Infectious Diseases — MCQs

A 5 year old boy is detected to be HBsAg positive on two separate occasions during a screening program for hepatitis B. He is otherwise asymptomatic. Child was given three doses of recombinant hepatitis B vaccine at the age of 1 year. His mother was treated for chronic hepatitis B infection around the same time. The next relevant step for further investigating the child would be to –

Q396

Which statement is FALSE about '100 Day Cough'?

Q397

A mother brings her 9 month old child for vaccination. Which of the following statements is false regarding immunization of Japanese encephalitis?

Q398

Koplik spots are characteristic of:-

Q399

Which of the following is the most common clinical manifestation of human parvovirus B19?

Q400

Reye's syndrome following influenza is most commonly associated with -

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 391: Most common complication of mumps in children:

A. Aseptic meningitis (Correct Answer)
B. Myocarditis
C. Pancreatitis
D. Orchitis

Explanation: ***Aseptic meningitis*** - **Aseptic meningitis** is the most frequent complication of mumps, occurring in approximately 10-30% of cases, primarily in children. - It usually presents with mild symptoms like **headache**, **fever**, and **nuchal rigidity** and typically resolves without specific treatment or long-term sequelae. - This is a benign, self-limiting condition that represents **CNS involvement** during mumps infection. *Myocarditis* - Myocarditis can occur as a complication of mumps, but it is **relatively rare** and much less common than aseptic meningitis. - While it can be serious, it is not considered the most common complication in children. *Orchitis* - Orchitis (inflammation of the testicles) is a well-known complication of mumps, but it primarily affects **post-pubertal males** and is uncommon in prepubertal children. - In the pediatric age group specifically, it is **less common than aseptic meningitis**. - Can lead to testicular atrophy and potential fertility issues in adults. *Pancreatitis* - Pancreatitis is a known but **less frequent complication**, occurring in about 2-5% of mumps cases. - While it can cause abdominal pain and elevated serum amylase, it is not the most common complication of mumps in children.

Question 392: A child presents with complaints of cough. Characteristic inspiratory whoop present. He is not immunised. Sample for investigation is:

A. Nasopharyngeal swab (Correct Answer)
B. Sputum culture
C. Tracheal aspiration
D. Cough plate culture

Explanation: ***Nasopharyngeal swab*** - A **nasopharyngeal swab** is the preferred sample for diagnosing **whooping cough** (pertussis) caused by *Bordetella pertussis*, especially for PCR testing. - This method provides the best yield for detecting the bacterium which colonizes the **nasopharynx**. *Sputum culture* - **Sputum culture** is generally not recommended for diagnosing pertussis as *Bordetella pertussis* is a fastidious organism and less likely to be found in sputum. - Sputum collection can also be challenging and less effective in young children. *Tracheal aspiration* - **Tracheal aspiration** is an invasive procedure and is generally reserved for critically ill patients or those with specific indications like ventilator-associated pneumonia, not routine pertussis diagnosis. - The primary site for *Bordetella pertussis* colonization is the nasopharynx, not typically deep within the trachea for initial sampling. *Cough plate culture* - **Cough plate culture** involves exposing a culture medium directly to a patient's cough, but it is an older technique with lower sensitivity and specificity compared to nasopharyngeal swabs and PCR. - Modern diagnostic methods, such as PCR from nasopharyngeal samples, offer faster and more accurate results for pertussis.

Question 393: Which of the following is true regarding Typhoid in children -

A. Urine culture is positive in 4 to 6 days
B. Leukocytosis is characteristic
C. Encephalitis is common
D. Mild splenomegaly is usual (Correct Answer)

Explanation: ***Mild splenomegaly is usual*** - **Splenomegaly** is a common finding in children with typhoid fever, often mild to moderate. - The spleen may enlarge due to bacterial dissemination and the body's immune response to the infection. *Urine culture is positive in 4 to 6 days* - **Urine culture** typically becomes positive much later in the course of typhoid fever, usually after the first week or even later, once bacteria have disseminated more widely. - **Blood culture** is the most reliable diagnostic test in the first week of illness. *Leukocytosis is characteristic* - **Leukopenia** (low white blood cell count), sometimes with relative lymphocytosis, is characteristic of typhoid fever, especially in the early stages. - **Leukocytosis** (high white blood cell count) is atypical and may suggest a different infection or a complication. *Encephalitis is common* - **Encephalopathy** (altered mental status, confusion) can occur in severe cases of typhoid fever, sometimes referred to as "typhoid encephalopathy." - True **encephalitis** (inflammation of the brain parenchyma) is a less common neurological complication and is not characteristic for every case.

Question 394: Roseola infantum is caused by ______

A. Rubeola
B. HHV 6 (Correct Answer)
C. Rubella
D. HHV 5

Explanation: ***HHV 6*** - **Roseola infantum**, also known as **exanthem subitum**, is characteristically caused by **Human Herpesvirus 6 (HHV 6)**. - This virus typically causes an illness in infants and young children featuring a **high fever for several days** followed by a **maculopapular rash** after the fever subsides. *Rubeola* - **Rubeola** is the virus responsible for **measles**, a disease distinctly different from roseola with prominent symptoms like **Koplik spots** and a rash that appears during the fever. - Measles rash typically starts on the face and spreads downwards, while roseola rash appears after the fever breaks. *Rubella* - **Rubella** causes **German measles**, characterized by a **milder rash** and relatively few systemic symptoms compared to measles. - Unlike roseola, rubella's rash often appears coincident with or shortly after the fever, and the fever is generally not as high. *HHV 5* - **HHV 5** refers to **Cytomegalovirus (CMV)**, which is associated with a wide range of clinical manifestations, including congenital infections, mononucleosis-like syndrome, and opportunistic infections in immunocompromised individuals. - CMV typically does not cause the classic fever-then-rash presentation seen in roseola infantum.

Question 395: A 5 year old boy is detected to be HBsAg positive on two separate occasions during a screening program for hepatitis B. He is otherwise asymptomatic. Child was given three doses of recombinant hepatitis B vaccine at the age of 1 year. His mother was treated for chronic hepatitis B infection around the same time. The next relevant step for further investigating the child would be to –

A. Repeat another course of Hepatitis B vaccine
B. Repeat HBsAg
C. Obtain HBeAg and anti-HBe levels (Correct Answer)
D. Obtain anti HBs levels

Explanation: **Obtain HBeAg and anti–HBe levels** - Given the child is **HBsAg positive** on two separate occasions and has a mother with **chronic hepatitis B**, evaluating **HBeAg** and **anti-HBe levels** is crucial to determine if the child is in a high replicative immune tolerant phase or an immune clearance phase. - This information helps differentiate between persistent infection, risk of vertical transmission, and guides subsequent management, including the potential for antiviral therapy and monitoring requirements. *Repeat another course of Hepatitis B vaccine* - Repeating the vaccine is not indicated as the child is already **HBsAg positive**, indicating an active infection or carrier state, not a need for further immunization. - Vaccination aims to prevent infection, but in this case, the child is already confirmed to be infected. *Repeat HBsAg* - The question states the child was detected to be **HBsAg positive on two separate occasions**, making another repeat unnecessary for confirmation of infection. - The next step should aim to characterize the infection rather than re-confirm its presence. *Obtain anti HBs levels* - **Anti-HBs antibodies** indicate immunity from vaccination or resolved infection. Since the child is **HBsAg positive**, indicating active infection, anti-HBs levels would likely be negative or low and would not provide critical information about the current stage of infection. - The focus should be on characterizing the active infection, not assessing protective immunity.

Question 396: Which statement is FALSE about '100 Day Cough'?

A. Incubation period is 7-14 days.
B. Erythromycin is the drug of choice.
C. There is no subclinical or chronic carrier state.
D. Incidence and fatality are more common in males than females. (Correct Answer)

Explanation: ***Incidence and fatality are more common in males than females.*** - This statement is **false** as written as a general statement, though the evidence is nuanced. In **infants**, particularly those under 6 months, **male sex is actually a recognized risk factor** for severe pertussis and higher mortality. However, in older age groups and for overall disease incidence (including milder cases), the sex distribution is more equal or may vary by region. - The statement is marked false because it presents an overly broad generalization. **Severe disease and fatality** in the most vulnerable population (young infants) actually shows **male predominance**, but mild/moderate disease across all ages doesn't consistently show this pattern. - Current epidemiological data shows **case fatality rates are higher in male infants**, attributed to smaller airways and immunological differences. *Incubation period is 7-14 days.* - This statement is **true**. The incubation period for **pertussis** (100-day cough) is typically **7 to 10 days**, with a range of 6 to 20 days. - This is the period when *Bordetella pertussis* multiplies in the respiratory tract before symptomatic illness begins. *Erythromycin is the drug of choice.* - This statement is **true**. **Macrolide antibiotics** including erythromycin, azithromycin, and clarithromycin are the **drugs of choice** for treating pertussis. - Most effective when given during the **catarrhal stage** (first 1-2 weeks) to reduce symptom severity and transmission. Also used for post-exposure prophylaxis in contacts. - **Azithromycin** is now often preferred over erythromycin due to better tolerability and shorter course. *There is no subclinical or chronic carrier state.* - This statement is **true**. **Pertussis does not establish a chronic carrier state**. Unlike some bacterial infections, *Bordetella pertussis* does not persist asymptomatically long-term. - Infected individuals typically develop symptomatic disease, though symptoms may be mild or atypical in vaccinated individuals or adults. - Once the infection clears (with or without treatment), the organism is eliminated and does not persist.

Question 397: A mother brings her 9 month old child for vaccination. Which of the following statements is false regarding immunization of Japanese encephalitis?

A. Live vaccine SA 14-14-2 is administered intramuscularly (Correct Answer)
B. 2 doses are recommended at age 9 months and 18 months
C. The live attenuated vaccine can be given to adolescents
D. The strain used for live vaccine is JE strain SA 14-14-2

Explanation: ***Live vaccine SA 14-14-2 is administered intramuscularly*** - The live attenuated **JE vaccine SA 14-14-2** is approved for subcutaneous (SC) administration, not intramuscular (IM). - While some vaccines are given IM, the specific instructions for this live JE vaccine specify the **subcutaneous route**. *2 doses are recommended at age 9 months and 18 months* - This statement is **true** for the live attenuated Japanese Encephalitis vaccine, as two doses at 9 and 18 months provide good long-term protection. - This schedule is commonly adopted in JE-endemic regions for comprehensive immunization. *The live attenuated vaccine can be given to adolescents* - This statement is **true**, as the live attenuated JE vaccine is approved for use across a wide age range, including adolescents, for primary immunization or as a booster. - The vaccine is generally well-tolerated and effective in this age group. *The strain used for live vaccine is JE strain SA 14-14-2* - This statement is **true**; the **SA 14-14-2 strain** is the most widely used and well-characterized live attenuated Japanese Encephalitis vaccine globally. - It has demonstrated high efficacy and a good safety profile in preventing JE caused by various genotypes.

Question 398: Koplik spots are characteristic of:-

A. Chicken pox
B. HIV
C. Measles (Correct Answer)
D. Mumps

Explanation: ***Measles*** - **Koplik spots** are small, white, or bluish-white spots on an erythematous base on the buccal mucosa, typically appearing 1-2 days before the generalized rash of measles. - They are considered a **pathognomonic sign** of measles infection. *Chicken pox* - Characterized by a **pruritic rash** that progresses from macules to papules, vesicles, and scabs. - It does not involve Koplik spots; its oral lesions are typically **aphthous ulcers** or vesicles. *HIV* - A retroviral infection that can lead to acquired immunodeficiency syndrome (AIDS). - Oral manifestations of HIV include **oral candidiasis**, **hairy leukoplakia**, and **Kaposi's sarcoma**, but not Koplik spots. *Mumps* - A viral infection primarily affecting the **salivary glands**, causing painful swelling (parotitis). - While it can cause oral symptoms like difficulty swallowing, it is not associated with the presence of Koplik spots.

Question 399: Which of the following is the most common clinical manifestation of human parvovirus B19?

A. Hydrops fetalis
B. Aplastic crisis in hemolytic anemia patients
C. Erythema infectiosum (Correct Answer)
D. Anemia in neonatal period

Explanation: ***Erythema infectiosum*** - This is also known as **fifth disease** and is characterized by a "slapped cheek" rash on the face followed by a lacy rash on the trunk and limbs. - It is a common and usually mild illness in children, caused by **human parvovirus B19**. *Hydrops fetalis* - While parvovirus B19 can cause hydrops fetalis in pregnant women by infecting fetal red blood cell precursors, it is a severe, less common manifestation rather than a **common clinical presentation** across all infected individuals. - Hydrops fetalis is characterized by **extensive fetal edema** and effusions, leading to high mortality. *Aplastic crisis in hemolytic anemia patients* - Parvovirus B19 can cause transient aplastic crisis, especially in individuals with **pre-existing hemolytic anemias** (e.g., sickle cell disease), due to its tropism for erythroid progenitor cells. - However, this is a specific complication in a susceptible population, not the **most common clinical manifestation** in the general population. *Anemia in neonatal period* - Parvovirus B19 infection can cause severe anemia in newborns if the mother is infected during pregnancy. - However, direct infection causing anemia in the neonatal period is less common than erythema infectiosum, which is widespread in children.

Question 400: Reye's syndrome following influenza is most commonly associated with -

A. Type C
B. Type A
C. Type B (Correct Answer)
D. All of the options

Explanation: ***Type B*** - Reye's syndrome is **classically and most strongly associated** with **influenza B virus infection** in children who have been given **aspirin** for symptomatic relief. - The combination of **viral infection (especially influenza B)** and **aspirin use** leads to mitochondrial dysfunction, particularly affecting the liver and brain. - Epidemiological studies during the peak incidence years showed a **stronger association with influenza B** than with other influenza types. *Type A* - While influenza A can precede Reye's syndrome, particularly during pandemics, the **classical and stronger epidemiological association** is with influenza B. - Both influenza A and B have been implicated, but **type B predominates** in most case series and textbook descriptions. *Type C* - Influenza C viruses typically cause **mild respiratory illness** and are rarely associated with severe complications. - There is **no significant association** between influenza C and the development of Reye's syndrome. *All of the options* - This is incorrect because Reye's syndrome exhibits a **stronger and more consistent association specifically with influenza B** compared to other influenza types. - While other viral infections (particularly **varicella-zoster virus**) can also precede Reye's syndrome, among influenza types, **type B is the most implicated**.

Practice by Chapter

Vaccine-Preventable Diseases

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Immunization Schedule

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Common Childhood Infections

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Pediatric HIV

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Congenital Infections

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Fever in Infants and Children

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Meningitis and Encephalitis

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Respiratory Tract Infections

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Gastrointestinal Infections

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Parasitic Infections

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Tuberculosis in Children

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Opportunistic Infections

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