Smallpox and Other Viral Agents — MCQs
Post-exposure prophylaxis is indicated in?
Which of the following viruses is classified as a poxvirus?
Crimean-Congo Hemorrhagic Fever is transmitted by?
A 15-year-old boy presented with fever and chills for 3 days. On examination, he was found to have delayed skin pinch time and dry oral mucosa. Identify the pathogen involved based on the provided peripheral blood smear image.
Which of the following statements about B. quintana is false?
A 28-year-old patient presents with high-grade fever, severe cough, and progressive dyspnea. The patient lives near a poultry farm where there has been a recent bird flu outbreak. What is the most appropriate diagnostic test?
The most recent influenza pandemic (2009-2010) was caused by:
The incubation period of a disease is 5-14 days. What should be the quarantine period?
Which pox virus does Variola belong to?
Targeted critical agents used in a bioterrorist event are except?
Smallpox and Other Viral Agents Indian Medical PG Practice Questions and MCQs
Question 1: Post-exposure prophylaxis is indicated in?
- A. Rabies
- B. Diphtheria
- C. HBV
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - Post-exposure prophylaxis (PEP) is a critical intervention for various infectious diseases, including **Rabies**, **Diphtheria**, and **HBV**, to prevent disease development after exposure. - The specific PEP regimen varies by disease but generally involves **vaccines**, **immunoglobulins**, or **antiviral medications**. **Rabies PEP:** - Rabies PEP is indicated after potential exposure to a rabid animal and involves a series of **rabies vaccine** doses and, for unvaccinated individuals, **rabies immune globulin (RIG)**. - Rabies is almost always fatal once symptoms appear, making timely PEP crucial. **Diphtheria PEP:** - Diphtheria PEP is recommended for close contacts of individuals with confirmed diphtheria and typically involves administering a **booster dose of diphtheria toxoid vaccine** and sometimes **antibiotics**. - This helps prevent the spread of *Corynebacterium diphtheriae* and disease development in exposed individuals. **HBV PEP:** - HBV PEP is critical after percutaneous or mucosal exposure to **HBV-infected blood** or body fluids. - It usually includes administering **hepatitis B vaccine** and, in some cases, **hepatitis B immune globulin (HBIG)**, depending on the exposed person's vaccination status and the source's HBV status.
Question 2: Which of the following viruses is classified as a poxvirus?
- A. Variola (Correct Answer)
- B. Coxsackie
- C. ECHO
- D. HSV
Explanation: ***Variola virus*** - **Variola virus** is the causative agent of **smallpox**, a historically significant and highly contagious disease. - It belongs to the **Orthopoxvirus** genus within the **Poxviridae family**, characterized by its large, brick-shaped virion and dsDNA genome. *Coxsackie virus* - **Coxsackieviruses** are part of the **Picornaviridae family**, specifically the **Enterovirus** genus. - They are known to cause a range of diseases including **hand-foot-and-mouth disease**, myocarditis, and aseptic meningitis, and are much smaller than poxviruses. *ECHO virus* - **Echoviruses** (Enteric Cytopathic Human Orphan viruses) are also members of the **Picornaviridae family** and the **Enterovirus** genus. - They are associated with diseases such as **aseptic meningitis**, gastroenteritis, and respiratory infections, completely distinct from poxviruses. *HSV (Herpes Simplex Virus)* - **Herpes Simplex Viruses** belong to the **Herpesviridae family**, characterized by a **linear dsDNA genome** and an enveloped icosahedral capsid. - They cause diseases like **oral and genital herpes** and are structurally and genetically distinct from poxviruses.
Question 3: Crimean-Congo Hemorrhagic Fever is transmitted by?
- A. Catfish
- B. Mosquitoes
- C. Ticks (Correct Answer)
- D. Mites
Explanation: ***Ticks*** - Crimean-Congo Hemorrhagic Fever (CCHF) is primarily transmitted to humans through the bite of infected **Hyalomma ticks**. - Transmission can also occur through contact with infected animal blood or tissues, or through contact with infected human body fluids. *Cat fish* - **Catfish** are aquatic animals and are not known vectors for the transmission of viral diseases like CCHF. - Their habitat and interaction with humans do not facilitate the spread of tick-borne illnesses. *Mosquitoes* - **Mosquitoes** are vectors for diseases like dengue, malaria, and Zika, but not for CCHF. - CCHF is caused by a Nairovirus, which typically requires a tick vector for its lifecycle and transmission to humans. *Mites* - While some **mites** can transmit diseases (e.g., scrub typhus), they are not the primary or significant vector for Crimean-Congo Hemorrhagic Fever. - The main vector for CCHF is specified as ticks, particularly the Hyalomma genus.
Question 4: A 15-year-old boy presented with fever and chills for 3 days. On examination, he was found to have delayed skin pinch time and dry oral mucosa. Identify the pathogen involved based on the provided peripheral blood smear image.
- A. Babesia
- B. Plasmodium vivax (Correct Answer)
- C. Plasmodium falciparum
- D. Salmonella typhi
Explanation: ***Plasmodium vivax*** - The image shows **enlarged red blood cells** infected with various stages of *Plasmodium vivax*, including trophozoites and schizonts displaying **ameboid forms**. - The presence of **Schüffner's dots**, though not distinctly visible in this specific resolution, is characteristic of *P. vivax* infection. - *P. vivax* preferentially infects **reticulocytes** and young red blood cells, leading to the characteristic RBC enlargement. *Babesia* - *Babesia* infection typically presents with **ring forms** in red blood cells that lack pigment and often form **tetrads** (Maltese cross appearance), which are not seen here. - While it can cause fever and chills, the morphology of the parasites in the image is inconsistent with *Babesia*. *Plasmodium falciparum* - *P. falciparum* characteristically presents with **multiple small ring forms** in a single red blood cell and **crescent-shaped gametocytes**. - It infects red blood cells of all ages, does not typically enlarge the red blood cells, and early trophozoites (*ring forms*) are the most common stage seen in peripheral blood, which differs from the image. *Salmonella typhi* - *Salmonella typhi* is a bacterium that causes **typhoid fever** and is a systemic infection. - It does not infect red blood cells or present with intraerythrocytic parasites on a peripheral blood smear; diagnosis is typically made by **blood culture**.
Question 5: Which of the following statements about B. quintana is false?
- A. Tick is the vector (Correct Answer)
- B. Recurrence is common
- C. Causes trench fever
- D. Not detected by Weil-Felix reaction
Explanation: ***Tick is the vector*** - This statement is **false** because *Bartonella quintana* (B. quintana) is primarily transmitted by the **human body louse**, not ticks. - The disease it causes, **trench fever**, was historically associated with crowded and unsanitary conditions where lice thrive. *Causes trench fever* - *B. quintana* is the causative agent of **trench fever**, a louse-borne illness characterized by recurrent febrile episodes. - This symptom was highly prevalent among soldiers in the trenches during World War I. *Recurrence is common* - **Relapsing fever** (recurrence) is a characteristic feature of trench fever, often occurring several times over weeks or months. - This recurrence is due to the **intracellular survival of *Bartonella* species** within erythrocytes and endothelial cells, making clearance difficult. *Not detected by Weil-Felix reaction* - The **Weil-Felix reaction** is a serological test used to detect certain rickettsial infections, which cross-react with *Proteus* antigens. - *Bartonella quintana* infections **do not typically produce antibodies** that cross-react with *Proteus* antigens; therefore, the Weil-Felix test would not be positive for trench fever.
Question 6: A 28-year-old patient presents with high-grade fever, severe cough, and progressive dyspnea. The patient lives near a poultry farm where there has been a recent bird flu outbreak. What is the most appropriate diagnostic test?
- A. Virus isolation
- B. Rapid antigen test
- C. RT-PCR (Correct Answer)
- D. Antibody detection
Explanation: ***RT-PCR*** - **Reverse transcription polymerase chain reaction (RT-PCR)** is the gold standard for diagnosing avian influenza (bird flu) due to its high sensitivity and specificity. - It directly detects the **viral RNA** and can confirm active infection, which is crucial given the recent bird flu outbreak and the patient's symptoms. *Virus isolation* - **Virus isolation** is a highly specific method but is time-consuming and requires specialized laboratory facilities, making it less suitable for rapid diagnosis in an acute clinical setting. - It is often used for **viral characterization** and surveillance rather than initial patient diagnosis. *Rapid antigen test* - **Rapid antigen tests** for influenza generally have lower sensitivity for avian influenza compared to RT-PCR, leading to a higher risk of false negatives. - While quick, their reduced accuracy might delay appropriate patient management, especially in a potential outbreak scenario. *Antibody detection* - **Antibody detection** (serology) indicates past exposure or infection, as antibodies typically take several days to weeks to develop. - It is not suitable for diagnosing an **acute, active infection** like the current presentation of fever, headache, and rash due to the lag in antibody production.
Question 7: The most recent influenza pandemic (2009-2010) was caused by:
- A. H5N1
- B. H3N2
- C. H7N7
- D. H1N1 (Correct Answer)
Explanation: ***H1N1 (2009 Swine Flu Pandemic)*** - The **2009-2010 influenza pandemic** was indeed caused by a novel strain of **influenza A virus subtype H1N1**, commonly referred to as **swine flu**. - This strain had a unique genetic makeup, being a reassortant virus with genes from **avian**, **swine**, and **human influenza viruses**. *H5N1 (Bird Flu)* - While **H5N1** has caused significant outbreaks and fatalities, particularly in poultry and humans exposed to infected birds, it did not cause the **2009-2010 pandemic**. - **H5N1** has a high mortality rate in humans but has not acquired efficient human-to-human transmissibility for a widespread pandemic. *H3N2 (Seasonal Flu)* - **H3N2** is a common subtype of **influenza A virus** that circulates annually and contributes to **seasonal influenza epidemics**. - It was not responsible for the **2009-2010 pandemic**, which was characterized by a novel H1N1 strain. *H7N7 (Avian Influenza)* - **H7N7** is an **avian influenza virus** that has caused outbreaks primarily in birds and, on rare occasions, has been transmitted to humans, typically in occupational settings. - It did not cause the **2009-2010 global influenza pandemic**.
Question 8: The incubation period of a disease is 5-14 days. What should be the quarantine period?
- A. 5 days
- B. 10 days
- C. 14 days (Correct Answer)
- D. 20 days
Explanation: ***14 days*** - The **quarantine period** should be equal to or slightly longer than the **maximum incubation period** of the disease. - In this case, 14 days covers the entire potential incubation range of 5-14 days, ensuring any exposed individual would develop symptoms within this period if infected. *5 days* - A 5-day quarantine period is too short as it is equal to the **minimum incubation period** and would not capture individuals with longer incubation times. - An individual could become symptomatic and transmit the disease after the 5-day quarantine if their incubation period was longer. *10 days* - A 10-day quarantine period is insufficient as it falls short of the **maximum incubation period** of 14 days. - An individual could still develop symptoms and become infectious up to 4 days after completing a 10-day quarantine. *20 days* - A 20-day quarantine period is unnecessarily long as it exceeds the **maximum incubation period**. - While it ensures coverage of the incubation period, it imposes excessive burden and resource utilization without added public health benefit.
Question 9: Which pox virus does Variola belong to?
- A. Parapoxvirus
- B. Orthopoxvirus (Correct Answer)
- C. Yatapox virus
- D. Molluscipox virus
Explanation: ***Orthopoxvirus*** - **Variola virus**, the causative agent of **smallpox**, is a member of the **Orthopoxvirus genus**. - Other notable members of this genus include **vaccinia virus** (used in smallpox vaccine) and **monkeypox virus**. *Parapoxvirus* - This genus includes viruses such as **Orf virus**, which causes contagious pustular dermatitis in sheep and goats, occasionally transmitted to humans. - Parapoxviruses typically cause localized skin lesions and are not associated with **smallpox**. *Yatapox virus* - The **Yatapox virus genus** includes the **Tanapox virus** and **Yabapox virus**, which primarily affect monkeys but can cause mild, self-limiting skin lesions in humans. - They are distinct from the **Variola virus** and do not cause smallpox. *Molluscipox virus* - This genus contains **Molluscum contagiosum virus**, which causes **molluscum contagiosum**, a common skin infection characterized by small, flesh-colored, dome-shaped papules. - It is genetically and clinically distinct from **Variola virus**.
Question 10: Targeted critical agents used in a bioterrorist event are except?
- A. Ricinus communis
- B. Small pox
- C. Coxiella burnetii (Correct Answer)
- D. Viral hemorrhagic fevers -Junin virus
Explanation: ***Coxiella burnetii*** - This is the **correct answer** as it is classified as a **Category B biological agent**, not a Category A critical agent. - While *C. burnetii* causes **Q fever** and has high infectivity with potential for widespread illness, it typically has **lower mortality rates** compared to Category A agents. - Category B agents are second-priority because they are moderately easy to disseminate but cause lower mortality than Category A agents. *Ricinus communis* - This refers to **ricin toxin** derived from castor beans, classified as a **Category B agent**. - However, ricin is considered more dangerous than Q fever due to its potent toxicity and lack of antidote. - Can cause severe multi-organ damage upon inhalation or ingestion, though less lethal than Category A agents. *Smallpox* - Caused by **variola virus**, classified as a **Category A critical agent**. - High infectivity, severe illness, high mortality rate, and lack of natural immunity in most populations. - Historical use as a bioweapon and potential for rapid global spread make it a top-tier threat. *Viral hemorrhagic fevers - Junin virus* - **Category A critical agent** due to high infectivity, severe disease presentation, and high mortality rates. - Includes agents like Ebola, Marburg, Lassa, and Junin viruses that cause severe multi-system disease. - Person-to-person transmission potential and lack of effective treatments make these priority threats.
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