Emerging Infections — MCQs
Zoonotic diseases are -
Which of the following statements about Zika virus is false?
Which of the following diseases is not included in the National Vector Borne Disease Control Program?
Which of the following is the true statement regarding measures to prevent typhoid transmission in the community?
An elderly man who had been in several military conflicts during the early 1980s and received blood transfusions for injuries recently consulted his physician for a diagnosis of cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected with a virus transmitted through blood. Which virus was involved in this infection?
Multidrug-resistant (MDR) tuberculosis shows resistance to which of the following drugs?
Transition from increased prevalence of infectious and communicable diseases to man-made diseases is known as
Earliest feature of TB:
Xanthogranulomatous infection is caused by:
Which of the following are the aetiological factors associated with a communicating hydrocephalus ? I. Post haemorrhagic II. Lesions within the ventricle III. CSF infection IV. Raised CSF protein Select the correct answer using the code given below :
Emerging Infections Indian Medical PG Practice Questions and MCQs
Question 1: Zoonotic diseases are -
- A. Anthrax
- B. Plague
- C. Salmonellosis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Anthrax**, **Plague**, and **Salmonellosis** are all well-established examples of zoonotic diseases, which are infections naturally transmitted between vertebrate animals and humans. - These diseases represent a diverse spectrum of bacterial infections with significant public health implications worldwide. **Anthrax** - Caused by *Bacillus anthracis*, a spore-forming bacterium naturally found in soil that primarily affects livestock and wild herbivores. - Humans acquire infection through contact with infected animals or contaminated animal products (hides, wool, meat). - Clinical forms include cutaneous (most common), inhalational (most severe), and gastrointestinal anthrax. - Remains an important occupational hazard for veterinarians, farmers, and those handling animal products. **Plague** - Caused by *Yersinia pestis*, maintained in nature through rodent-flea cycles. - Transmission to humans occurs primarily via bites from infected fleas or direct contact with infected animals. - Historically responsible for devastating pandemics including the Black Death. - Clinical manifestations include bubonic (most common), pneumonic (person-to-person transmission possible), and septicemic plague. **Salmonellosis** - Caused by non-typhoidal *Salmonella* species, commonly colonizing the intestines of various animals including poultry, cattle, reptiles, and pets. - Humans typically acquire infection through consumption of contaminated food (undercooked meat, eggs, unpasteurized dairy) or direct animal contact. - Presents as acute gastroenteritis with diarrhea, fever, and abdominal cramps. - One of the most common foodborne zoonotic infections globally.
Question 2: Which of the following statements about Zika virus is false?
- A. Transmitted by Aedes mosquito
- B. Zika is Flavi virus
- C. Zika virus cannot be transmitted through breast milk
- D. Zika virus does not cause microcephaly (Correct Answer)
Explanation: ***Zika virus does not cause microcephaly*** - This statement is false because **Zika virus** is well-known for causing **microcephaly** and other severe birth defects in infants whose mothers were infected during pregnancy. - The association between maternal Zika infection and fetal microcephaly has been extensively documented and is one of the most critical public health concerns related to the virus. *Transmitted by Aedes mosquito* - This statement is true; **Aedes aegypti** and **Aedes albopictus** mosquitoes are the primary vectors responsible for transmitting the Zika virus to humans. - These mosquitoes are also known to transmit other arboviruses like **dengue** and **chikungunya**. *Zika is Flavi virus* - This statement is true; Zika virus belongs to the **Flaviridae family** and the *Flavivirus genus*, which also includes dengue, yellow fever, and West Nile viruses. - Members of this family are typically **single-stranded RNA viruses** with an enveloped capsid. *Zika virus cannot be transmitted through breast milk* - This statement is true; while Zika virus RNA has been detected in breast milk, there is currently **no confirmed evidence** of transmission to infants through breastfeeding. - Current guidelines from health organizations generally recommend that mothers in Zika-affected areas continue to breastfeed due to the benefits of breastfeeding outweighing the theoretical risk.
Question 3: Which of the following diseases is not included in the National Vector Borne Disease Control Program?
- A. Tuberculosis (Correct Answer)
- B. Japanese encephalitis
- C. Malaria
- D. Dengue
Explanation: ***Tuberculosis*** - **Tuberculosis** is a bacterial infection primarily affecting the lungs and is not transmitted by a vector. - It is controlled under the **National TB Elimination Programme (NTEP)**, a separate national health program. *Japanese encephalitis* - **Japanese encephalitis** is a viral disease transmitted by mosquitoes, making it a vector-borne disease. - It is one of the diseases specifically targeted by the **National Vector Borne Disease Control Program (NVBDCP)**. *Malaria* - **Malaria** is a parasitic disease transmitted by Anopheles mosquitoes, clearly categorizing it as vector-borne. - It is a primary focus of the **NVBDCP** due to its significant public health impact. *Dengue* - **Dengue** is a viral disease transmitted by Aedes mosquitoes, hence a vector-borne disease. - **Dengue control and prevention** are key objectives of the **NVBDCP**.
Question 4: Which of the following is the true statement regarding measures to prevent typhoid transmission in the community?
- A. Typhoid vaccine administration is the best method of preventing transmission.
- B. Person-to-person transmission is the primary mode of spread.
- C. Drug resistance in typhoid is not as big a problem as in TB.
- D. Hygiene practice and clean sanitation control are more important than the typhoid vaccine. (Correct Answer)
Explanation: ***Hygiene practice and clean sanitation control is more important than the typhoid vaccine.*** - **Improved sanitation**, safe water supplies, and adequate hygiene practices are fundamental in controlling the spread of **typhoid fever**, as the disease is primarily transmitted through the **oral-fecal route**. - While vaccines are an important tool, they offer only partial protection and must be combined with **robust public health infrastructure** and **sanitation measures** for effective prevention. *Typhoid vaccine administration is the best method of preventing transmission.* - Typhoid vaccines offer protection, but their effectiveness is not 100%, and they typically require **booster doses** - **Vaccination campaigns** are most effective when implemented alongside improvements in **water and sanitation infrastructure**, as vaccines alone cannot fully prevent transmission in areas with poor hygiene. *Person-to-person transmission is the primary mode of spread.* - While person-to-person transmission can occur, especially in settings with poor hygiene, the primary mode of spread for typhoid is through the **ingestion of food or water contaminated** with the feces of an infected person or carrier. - This emphasizes the crucial role of **water and food safety** rather than just focusing on direct person-to-person contact. *Drug resistance in typhoid is not as big a problem as in TB.* - **Antimicrobial resistance (AMR)** in typhoid fever, particularly to fluoroquinolones and extended-spectrum beta-lactamase (ESBL) producing strains, is a **significant and growing global health concern**, complicating treatment. - While TB also faces serious drug resistance issues, the escalating problem of **extensively drug-resistant (XDR)** and **multi-drug resistant (MDR)** typhoid strains makes it a substantial threat, impacting treatment options and increasing morbidity and mortality.
Question 5: An elderly man who had been in several military conflicts during the early 1980s and received blood transfusions for injuries recently consulted his physician for a diagnosis of cryoglobulinemia and glomerulonephritis. Additional testing revealed that he was infected with a virus transmitted through blood. Which virus was involved in this infection?
- A. Hepatitis A Virus (HAV)
- B. Hepatitis B Virus (HBV)
- C. Hepatitis C Virus (HCV) (Correct Answer)
- D. Hepatitis D Virus (HDV)
Explanation: ***Hepatitis C Virus (HCV)*** - HCV infection is a common cause of **mixed cryoglobulinemia** and can lead to **glomerulonephritis**, particularly membranoproliferative glomerulonephritis. - Before widespread screening of the blood supply, HCV was a significant risk from **blood transfusions**, especially for individuals who received them in the early 1980s [1]. *Hepatitis A Virus (HAV)* - HAV is primarily transmitted via the **fecal-oral route** and does not typically cause chronic infection or lead to cryoglobulinemia or glomerulonephritis. - It causes **acute, self-limiting hepatitis** and is not associated with blood transfusions in the context described. *Hepatitis B Virus (HBV)* - While HBV can be transmitted through blood and can cause glomerulonephritis (e.g., membranous nephropathy), it is less commonly associated with **cryoglobulinemia** in comparison to HCV. - The constellation of cryoglobulinemia and glomerulonephritis, especially with a history of transfusions in the 1980s, points more strongly to HCV. *Hepatitis D Virus (HDV)* - HDV is a **defective virus** that requires co-infection with HBV to replicate. - While it can cause severe liver disease, it is not primarily associated with **cryoglobulinemia** or glomerulonephritis as a direct cause, but rather exacerbates HBV-related complications.
Question 6: Multidrug-resistant (MDR) tuberculosis shows resistance to which of the following drugs?
- A. Isoniazid, rifampicin, and fluoroquinolone
- B. Fluoroquinolone
- C. Isoniazid, rifampicin, and kanamycin
- D. Isoniazid and rifampicin only (Correct Answer)
Explanation: ***Isoniazid and rifampicin only*** - **Multidrug-resistant (MDR) tuberculosis** is specifically defined by resistance to both **isoniazid** and **rifampicin**. - These two drugs are considered the most effective first-line anti-TB medications, making resistance to both a significant treatment challenge. *Isoniazid, rifampicin, and fluoroquinolone* - Resistance to **isoniazid**, **rifampicin**, and *any* fluoroquinolone defines **pre-extensively drug-resistant (pre-XDR) TB**, not MDR-TB. - Adding resistance to a fluoroquinolone indicates a more severe and harder-to-treat form of tuberculosis. *Fluoroquinolone* - Resistance to **fluoroquinolone** alone does not define MDR-TB; it is only one component of resistance that, when combined with resistance to isoniazid and rifampicin, signifies pre-XDR or XDR-TB. - While fluoroquinolones are important second-line drugs, their resistance in isolation does not meet the criteria for MDR-TB. *Isoniazid, rifampicin, and kanamycin* - Resistance to **isoniazid**, **rifampicin**, and *any* second-line injectable agent (like **kanamycin**, capreomycin, or amikacin) defines **extensively drug-resistant (XDR) TB**, not MDR-TB. - XDR-TB represents an even more complex and difficult form of the disease to treat, requiring highly specialized regimens.
Question 7: Transition from increased prevalence of infectious and communicable diseases to man-made diseases is known as
- A. Demographic transition
- B. Paradoxical transition
- C. Epidemiological transition (Correct Answer)
- D. Reversal of transition
Explanation: ***Epidemiological transition*** - This term describes the shift in **disease patterns** observed in many populations, moving from a predominance of **infectious and communicable diseases** to an increased prevalence of **chronic, non-communicable diseases** (often described as "man-made" due to their association with lifestyle and environmental factors). - This transition is typically linked to advancements in **public health**, sanitation, medicine, and changes in socioeconomic status. *Demographic transition* - This concept describes the historical shift from high **birth rates** and **death rates** to low birth rates and death rates as a country develops from a pre-industrial to an industrialized economic system. - While related to disease patterns through changes in population structure, it directly focuses on **population growth** and age distribution, not specific disease prevalence. *Paradoxical transition* - This is not a recognized or standard public health or demographic term for the described phenomenon. - The term "paradoxical" would imply a contradictory or unexpected outcome, which is not the primary descriptor for the shift in disease patterns. *Reversal of transition* - This term would imply a return to previous patterns, such as an increase in **infectious diseases** after a period of decline. - While possible in specific contexts (e.g., due to antibiotic resistance or weakened public health systems), it does not describe the initial shift from infectious to man-made diseases.
Question 8: Earliest feature of TB:
- A. Caseation
- B. Lymphocytosis (Correct Answer)
- C. Granuloma
- D. Langerhans' Giant cells
Explanation: ***Lymphocytosis*** - While the very earliest response to *Mycobacterium tuberculosis* involves neutrophils (acute inflammation), among the given options, **lymphocytosis is the earliest feature** [1]. - Within 2-3 weeks of initial infection, the immune system mounts a cellular response with increased **lymphocytes** (particularly CD4+ T cells) and macrophages attempting to contain the bacteria [2]. - This lymphocytic infiltration precedes the organized granuloma formation and represents the early cell-mediated immune response to TB [3]. *Granuloma* - **Granuloma formation** is a hallmark of tuberculosis, where epithelioid macrophages organize into structured aggregates to wall off the infection. - This organized structure typically develops around 3-4 weeks after infection, following the initial lymphocytic response [4]. *Caseation* - **Caseous necrosis** is the characteristic cheese-like necrosis seen in the center of TB granulomas. - This represents tissue death and is a later feature (4+ weeks), developing as granulomas mature and central hypoxia leads to cell death [4]. *Langerhans' Giant cells* - **Langhans giant cells** (not Langerhans cells of skin) are multinucleated giant cells formed by fusion of epithelioid macrophages within established granulomas [5]. - These appear in mature granulomas and represent a late organized response, not an early feature. **References:** [1] 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. 195-196. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 379-380. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, p. 380. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 380-381. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 109.
Question 9: Xanthogranulomatous infection is caused by:
- A. Nephrolithiasis
- B. Proteus Mirabilis
- C. All of the options (Correct Answer)
- D. Urinary obstruction
Explanation: ***All of the options*** - **Xanthogranulomatous pyelonephritis (XGP)** is a severe, chronic infectious process of the kidney, often associated with a combination of factors including **urinary tract obstruction**, specific bacterial infections, and the presence of kidney stones (nephrolithiasis) [1]. - **Proteus mirabilis** is a common cause of XGP due to its ability to produce urease, which hydrolyzes urea into ammonia, increasing urinary pH and promoting the formation of struvite stones, thus acting in concert with obstruction and stones [1]. *Nephrolithiasis* - While **kidney stones** are a major predisposing factor for XGP, they do not solely cause the infection; they primarily create an environment conducive to bacterial colonization and obstruction. - The presence of stones, particularly **struvite stones**, can lead to persistent infection and the characteristic inflammatory response seen in XGP. *Proteus Mirabilis* - **Proteus mirabilis** is frequently isolated in cases of XGP, but it typically acts in conjunction with urinary obstruction and/or nephrolithiasis [1]. - This bacterium contributes significantly to the pathophysiology by promoting stone formation and maintaining a chronic infectious state, but it is not the sole cause. *Urinary obstruction* - **Urinary tract obstruction** is a key predisposing factor that prevents proper drainage, leading to stasis and increasing susceptibility to infection [1]. - While essential for the development of XGP, obstruction alone does not directly cause the characteristic xanthogranulomatous inflammation without the presence of bacteria and often stones. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 939-940.
Question 10: Which of the following are the aetiological factors associated with a communicating hydrocephalus ? I. Post haemorrhagic II. Lesions within the ventricle III. CSF infection IV. Raised CSF protein Select the correct answer using the code given below :
- A. I, II and III
- B. II, III and IV
- C. I, II and IV
- D. I, III and IV (Correct Answer)
Explanation: ***I, III and IV*** - **Communicating hydrocephalus** occurs when there is impaired CSF absorption in the **subarachnoid space** despite a patent ventricular system. - **Post-hemorrhagic**, **CSF infection** (meningitis), and **raised CSF protein** (e.g., from tumors or inflammation) can all obstruct the arachnoid villi, preventing proper CSF reabsorption [1]. *I, II and III* - While **post-hemorrhagic** and **CSF infection** are causes of communicating hydrocephalus, **lesions within the ventricle** typically cause **non-communicating (obstructive) hydrocephalus** by blocking CSF flow *within* the ventricular system itself [1]. - This option incorrectly includes an obstructive cause and omits **raised CSF protein**, which is a known cause of impaired CSF absorption. *II, III and IV* - This option incorrectly includes **lesions within the ventricle** as a cause of communicating hydrocephalus, which usually leads to **non-communicating hydrocephalus** [1]. - It correctly identifies **CSF infection** and **raised CSF protein** but omits **post-hemorrhagic** causes, which are a common etiology [1]. *I, II and IV* - This option incorrectly includes **lesions within the ventricle**, which typically cause **non-communicating hydrocephalus** [1]. - While **post-hemorrhagic** and **raised CSF protein** are valid causes, the inclusion of an obstructive cause makes this option incorrect for *communicating* hydrocephalus. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Manifestations Of Central And Peripheral Nervous System Disease, pp. 703-704.
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