Infectious Diseases Practice Questions

Q: All of the following statements regarding measles are true, except:

Koplik spot are seen on retina. ***Koplik spot are seen on retina*** - **Koplik spots** are pathognomonic for measles and are typically found on the **buccal mucosa** (inside the cheeks), not on the retina [1]. - These are small, white, or bluish-white lesions with a red halo, appearing before the characteristic rash. *I-P is 10-14 days* - The **incubation period (I-P)** for measles, from exposure to the onset of symptoms, typically ranges from **10 to 14 days**. - This period includes the initial prodromal symptoms before the rash appears. *Long term complication may be seen in form of SSPE* - **Subacute sclerosing panencephalitis (SSPE)** is a rare, but fatal, **late complication** of measles infection [1]. - It results from persistent measles virus infection in the central nervous system, often developing years after the initial infection [1]. *Caused by RNA virus* - Measles is caused by the **measles virus**, which is a **single-stranded RNA virus** belonging to the *Paramyxoviridae* family. - It is an enveloped virus that primarily infects respiratory epithelial cells and replicates in lymphoid tissues. *Rash appears first on face* - The characteristic **maculopapular rash** of measles typically begins on the **face and behind the ears**. - It then spreads downwards to the trunk and extremities, fading in the same order [1].

Q: Which of the following has no role in the diagnosis of childhood TB?

ELISA. ***ELISA*** - ELISA (Enzyme-linked immunosorbent assay) is primarily used for detecting **antibodies** or **antigens** in various infections but has limited utility for diagnosing active childhood TB. - Due to the **variable immune response** in children and the difficulty in distinguishing latent from active TB, ELISA is not a recommended diagnostic tool for routine childhood TB diagnosis by most health organizations. *FNAC* - **Fine needle aspiration cytology (FNAC)** is a crucial tool for diagnosing childhood TB, especially in cases of lymphadenitis, by obtaining tissue for **cytological examination** and **microbiological culture**. - It allows for the detection of **acid-fast bacilli** and characteristic **granulomatous inflammation**. *Mantoux* - The **Mantoux test** (tuberculin skin test) is a valuable diagnostic aid in childhood TB, indicating past or present infection with *Mycobacterium tuberculosis*. - A positive result suggests **TB exposure** and helps in evaluating children with suspected TB, though it doesn't differentiate between latent and active disease. *CXR* - **Chest X-ray (CXR)** is an essential initial diagnostic tool for childhood TB, especially in pulmonary forms. - It can reveal characteristic findings like **hilar lymphadenopathy**, **lung infiltrates**, or **miliary patterns**, which are highly suggestive of TB in children.

Q: To prevent acute rheumatic fever, acute pharyngitis due to group A streptococci should be treated with antibiotics before:

9 days of illness. ***9 days of illness*** - Treatment of **Group A Streptococcus (GAS)** pharyngitis with appropriate antibiotics within **9 days** of symptom onset effectively prevents subsequent acute rheumatic fever. - This timeframe is crucial because it allows for clearance of the bacteria before the immune response that triggers **rheumatic fever** becomes fully established. *10 days of illness* - This duration is **beyond** the optimal window for preventing acute rheumatic fever, as the immune response may already be sufficient to initiate the disease process. - While still beneficial for symptom resolution, antibiotic treatment initiated at this point is **less effective** in preventing the sequelae of rheumatic fever. *7 days of illness* - Administering antibiotics within **7 days** of illness is highly effective and falls within the appropriate treatment window for preventing acute rheumatic fever [2]. - However, **9 days provides a slightly longer, yet still effective, cutoff**, making prevention of rheumatic fever still possible within this slightly extended period. *8 days of illness* - Antibiotic treatment at **8 days of illness** is still considered within the therapeutic window for preventing acute rheumatic fever [2]. - The goal is to clear the infection and prevent the immune system from mounting the **autoimmune response** that leads to cardiac damage [1].

Q: Koplik spots are a feature of -

Measles. ***Measles*** - **Koplik spots** are pathognomonic enanthem for measles, appearing as tiny, white spots on a reddened background, typically found on the **buccal mucosa** opposite the molars. - They usually appear 2-3 days before the characteristic **maculopapular rash** and are highly diagnostic of the disease. *Mumps* - Mumps is characterized by **parotitis** (swelling of the salivary glands), often accompanied by fever, headache, and malaise. - It does not involve Koplik spots or a generalized rash of the kind seen in measles. *Tetanus* - Tetanus is a serious bacterial infection affecting the **nervous system**, leading to muscle spasms and lockjaw. - It is caused by *Clostridium tetani* and does not present with any skin lesions or oral spots like Koplik spots. *Rubella* - Rubella, or German measles, presents with a milder rash than measles, often starting on the face and spreading to the trunk. - While it causes a rash and lymphadenopathy, **Koplik spots are not a feature** of rubella infection.

Q: Koplik's spots occur in which phase of measles -

End of prodromal phase. ***End of prodromal phase*** - **Koplik's spots**, pathognomonic for measles, typically appear 1-2 days before the onset of the **maculopapular rash**, marking the very end of the **prodromal phase**. - These are small, white spots with a bluish-white center on an erythematous base, found on the **buccal mucosa** opposite the molars. *Post exanthematous phase* - This phase occurs *after* the rash has faded and is characterized by **desquamation** and **cough**, not the appearance of Koplik's spots. - Koplik's spots would have long disappeared by this stage. *Recrudescence phase* - This term usually refers to the **reappearance of symptoms** after a period of improvement, which is not characteristic of Koplik's spots in measles. - Koplik's spots represent an initial diagnostic sign rather than a recurrent symptom. *Exanthematous phase* - The **exanthematous phase** is when the characteristic **maculopapular rash** appears and spreads, typically starting a few days *after* Koplik's spots have already emerged and are beginning to fade. - While overlap can occur, Koplik's spots are *most prominent* and diagnostic *before* the rash fully develops.

Q: An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?

Tuberculin test, then decide. ***Tuberculin test, then decide*** - A **tuberculin skin test (TST)** or **IGRA** should be performed after completing the initial chemoprophylaxis period to determine if the infant has developed **latent TB infection (LTBI)**. - According to **IAP guidelines**, if TST is **negative**, complete a total of **6 months of prophylaxis** and then administer **BCG vaccine**. - If TST is **positive**, it indicates LTBI and the infant should complete the full course of treatment as per standard protocols. - The decision to continue, modify, or stop treatment depends on **TST results** and **clinical evaluation**. *Immunise with BCG and stop prophylaxis* - **BCG vaccination** should not be given during or immediately after stopping prophylaxis without first performing a **TST**. - In TB-endemic areas, BCG is ideally given at birth, but if delayed due to TB exposure, it should only be given after **ruling out infection** with a negative TST. - Stopping prophylaxis prematurely without assessment can increase the risk of developing **active TB**. *Continue prophylaxis for 3 months* - While the standard duration of prophylaxis is **6 months total**, blindly continuing for another 3 months without TST assessment is not the most appropriate next step. - The decision to continue should be based on **TST results** performed at this juncture, not arbitrary time extension. - Prolonged unnecessary prophylaxis can lead to **drug toxicity** and **poor compliance**. *Test sputum, then decide* - An **asymptomatic infant** is unlikely to produce sputum, making this test impractical and inappropriate. - Sputum testing is used for diagnosing **active pulmonary TB**, which is not suspected in this asymptomatic child. - Sputum testing is invasive and reserved for children with **clinical symptoms** suggestive of active disease such as persistent cough, fever, or weight loss.

Q: Pathognomonic clinical feature of measles is -

Koplik spots. ***Koplik spots*** - **Koplik spots** are small, white, or bluish-white spots surrounded by a red halo, typically found on the buccal mucosa opposite the molars [1]. - They are considered **pathognomonic** for measles and usually appear 1-2 days before the generalized rash [1]. *Bitot spots* - **Bitot spots** are foamy, triangular patches on the conjunctiva, characteristic of severe **vitamin A deficiency**. - They are unrelated to measles infection. *Brushfield spots* - **Brushfield spots** are white or grayish/brown spots on the periphery of the iris. - They are a clinical feature often seen in individuals with **Down syndrome** (Trisomy 21). *Erythematous macular rash* - An **erythematous macular rash** is a common feature of measles, but it is not pathognomonic as similar rashes can be seen in other viral exanthems [1]. - The rash typically starts on the face and spreads downwards, becoming confluent [1].

Q: A 5 year old child with unprovoked dog bite, appropriate management is

Anti Rabies vaccine and Rabies Immunoglobulin. ***Anti Rabies vaccine and Rabies Immunoglobulin*** - For an **unprovoked dog bite**, especially in a child, presumptive exposure to **rabies** should be assumed, necessitating **both active immunization (vaccine)** and **passive immunization (immunoglobulin)**. - The **Rabies Immunoglobulin (RIG)** provides immediate, short-term protection, while the **rabies vaccine** stimulates the child's immune system for long-term protection. *Only Rabies Immunoglobulin at the site of bite* - While RIG provides immediate protection, it does not induce **long-term immunity**. - **Vaccination is essential** alongside RIG for sustained protection against rabies. *Kill the dog and send brain for Biopsy* - Killing the dog and performing a brain biopsy is a method to **confirm rabies in the animal**, but it does not provide immediate or preventative treatment for the exposed individual. - **Post-exposure prophylaxis (PEP)** should be initiated promptly without waiting for animal test results, especially if the animal's rabid status is unknown or suspected. *Observe the dog* - Observing the dog for **10 days** is appropriate if the bite was provoked, or if the animal is known and healthy, and **rabies risk is low**. - However, for an **unprovoked bite**, particularly from an unknown or stray dog, the risk of rabies is higher, and **post-exposure prophylaxis (PEP)** should not be delayed by observation.

Question 1

All of the following statements regarding measles are true, except:

Accepted Answer

Koplik spot are seen on retina

Answer

I-P is 10-14 days

Answer

Long term complication may be seen in form of SSPE

Answer

Caused by RNA virus

Answer

Rash appears first on face

Question 2

Which of the following has no role in the diagnosis of childhood TB?

Accepted Answer

ELISA

Answer

FNAC

Answer

Mantoux

Answer

CXR

Question 3

To prevent acute rheumatic fever, acute pharyngitis due to group A streptococci should be treated with antibiotics before:

Accepted Answer

9 days of illness

Answer

10 days of illness

Answer

7 days of illness

Answer

8 days of illness

Question 4

Koplik spots are a feature of -

Accepted Answer

Measles

Answer

Mumps

Answer

Tetanus

Answer

Rubella

Question 5

Koplik's spots occur in which phase of measles -

Accepted Answer

End of prodromal phase

Answer

Post exanthematous phase

Answer

Recrudescence phase

Answer

Exanthematous phase

Question 6

A 12-year-old boy comes to the physician because of headache, fever, nausea and vomiting. His mother reports that he has been unwell for a couple of days but seems to have become worse. In addition to his headache, he has a very stiff neck. He has no other past medical history except for well-controlled asthma. His pulse is 114/min and he has a fever of 38.5°C (101.3°F). His examination is notable for meningismus, as evidenced by discomfort elicited by movement of his neck. He also becomes visibly uncomfortable when you check his pupillary responses with a flashlight.

Which of the following patterns of cerebrospinal fluid would you expect to see if this boy turns out to have viral meningitis?

Accepted Answer

Normal opening pressure; Elevated cell count; Elevated protein; Normal glucose

Answer

Normal opening pressure; Elevated cell count; Elevated protein; Low glucose

Answer

Elevated opening pressure; Normal cell count; Normal protein; Normal glucose

Answer

Elevated opening pressure; Elevated cell count; Elevated protein; Low glucose

Question 7

An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?

Accepted Answer

Tuberculin test, then decide

Answer

Immunise with BCG and stop prophylaxis

Answer

Continue prophylaxis for 3 months

Answer

Test sputum, then decide

Question 8

An 18-month-old child presents with cellulitis of the leg and SpO2 of 88%. There is no prior history of hospitalization or illness. What is the most probable organism?

Accepted Answer

Streptococcus pneumoniae

Answer

MRSA

Answer

Streptococcus pyogenes

Answer

All of the options

Question 9

Pathognomonic clinical feature of measles is -

Accepted Answer

Koplik spots

Answer

Bitot spots

Answer

Brushfield spots

Answer

Erythematous macular rash

Question 10

A 5 year old child with unprovoked dog bite, appropriate management is

Accepted Answer

Anti Rabies vaccine and Rabies Immunoglobulin

Answer

Only Rabies Immunoglobulin at the site of bite

Answer

Kill the dog and send brain for Biopsy

Answer

Observe the dog

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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