Arboviruses Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Arboviruses. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Arboviruses Indian Medical PG Question 1: KFD is transmitted by:
- A. Sandfly
- B. Mosquito
- C. Tick (Correct Answer)
- D. Mite
Arboviruses Explanation: ***Tick***
- KFD, or **Kyasanur Forest Disease**, is a viral hemorrhagic fever endemic to India that is primarily transmitted by infected **ticks**, specifically *Haemaphysalis spinigera*.
- Humans can contract the disease through a **tick bite** or contact with an **infected animal**, such as monkeys, which are reservoirs for the virus.
*Sandfly*
- **Sandflies** are vectors for diseases such as **leishmaniasis** and **bartonellosis**, not Kyasanur Forest Disease.
- These insects transmit parasites or bacteria, whereas KFD is a **viral infection** transmitted by ticks.
*Mosquito*
- **Mosquitoes** are common vectors for many viral diseases, including **dengue**, **malaria**, and **chikungunya**, but they do not transmit Kyasanur Forest Disease.
- KFD is exclusively associated with **tick transmission** in its endemic regions.
*Mite*
- **Mites** can transmit diseases like **scrub typhus** (via chiggers) or cause conditions like **scabies**, but they are not vectors for Kyasanur Forest Disease.
- The primary vector for KFD is the **hard tick**.
Arboviruses Indian Medical PG Question 2: Japanese encephalitis is caused by which virus?
- A. Human retrovirus
- B. Arboviruses (Correct Answer)
- C. Enteroviruses
- D. Cytomegalovirus
Arboviruses Explanation: ***Arboviruses***
- Japanese encephalitis virus is a **flavivirus**, which belongs to the larger group of **arboviruses**.
- **Arboviruses** are viruses transmitted by arthropod vectors, such as mosquitoes, which is how Japanese encephalitis spreads.
*Human retrovirus*
- **Retroviruses** include viruses like HIV, which are characterized by their ability to reverse-transcribe RNA into DNA.
- They are not associated with encephalitis transmitted by insect vectors.
*Enteroviruses*
- **Enteroviruses** primarily replicate in the gastrointestinal tract and can cause a range of illnesses, including meningitis and hand-foot-and-mouth disease.
- They are typically spread via the fecal-oral route, not through mosquito bites.
*Cytomegalovirus*
- **Cytomegalovirus (CMV)** is a herpesvirus that can cause infections in people of all ages, often asymptomatic but particularly severe in immunocompromised individuals and neonates.
- CMV is transmitted through close contact, not via arthropod vectors.
Arboviruses Indian Medical PG Question 3: Vector for Zika virus disease is:
- A. Culex
- B. Aedes Aegypti (Correct Answer)
- C. Phlebotomus
- D. Anopheles stephensi
Arboviruses Explanation: ***Aedes aegypti***
- The **Aedes aegypti mosquito** is the primary vector responsible for transmitting the Zika virus to humans.
- This mosquito species is also known to transmit other arboviruses, including **dengue** and **chikungunya** viruses.
*Culex*
- **Culex mosquitoes** are known vectors for diseases such as **West Nile virus** and **Japanese encephalitis**.
- They are generally not considered primary vectors for the Zika virus.
*Phlebotomus*
- **Phlebotomus (sandflies)** are vectors for parasitic diseases, most notably **leishmaniasis**.
- They are not involved in the transmission of viral infections like Zika.
*Anopheles stephensi*
- **Anopheles mosquitoes**, particularly *Anopheles stephensi*, are the main vectors for **malaria**.
- They do not play a role in the transmission of the Zika virus.
Arboviruses Indian Medical PG Question 4: Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?
- A. Dengue
- B. Japanese Encephalitis
- C. Malaria
- D. Chikungunya (Correct Answer)
Arboviruses Explanation: ***Chikungunya***
- **Chikungunya** is a viral disease transmitted by mosquitoes that commonly presents with **fever**, severe **joint pain** (polyarthralgia), and a **rash**, fitting the patient's symptoms.
- Its high prevalence in **urban areas** and recent history of **mosquito bites** make it a strong diagnostic consideration.
*Dengue*
- While Dengue also causes **fever** [1] and a **rash**, it is more typically associated with **severe muscle and bone pain** ("breakbone fever"), and **hemorrhagic manifestations** or shock, which are not mentioned.
- **Joint pain** in dengue is usually less debilitating than in chikungunya.
*Japanese Encephalitis*
- This is a serious **neurological infection** characterized by **fever**, **headache**, seizures, and altered mental status, rather than prominent joint pain and rash.
- It primarily affects the **brain** and is less likely to present with this specific symptom triad.
*Malaria*
- Malaria is characterized by **cyclic fevers**, chills, sweating, and fatigue, but typically **does not present with a rash** [1] or significant joint pain.
- It is caused by a **parasite** transmitted by *Anopheles* mosquitoes, and its clinical picture differs from the described symptoms.
Arboviruses Indian Medical PG Question 5: Which virus is most commonly recognized as a prototypical viral hemorrhagic fever in endemic regions of West Africa?
- A. Lassa fever virus (Correct Answer)
- B. West Nile virus
- C. Yellow fever virus
- D. Crimean-Congo hemorrhagic fever virus
Arboviruses Explanation: ***Lassa fever virus***
- Lassa fever is a prototypical **viral hemorrhagic fever (VHF)** endemic to West Africa, caused by an **Arenavirus** transmitted through contact with rodent (Mastomys) excreta.
- Characterized by fever, hemorrhagic manifestations in severe cases (15-20%), and multi-organ involvement with high mortality in hospitalized patients.
- Represents one of the most important VHFs due to its **endemic nature** affecting millions annually in West Africa.
*Yellow fever virus*
- Yellow fever causes hemorrhagic fever with prominent **jaundice** and **hepatic necrosis**, transmitted by *Aedes* mosquitoes.
- A **Flavivirus** causing "yellow" fever due to liver damage, but vaccine-preventable and less commonly seen in modern practice in endemic regions.
*West Nile virus*
- A **Flavivirus** primarily causing **neuroinvasive disease** (meningitis, encephalitis) rather than hemorrhagic fever.
- Hemorrhagic manifestations are **extremely rare** and not characteristic of West Nile virus infection.
*Crimean-Congo hemorrhagic fever virus*
- CCHF is a severe **tick-borne VHF** (Nairovirus) with prominent hemorrhagic features and high mortality (10-40%).
- Endemic to **Africa, Asia, Eastern Europe, and Middle East** but NOT West Africa, distinguishing its geographic distribution from Lassa fever.
Arboviruses Indian Medical PG Question 6: Gram stain of CSF shows gram-negative diplococci. Culture grows on Thayer-Martin medium. Most likely organism?
- A. L. monocytogenes
- B. S. pneumoniae
- C. N. meningitidis (Correct Answer)
- D. H. influenzae
Arboviruses Explanation: ***N. meningitidis***
- The presence of **gram-negative diplococci** in CSF is a hallmark feature of *Neisseria meningitidis*.
- **Thayer-Martin medium** is a selective medium specifically designed for the isolation and growth of *Neisseria* species, inhibiting other bacterial and fungal contaminants.
*L. monocytogenes*
- *Listeria monocytogenes* is a **gram-positive rod**, which contradicts the gram stain finding of gram-negative diplococci.
- It typically causes meningitis in neonates, elderly, and immunocompromised individuals, but its morphology is distinct.
*S. pneumoniae*
- *Streptococcus pneumoniae* is a **gram-positive coccus**, often appearing in pairs (diplococci) or short chains, but it is gram-positive, not gram-negative.
- It is a common cause of bacterial meningitis but does not grow readily on Thayer-Martin medium.
*H. influenzae*
- *Haemophilus influenzae* is a **pleomorphic gram-negative coccobacillus**, not a diplococcus, and it requires specific growth factors (X and V factors) found in chocolate agar.
- While it can cause meningitis, its characteristic morphology and growth requirements differ from the description.
Arboviruses Indian Medical PG Question 7: Subdural empyema is most commonly caused by:
- A. Staphylococcus aureus
- B. Streptococcus pneumoniae (Correct Answer)
- C. H. influenzae
- D. E. coli
Arboviruses Explanation: ***Streptococcus pneumoniae***
- **_Streptococcus species_**, including **_S. pneumoniae_**, aerobic and anaerobic streptococci, and S. milleri group, are the **most common causative organisms** of **subdural empyema**, accounting for **60-70% of cases**.
- **Subdural empyema** most frequently arises from **paranasal sinusitis** (50-80% of cases) or **otitis media/mastoiditis**, infections typically caused by **streptococcal species**.
- The polymicrobial nature of sinus and ear infections explains why **streptococci** predominate in subdural empyema.
*Staphylococcus aureus*
- **_Staphylococcus aureus_** is an important cause of **subdural empyema**, particularly in **post-neurosurgical cases** and following **penetrating head trauma**.
- It accounts for approximately **10-20% of cases** but is **not the most common** overall pathogen.
- When subdural empyema follows **surgery** or **direct inoculation**, S. aureus becomes more likely than in community-acquired cases.
*H. influenzae*
- **_Haemophilus influenzae_** was historically significant before widespread **Hib vaccination**.
- Currently uncommon as a cause of **subdural empyema**, especially in vaccinated populations.
- May still be seen in unvaccinated individuals or those with underlying immunodeficiency.
*E. coli*
- **_E. coli_** is a rare cause of **subdural empyema** in adults.
- More relevant in **neonatal meningitis** and infections in **immunocompromised hosts**.
- Gram-negative bacilli are generally uncommon in subdural empyema compared to gram-positive cocci.
Arboviruses Indian Medical PG Question 8: A patient presented with meningitis, and the CSF sample was subjected to gram staining and microscopy and appears as shown in the microscopic image given below. Which of the following features / tests will be characteristic of the organism?
- A. Catalase negative, optochin sensitive. (Correct Answer)
- B. Ferments glucose and maltose but not inulin
- C. Oxidase and catalase negative, does not ferment inulin
- D. Oxidase and catalase positive and does not ferment maltose or glucose
Arboviruses Explanation: ***Catalase negative, optochin sensitive***
- The image shows **Gram-positive diplococci** (lancet-shaped, occurring in pairs), indicative of *Streptococcus pneumoniae*.
- *S. pneumoniae* is known for being **catalase-negative** and **optochin-sensitive**, which are key diagnostic features that distinguish it from other α-hemolytic streptococci.
- Additional characteristic: *S. pneumoniae* **ferments inulin** (bile soluble, quellung positive).
*Ferments glucose and maltose but not inulin*
- The phrase "does not ferment inulin" would suggest a streptococcus species OTHER than *S. pneumoniae*.
- *S. pneumoniae* characteristically **DOES ferment inulin**, which is an important diagnostic feature.
- This option is incorrect because it describes sugar fermentation that contradicts *S. pneumoniae* characteristics.
*Oxidase and catalase negative, does not ferment inulin*
- While *S. pneumoniae* is catalase-negative and oxidase-negative (oxidase test not routinely used for Gram-positive cocci), the statement "does not ferment inulin" is **incorrect** for *S. pneumoniae*.
- *S. pneumoniae* **ferments inulin**, which is a key differentiating feature from other streptococci.
- This combination of features does not match the organism shown in the microscopy.
*Oxidase and catalase positive and does not ferment maltose or glucose*
- This biochemical profile is typical for non-fermenting Gram-negative bacteria like *Pseudomonas aeruginosa*.
- Such organisms would appear as **Gram-negative rods**, not the **Gram-positive diplococci** seen in the image.
- This option is clearly incorrect based on the Gram stain morphology alone.
Arboviruses Indian Medical PG Question 9: After 5 days of birth, a baby developed poor feeding, convulsions, fever, high protein, low sugar, and low chloride levels in the cerebrospinal fluid. This is most likely due to what?
- A. Listeria monocytogenes infection (Correct Answer)
- B. Tuberculosis infection
- C. Leptospira infection
- D. Mycoplasma pneumoniae infection
Arboviruses Explanation: ***Listeria monocytogenes infection***
- **Listeria meningitis** in neonates often presents with non-specific symptoms such as **poor feeding**, **convulsions**, and fever, typically in the **first week of life**.
- The CSF profile of **high protein**, **low glucose**, and **low chloride** is characteristic of **bacterial meningitis**, which *Listeria* commonly causes in newborns.
- *Listeria* is one of the leading causes of neonatal meningitis, particularly in early-onset sepsis (within 7 days of birth).
*Tuberculosis infection*
- **Tuberculous meningitis** typically has a more insidious onset and is less common in neonates unless there's significant maternal exposure.
- While it can cause low glucose and high protein in CSF, the acute presentation in a 5-day-old neonate is atypical for TB.
- TB meningitis has a longer incubation period and wouldn't typically present this early.
*Leptospira infection*
- **Leptospirosis** is rare in neonates and usually presents with symptoms like fever, headache, and muscle pain, sometimes leading to renal or hepatic involvement.
- The CSF profile in leptospirosis would typically show **lymphocytic pleocytosis** with normal or slightly elevated protein, not the classic bacterial meningitis pattern.
*Mycoplasma pneumoniae infection*
- **Mycoplasma pneumoniae** is primarily a cause of **respiratory infections** (e.g., atypical pneumonia) in older children and adults.
- It rarely causes meningitis in neonates, and neonatal infection is highly unusual.
- When CNS involvement occurs, it's typically in older children with preceding respiratory symptoms.
Arboviruses Indian Medical PG Question 10: A 9-year-old child presented to OPD with complaints of high-grade fever, vomiting, and one episode of seizure. CSF examination was done and Gram staining of the culture showed lanceolate-shaped gram-positive diplococci. What is the probable causative agent?
- A. Haemophilus influenzae
- B. Streptococcus agalactiae
- C. Neisseria meningitidis
- D. Streptococcus pneumoniae (Correct Answer)
Arboviruses Explanation: ***Streptococcus pneumoniae***
- The description of **lanceolate-shaped gram-positive diplococci** in CSF is characteristic of *S. pneumoniae*.
- This bacterium is a common cause of **bacterial meningitis** in children and can present with high fever, vomiting, and seizures.
*Haemophilus influenzae*
- This is a **gram-negative coccobacillus**, which would appear as small, pleomorphic rods rather than lanceolate-shaped diplococci on Gram stain.
- While it causes meningitis, its Gram stain morphology is distinct from *S. pneumoniae*.
*Streptococcus agalactiae*
- *S. agalactiae* (Group B Streptococcus) is a **gram-positive coccus**, but it typically appears in **chains** and is a major cause of neonatal meningitis, not usually in a 9-year-old child.
- Its morphology on Gram stain would not be described as lanceolate diplococci.
*Neisseria meningitidis*
- *N. meningitidis* is a **gram-negative diplococcus** and would appear as kidney-bean shaped or flattened paired cocci, not gram-positive.
- Though a common cause of meningitis, the Gram stain morphology described rules it out.
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