Plague as a Bioweapon Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Plague as a Bioweapon. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Plague as a Bioweapon Indian Medical PG Question 1: You are the MO in charge in a PHC and there has been a plague epidemic in your area. Which of the following measures is the LEAST appropriate for controlling epidemic?
- A. Isolation of contacts
- B. Rapid treatment of cases with streptomycin
- C. Vaccination of all susceptible individuals (Correct Answer)
- D. Early diagnosis and notification
Plague as a Bioweapon Explanation: ***Vaccination of all susceptible individuals***
- While beneficial for prevention, mass vaccination during an ongoing plague epidemic is **logistically challenging** and **too slow** to effectively control the immediate spread.
- The incubation period of plague is short, and an effective vaccine often requires multiple doses and time to induce immunity, making it less suitable for **rapid epidemic containment**.
*Isolation of contacts*
- **Isolating contacts** helps prevent the disease from spreading further by separating potentially infected individuals who may be asymptomatic or in the incubation period.
- This measure is crucial in **breaking chains of transmission** and limiting the epidemic's reach.
*Rapid treatment of cases with streptomycin*
- **Early and rapid treatment** of confirmed plague cases with effective antibiotics like **streptomycin** is a cornerstone of epidemic control, significantly reducing mortality and infectivity.
- This intervention quickly minimizes the source of infection, preventing further transmission to others.
*Early diagnosis and notification*
- **Early diagnosis** allows for prompt initiation of treatment and isolation, while **notification** triggers public health responses such as contact tracing and surveillance.
- These steps are essential for understanding the scope of the epidemic and implementing appropriate control measures efficiently.
Plague as a Bioweapon Indian Medical PG Question 2: Plague is transmitted by the bite of -
- A. Rat flea (Correct Answer)
- B. Tse-Tse fly
- C. Culex mosquito
- D. Body louse
Plague as a Bioweapon Explanation: **Correct Answer: Rat flea**
- Plague, caused by the bacterium *Yersinia pestis*, is primarily transmitted to humans through the bite of an infected **rat flea** (most commonly *Xenopsylla cheopis*)
- The fleas acquire the bacteria by feeding on infected rodents and then transmit it to humans when they bite
*Incorrect: Tse-Tse fly*
- The **Tse-Tse fly** is the primary vector for **African trypanosomiasis** (sleeping sickness), caused by species of *Trypanosoma*
- This fly is not associated with the transmission of plague
*Incorrect: Culex mosquito*
- The **Culex mosquito** is known to transmit several diseases, including **West Nile virus**, **Japanese encephalitis**, and **filariasis**
- It is not a vector for the plague bacterium *Yersinia pestis*
*Incorrect: Body louse*
- The **body louse** (*Pediculus humanus corporis*) is a vector for diseases such as **epidemic typhus** (caused by *Rickettsia prowazekii*) and **relapsing fever** (caused by *Borrella recurrentis*)
- It does not transmit plague
Plague as a Bioweapon Indian Medical PG Question 3: Which of the following is a Category C bioterrorism agent?
- A. Botulism
- B. Nipah virus (Correct Answer)
- C. Clostridium Perfringens
- D. Plague
Plague as a Bioweapon Explanation: ***Nipah virus***
- **Nipah virus** is classified as a **Category C bioterrorism agent** due to its potential for high mortality, emerging threat, and ease of genetic engineering.
- These agents are emerging pathogens that could be engineered for **mass dissemination** in the future and require ongoing surveillance.
*Botulism*
- **Botulism**, caused by *Clostridium botulinum* toxin, is a **Category A bioterrorism agent** due to its high mortality and ease of dissemination.
- Category A agents pose the greatest threat to public health and national security.
*Clostridium Perfringens*
- *Clostridium perfringens* is classified as a **Category B bioterrorism agent** because it can be used to contaminate food and water supplies.
- Category B agents are moderately easy to disseminate and cause moderate morbidity but lower mortality than Category A agents.
*Plague*
- **Plague**, caused by *Yersinia pestis*, is a **Category A bioterrorism agent** because of its high mortality, potential for aerosol dissemination, and risk of causing public panic.
- The CDC categorizes agents based on the risk they pose to national security.
Plague as a Bioweapon Indian Medical PG Question 4: A girl from Shimla presented to OPD with fever, hypotension, malaise and axillary and inguinal lymphadenopathy. Culture in glucose broth shows stalactite growth. Most likely causative organism is?
- A. Yersinia pestis (Correct Answer)
- B. Brucella abortus
- C. Coxiella burnetii
- D. Francisella tularensis
Plague as a Bioweapon Explanation: ***Yersinia pestis***
- The combination of **fever**, **hypotension**, **malaise**, and **inguinal and axillary lymphadenopathy** (buboes) is highly characteristic of **bubonic plague**, caused by *Yersinia pestis*.
- **Stalactite growth** in broth culture is a classic identifying feature of *Yersinia pestis* when incubated without agitation, due to the organism's **lipid A-modified LPS** which allows self-aggregation.
*Brucella abortus*
- *Brucella abortus* causes **brucellosis**, which presents with **undulant fever**, **arthralgia**, and **hepatosplenomegaly**, but typically not with prominent acute lymphadenopathy and hypotension to this degree.
- While it is a **facultative intracellular pathogen**, it does not exhibit stalactite growth in glucose broth.
*Coxiella burnetii*
- *Coxiella burnetii* causes **Q fever**, which is characterized by **fever**, **headache**, and **pneumonia**, often without prominent lymphadenopathy.
- It is an **obligate intracellular bacterium** and cannot be cultivated in standard glucose broth, much less show stalactite growth.
*Francisella tularensis*
- *Francisella tularensis* causes **tularemia**, which can manifest with **fever**, **lymphadenopathy** (ulceroglandular form), and **malaise**.
- However, it typically requires **specialized culture media** like cysteine-enriched agar and does not exhibit stalactite growth in glucose broth.
Plague as a Bioweapon Indian Medical PG Question 5: True statement about plague is -
- A. Septicemic plague is highly infectious
- B. Live attenuated vaccines are used
- C. Vaccine is not used to control epidemic of pneumonic plague
- D. Most important measure to control epidemic is rodent control (Correct Answer)
Plague as a Bioweapon Explanation: ***Most important measure to control epidemic is rodent control***
- **Plague** is a zoonotic disease primarily affecting rodents, with human infection occurring through flea bites from infected rodents. **Rodent control** is the fundamental and most important measure for plague control as it breaks the transmission cycle at its source.
- While immediate epidemic response includes case isolation, antibiotic treatment, and contact prophylaxis, **rodent control remains the cornerstone of comprehensive plague control programs** and is essential for both preventing and controlling epidemics.
- The bacterium *Yersinia pestis* is maintained in nature within **rodent populations**, making their management the primary long-term public health intervention.
*Septicemic plague is highly infectious*
- **Septicemic plague** is a severe form where bacteria multiply in the bloodstream but is **not infectious** from person to person - there is no person-to-person transmission.
- **Pneumonic plague** (lung infection) is the only form that is highly infectious and can spread directly between humans via respiratory droplets.
*Live attenuated vaccines are used*
- Live attenuated vaccines for plague have been used historically but are **not currently recommended or widely available** for routine use.
- Modern plague control relies on antibiotics (streptomycin, gentamicin, doxycycline) rather than vaccination.
- Vaccine development continues, but no vaccine is currently licensed for general use in most countries.
*Vaccine is not used to control epidemic of pneumonic plague*
- While this statement is technically true, it is phrased as a negative statement and doesn't represent the most important or fundamental concept about plague control.
- The question asks for the "true statement" and the positive statement about **rodent control being the most important measure** is the best answer as it represents the core principle of plague epidemiology and control.
Plague as a Bioweapon Indian Medical PG Question 6: A farmer presents to the emergency department with painful inguinal lymphadenopathy and a history of fever and flu-like symptoms. Clinical examination reveals an ulcer on the leg. Which of the following stains should be used to detect suspected bipolar-stained organisms?
- A. Albe's stain
- B. McFadyean's stain
- C. Wayson's stain (Correct Answer)
- D. Ziehl-Neelsen stain
Plague as a Bioweapon Explanation: ***Wayson's stain***
- This stain is specifically used for the detection of **Yersinia pestis**, the causative agent of **plague**, which often presents with **bipolar staining**.
- Clinical features like **painful inguinal lymphadenopathy** (buboes), fever, flu-like symptoms, and an ulcer (possibly an inoculation site) are highly suggestive of **plague**.
*Albe's stain*
- **Albe's stain** is used for demonstrating **bacterial capsules**, not for bipolar-stained organisms.
- It would not specifically identify **Yersinia pestis** in this context.
*Mc Fayden's stain*
- **McFadyen's stain** is primarily used to detect the capsule of **Bacillus anthracis** (anthrax) from smears.
- While helpful for anthrax, it is not the specific stain for bipolar staining of **Yersinia pestis**.
*Ziehl Nelson stain*
- **Ziehl-Neelsen stain** is an **acid-fast stain** used to identify organisms with high mycolic acid content in their cell walls, such as **Mycobacterium tuberculosis**.
- It is not suitable for visualizing gram-negative bacteria like **Yersinia pestis** or their bipolar staining characteristics.
Plague as a Bioweapon Indian Medical PG Question 7: Which of the following bacteria is classified as facultative anaerobe?
- A. Bacteroides
- B. Pseudomonas
- C. Escherichia (Correct Answer)
- D. Clostridium
Plague as a Bioweapon Explanation: ***Escherichia***
- *Escherichia coli* (E. coli) is a classic example of a **facultative anaerobe**, meaning it can grow in the presence or absence of oxygen.
- It uses **aerobic respiration** when oxygen is available and switches to **fermentation** or **anaerobic respiration** in an anaerobic environment.
*Bacteroides*
- *Bacteroides* species are **obligate anaerobes**, meaning they can only survive and grow in the **complete absence of oxygen**.
- They are a major component of the normal human gut flora and are sensitive to oxygen exposure.
*Pseudomonas*
- *Pseudomonas* species, such as *Pseudomonas aeruginosa*, are **obligate aerobes**, requiring **oxygen for growth and metabolism**.
- They possess enzymes like cytochrome oxidase and catalase, which are essential for aerobic respiration.
*Clostridium*
- *Clostridium* species, like *Clostridium tetani* and *Clostridium perfringens*, are **obligate anaerobes**.
- They lack the enzymes (e.g., superoxide dismutase, catalase) necessary to detoxify reactive oxygen species, making oxygen lethal to them.
Plague as a Bioweapon Indian Medical PG Question 8: A 20-year-old male patient presents to the STD clinic with a genital ulcer. The Gram stain of the smear from the ulcer shows gram-negative coccobacilli. What is the most appropriate media for culture?
- A. Blood agar with X & V factors
- B. Tellurite blood agar
- C. Thayer-Martin Medium
- D. Chocolate agar with IsoVitale X (Correct Answer)
Plague as a Bioweapon Explanation: ***Chocolate agar with IsoVitaleX***
- The presence of gram-negative coccobacilli in a genital ulcer in a young male suggests **Haemophilus ducreyi**, the causative agent of **chancroid**.
- **Chocolate agar** supplemented with **IsoVitaleX** (a growth-enhancing supplement containing X and V factors, vitamins, and cofactors) is the **optimal and standard reference medium** for culturing this fastidious organism.
- IsoVitaleX provides superior growth enhancement compared to X and V factors alone.
*Thayer-Martin Medium*
- This medium is a selective agar used primarily for the isolation of **Neisseria gonorrhoeae** and **Neisseria meningitidis**, which are gram-negative diplococci, not coccobacilli.
- While it contains antibiotics to suppress normal flora, it is not suitable for the growth of **Haemophilus ducreyi**.
*Blood agar with X & V factors*
- **Haemophilus ducreyi** requires **both X (hemin) and V (NAD) factors** for growth, which this medium theoretically provides.
- However, **chocolate agar with IsoVitaleX** is preferred because IsoVitaleX provides additional growth supplements beyond just X and V factors, and offers better selectivity and growth enhancement for this fastidious organism.
- Blood agar alone would not effectively isolate **H. ducreyi** from polymicrobial samples.
*Tellurite blood agar*
- This selective and differential medium is used for the isolation of **Corynebacterium diphtheriae**, which forms characteristic black colonies due to tellurite reduction.
- It is not appropriate for the isolation of **gram-negative coccobacilli** like **Haemophilus ducreyi**.
Plague as a Bioweapon Indian Medical PG Question 9: The ELISA test for virulence antigen is used to diagnose which type of Escherichia coli?
- A. ETEC
- B. EIEC
- C. EPEC (Correct Answer)
- D. EHEC
Plague as a Bioweapon Explanation: ***EPEC (Enteropathogenic E. coli)***
- The **ELISA test for virulence antigen** is specifically used to detect **Bundle-Forming Pilus (BFP)** and **EAF (E. coli adherence factor) plasmid antigens** in EPEC
- EPEC is a major cause of **infantile diarrhea** in developing countries
- The virulence antigen detection by ELISA is a **standard diagnostic method** for identifying typical EPEC strains
- EPEC demonstrates **localized adherence** pattern on HEp-2 cells and possesses the **LEE (locus of enterocyte effacement) pathogenicity island**
*ETEC (Enterotoxigenic E. coli)*
- ETEC causes **traveler's diarrhea** by producing **heat-labile (LT)** and **heat-stable (ST) enterotoxins**
- Diagnosis involves detecting these **specific toxins or their genes** using PCR or toxin-specific immunoassays
- ELISA for virulence antigens is not the primary diagnostic method for ETEC
*EIEC (Enteroinvasive E. coli)*
- EIEC invades intestinal epithelial cells, causing **dysentery-like illness** similar to *Shigella*
- Diagnosis relies on detecting **invasion plasmid antigen H (IpaH)** or demonstrating **invasive properties** in cell culture assays
- Serotyping and molecular methods are preferred over ELISA for virulence antigens
*EHEC (Enterohemorrhagic E. coli)*
- EHEC (particularly **O157:H7**) produces **Shiga toxins (Stx1 and Stx2)** causing hemorrhagic colitis and HUS
- Diagnosis focuses on detecting **Shiga toxins** using specific ELISA or **stx genes** by PCR
- Sorbitol-MacConkey agar is used for initial screening of O157:H7 strains
Plague as a Bioweapon Indian Medical PG Question 10: All of the following statements about Glanders are false except?
- A. It is an acute illness which presents with mild upper respiratory tract symptoms, usually self-limited.
- B. Glanders is caused by Brucella.
- C. Human infection cannot be acquired from infected animals.
- D. Belongs to class B bioterrorism agents according to CDC. (Correct Answer)
Plague as a Bioweapon Explanation: **Explanation:**
**Glanders** is a serious zoonotic disease caused by the Gram-negative bacterium ***Burkholderia mallei***. It primarily affects horses, mules, and donkeys.
**Why Option D is Correct:**
The CDC categorizes bioterrorism agents into three classes (A, B, and C) based on their potential for dissemination and severity. **Class B agents** are the second highest priority; they are moderately easy to disseminate, result in moderate morbidity rates, and low mortality rates. *Burkholderia mallei* (Glanders) and *Burkholderia pseudomallei* (Melioidosis) are both classified as **Category B** agents.
**Why the other options are Incorrect:**
* **Option A:** Glanders is **not** a mild, self-limited illness. It is a severe, often fatal disease characterized by pneumonia, bloodstream infections (sepsis), and chronic localized infections in the skin and muscle.
* **Option B:** Glanders is caused by ***Burkholderia mallei***, not *Brucella*. *Brucella* causes Brucellosis (undulant fever).
* **Option C:** Human infection **can** be acquired from infected animals. It is a zoonosis transmitted through direct contact with infected animal tissues, secretions, or inhalation of infectious aerosols.
**High-Yield NEET-PG Pearls:**
* **Causative Agent:** *Burkholderia mallei* (Non-motile, unlike *B. pseudomallei* which is motile).
* **Strauss Reaction:** A classic diagnostic test where intraperitoneal inoculation of infected material into male guinea pigs causes severe orchitis (scrotal swelling).
* **Mallein Test:** A skin test used in veterinary medicine to detect Glanders in horses.
* **Category A Agents (The "Big Six"):** Anthrax, Botulism, Plague, Smallpox, Tularemia, and Viral Hemorrhagic Fevers (Ebola/Marburg). Remember these for contrast!
More Plague as a Bioweapon Indian Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
