastroenteritis

Explanation: **Note:** This question has significant issues. Trophozoites in stool are characteristically seen in **protozoal infections** such as *Entamoeba histolytica* (amoebiasis), *Giardia lamblia*, or *Balantidium coli* [1][2] - none of which are listed as options. ***None of the given options is medically accurate*** for characteristic trophozoites in stool. However, if forced to choose from these options: *Ascariasis* - **Ascariasis** is caused by the nematode *Ascaris lumbricoides* - Diagnosis is by identifying **ova (eggs)** in stool, not trophozoites - Trophozoites are protozoal forms, not associated with helminthic infections [2] *Strongyloidiasis* - Caused by *Strongyloides stercoralis* (nematode) - Typically diagnosed by finding **rhabditiform or filariform larvae** in stool - Not characterized by trophozoites in routine stool examination *Eosinophilic gastroenteritis* - Inflammatory condition with **eosinophilic infiltration** of GI tract - Not a parasitic infection - No trophozoites present - diagnosis is by endoscopic biopsy showing eosinophils *Allergic colitis* - Inflammatory condition related to **food allergies** (common in infants) - Presents with blood and mucus in stool with eosinophilia - Not an infectious process - no trophozoites present **Clinical Pearl:** Trophozoites (motile feeding stage of protozoa) in stool are diagnostic of **acute intestinal protozoal infections** like amoebiasis or giardiasis, where they must be identified in fresh, warm stool samples as they rapidly deteriorate [1][2]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Alimentary System Disease, pp. 364-365. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Gastrointestinal Tract, pp. 801-802.

Question 168: Bollinger bodies are seen in ?

A. Chickenpox
B. Cowpox
C. Fowlpox (Correct Answer)
D. Smallpox

Explanation: **IMPORTANT NOTE:** In **human pathology**, the term "Bollinger bodies" classically refers to **sulfur granules** seen in **actinomycosis** (Actinomyces infection), which appear as basophilic masses with radiating eosinophilic clubs. However, this question uses the **veterinary pathology** definition, where Bollinger bodies refer to viral inclusions in avian diseases. ***Fowlpox*** - In **veterinary pathology**, **Bollinger bodies** are characteristic large, eosinophilic **intracytoplasmic inclusion bodies** found in cells infected with the **fowlpox virus** (avipoxvirus). - These inclusions are visible under light microscopy and are a diagnostic feature of **fowlpox**, a widespread avian disease. - Note: Fowlpox is **not a human disease** but affects birds. *Chickenpox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is characterized by **intranuclear inclusion bodies** (Cowdry type A) [1]. - It does not form **Bollinger bodies**. *Cowpox* - Cowpox is caused by the **cowpox virus**, an **orthopoxvirus**, and produces **A-type cytoplasmic inclusion bodies** (A-type inclusions). - While these are cytoplasmic inclusions, they are not referred to as **Bollinger bodies**. *Smallpox* - Smallpox, caused by the **variola virus** (orthopoxvirus), is associated with **Guarnieri bodies**, which are **cytoplasmic inclusion bodies**. - These inclusions are distinct from **Bollinger bodies**. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 366-367.

Question 169: The histological feature known as 'Mickey Mouse Ears' is characteristically seen in:

A. Paracoccidioidomycosis (Correct Answer)
B. Tuberculosis
C. Candidiasis
D. Leptospirosis

Explanation: ***Paracoccidioidomycosis*** - This characteristic appearance, often described as a **"ship's wheel"** or **"Mickey Mouse ears"**, refers to the multiple budding yeast cells seen in **Paracoccidioides brasiliensis** on histological examination. - The central mother cell has several smaller daughter buds emerging from its periphery, resembling the iconic Mickey Mouse ears. *Candidiasis* - **Candida** infections typically manifest as **pseudohyphae** and **budding yeast** cells, but they do not form the multi-budding, "Mickey Mouse ears" configuration [1]. - The budding of Candida is usually singular or in short chains, distinct from the broad-based multi-budding of Paracoccidioides [1]. *Tuberculosis* - **Tuberculosis** is caused by **Mycobacterium tuberculosis**, a bacterium, and is characterized histologically by **granulomas** with caseous necrosis. - It does not involve yeast forms or the "Mickey Mouse ears" morphology. *Leptospirosis* - **Leptospirosis** is a **bacterial infection** caused by **Leptospira interrogans**, a spirochete, which is seen as spiral-shaped bacteria under microscopy. - This disease affects various organs and is not associated with fungal yeast forms or the "Mickey Mouse ears" appearance. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 736-737.

Question 170: In which condition is caseating necrosis most characteristically observed?

A. Leprosy
B. Infarct
C. Tuberculosis (Correct Answer)
D. Sarcoidosis

Explanation: ***Tuberculosis*** - **Caseating necrosis** is the hallmark of tuberculosis, characterized by a **cheesy, amorphous material found within granulomas** [1]. - This necrotic tissue is a result of the host’s immune response to *Mycobacterium tuberculosis* infection, involving macrophages and T-lymphocytes [4]. *Leprosy* - While leprosy (caused by *Mycobacterium leprae*) does involve granulomatous inflammation, it typically presents with **non-caseating granulomas**, especially in the **tuberculoid form** [2]. - **Caseating necrosis** is not a characteristic feature of leprosy and is rarely observed [2]. *Sarcoidosis* - Sarcoidosis is known for its **non-caseating granulomas** in various organs, particularly the lungs and lymph nodes [3]. - The absence of **central necrosis** is a key histological feature that distinguishes sarcoidosis from tuberculosis [3]. *Infarct* - An infarct is an area of **coagulative necrosis** (or liquefactive in the brain) caused by **ischemia**, where cell outlines are preserved for a period. - It does not involve the granulomatous inflammation or the **cheesy appearance** characteristic of caseating necrosis. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 383-384. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 385-386. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 109.

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