Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 481: Which of the following is the most common cause of Meningoencephalitis in children?

A. Mumps
B. HSV
C. Arbovirus
D. Enterovirus (Correct Answer)

Explanation: ***Enterovirus*** - **Enteroviruses** are the most frequent cause of **aseptic meningitis** and **meningoencephalitis** in children, particularly during summer and fall. - They can cause a wide range of neurological manifestations, from mild meningitis to severe encephalitis. *Mumps* - While mumps can cause **meningitis** and **encephalitis**, its incidence has significantly decreased due to widespread **MMR vaccination**. - It is less common than enteroviral infections as a cause of meningoencephalitis in the vaccinated population. *HSV* - **Herpes Simplex Virus (HSV)** is a significant cause of **viral encephalitis**, especially **temporal lobe encephalitis**, which can be severe and life-threatening. - However, HSV encephalitis is **rarer** than meningoencephalitis caused by enteroviruses in the general pediatric population. *Arbovirus* - **Arboviruses** (e.g., West Nile virus, La Crosse encephalitis virus) can cause severe meningitis and encephalitis, and their prevalence is **geographically dependent** and often associated with seasonal outbreaks. - While important in specific regions, they are not the most common overall cause of meningoencephalitis in children compared to enteroviruses.

Question 482: Which of the following is true regarding tuberculosis in children?

A. Commonly sputum negative
B. Incidence 10-15% of all TB cases
C. All of the options (Correct Answer)
D. Clinically child does not show sign of florid TB.

Explanation: ***All of the options*** - All statements — **commonly sputum negative**, **incidence 10-15% of all TB cases**, and **clinically children do not show signs of florid TB** — are generally true for tuberculosis in children. - Children often have **paucibacillary disease** and less severe clinical presentations compared to adults, making diagnosis challenging. *Commonly sputum negative* - Children often have **paucibacillary disease**, meaning fewer bacteria are present in their sputum, making cultures negative or difficult to obtain. - Their smaller airways and inability to effectively expectorate sputum contribute to the **common finding of sputum negativity**. *Incidence 10-15% of all TB cases* - Tuberculosis in children accounts for a significant but smaller proportion of the global TB burden compared to adults. - This statistic reflects that a substantial number of TB cases still occur in the pediatric population, often as contacts of adult cases. *Clinically child does not show sign of florid TB.* - Pediatric TB often presents with **non-specific symptoms** like fever, weight loss, and failure to thrive, rather than the classic severe respiratory symptoms seen in adults. - This makes clinical diagnosis challenging as **florid (severe, overt) TB signs** are less common in children due to their developing immune systems and smaller bacterial loads.

Question 483: A HIV-positive mother delivers a baby. All are true, except:

A. Risk of HIV in the baby is up to 90%. (Correct Answer)
B. HIV infection cannot be diagnosed in the baby with available methods.
C. Breast feeding can transmit HIV.
D. HIV can be transmitted from mother to child during delivery.

Explanation: ***Risk of HIV in the baby is up to 90%.*** - Without intervention, the risk of mother-to-child transmission (MTCT) of HIV ranges from **15-45%**, not 90%. - This risk can be reduced to **less than 1%** with effective interventions like antiretroviral therapy (ART) during pregnancy, elective cesarean section, and avoiding breastfeeding. *HIV infection cannot be diagnosed in the baby with available methods.* - **HIV infection CAN be diagnosed in infants** using virological tests such as **HIV DNA PCR** or **HIV RNA PCR**. - These tests detect the actual virus, unlike antibody tests which would detect maternal antibodies that crossed the placenta and can persist up to 18 months. *Breast feeding can transmit HIV.* - **Breastfeeding is a known route of HIV transmission** from an infected mother to her child. - The risk of transmission through breastfeeding is estimated to be **5-20%** and varies with viral load and duration of breastfeeding. *HIV can be transmitted from mother to child during delivery.* - **Peripartum transmission** (during labor and delivery) is the most common route of MTCT of HIV. - This occurs through exposure to maternal blood and genital secretions during the birthing process.

Question 484: Which of the following is not a common manifestation of congenital Rubella -

A. Aortic stenosis (Correct Answer)
B. PDA
C. Deafness
D. Intellectual disability

Explanation: ***Aortic stenosis*** - While **congenital heart defects** are characteristic of congenital rubella syndrome, **aortic stenosis** is NOT typically associated. - The most common cardiac anomalies in **congenital rubella syndrome** are **patent ductus arteriosus (PDA)** and **peripheral pulmonary artery stenosis**. *PDA* - **Patent ductus arteriosus** is one of the most common and classic cardiac manifestations of **congenital rubella syndrome**, occurring in 50-75% of cases. - The rubella virus interferes with normal closure of the **ductus arteriosus** during fetal development. *Deafness* - **Sensorineural deafness** is the most common manifestation of **congenital rubella syndrome**, occurring in up to 80% of cases. - The virus damages the developing **cochlea** and auditory structures, often resulting in bilateral profound hearing loss. *Intellectual disability* - **Neurological complications**, including **intellectual disability** and developmental delays, are frequent in infants with **congenital rubella syndrome**. - The virus directly infects the developing brain, leading to various degrees of **cognitive and neurological impairment**.

Question 485: Most common cause of Pyogenic Meningitis in 6 month to 2 years of age is

A. H. influenzae
B. Staphylococcus aureus
C. Neisseria meningitidis
D. Streptococcus pneumoniae (Correct Answer)

Explanation: ***Streptococcus pneumoniae*** - *Streptococcus pneumoniae* is currently the most common cause of **bacterial meningitis** in children aged 6 months to 2 years, especially after the widespread use of the *H. influenzae* type b (Hib) vaccine. - The **pneumococcal conjugate vaccine (PCV)** has significantly reduced, but not eliminated, the incidence of pneumococcal meningitis. *H. influenzae* - Before the introduction of the Hib vaccine, *H. influenzae* type b was the most common cause of **bacterial meningitis** in this age group. - Due to successful vaccination programs, its incidence has drastically declined, making **pneumococcus** more common. *Staphylococcus aureus* - *Staphylococcus aureus* is a common cause of **meningitis** associated with neurosurgical procedures, trauma, or intravenous drug use. - It is not typically the leading cause of community-acquired pyogenic meningitis in otherwise healthy children aged 6 months to 2 years. *Neisseria meningitidis* - *Neisseria meningitidis* is a significant cause of **bacterial meningitis**, especially in older children, adolescents, and young adults. - While it can occur in infants, it is generally less common than *Streptococcus pneumoniae* in the 6-month to 2-year age group.

Question 486: Which of the following statements regarding Congenital Rubella Syndrome (CRS) is FALSE?

A. Infants with Congenital Rubella Syndrome can shed virus in respiratory secretions for up to 1 year of age.
B. Risk of congenital defects is high when fetus is infected during the first trimester.
C. Cataract in CRS is always bilateral. (Correct Answer)
D. CRS is associated with increased risk of hearing loss and cardiac defects.

Explanation: ***Cataract in CRS is always bilateral.*** - While **cataracts** are a common manifestation of **Congenital Rubella Syndrome (CRS)**, they are **not always bilateral**; they can affect one or both eyes. - The severity and presentation of CRS features, including ocular defects, can vary. *Infants with Congenital Rubella Syndrome can shed virus in respiratory secretions for up to 1 year of age.* - Infants with **CRS** can indeed shed the rubella virus for an extended period, often up to a year or even longer, posing a risk of transmission to susceptible contacts. - This prolonged shedding highlights the importance of **infection control measures** when caring for affected infants. *Risk of congenital defects is high when fetus is infected during the first trimester.* - The risk of severe congenital defects is highest when the mother is infected with rubella during the **first trimester** of pregnancy, particularly in weeks 8-10. - This is due to the critical period of **organogenesis**, where viral infection can disrupt major developmental processes. *CRS is associated with increased risk of hearing loss and cardiac defects.* - **Sensorineural hearing loss** is one of the most common and significant sequelae of CRS, along with **cardiac defects** such as **patent ductus arteriosus (PDA)** and **pulmonary artery stenosis**. - These are considered part of the classic triad of CRS, which also includes eye abnormalities.

Question 487: What is the recommended duration of erythromycin prophylaxis for children exposed to pertussis?

A. 10 days of prophylactic antibiotics
B. 12 days of prophylactic antibiotics
C. 11 days of prophylactic antibiotics
D. 14 days of prophylactic antibiotics (Correct Answer)

Explanation: ***14 days of prophylactic antibiotics*** - For **post-exposure prophylaxis of pertussis** with **erythromycin**, the recommended duration is **14 days** (40-50 mg/kg/day in 4 divided doses, max 2 g/day). - This duration aims to **eradicate Bordetella pertussis** and prevent disease development or reduce severity in exposed contacts. - **Note:** Azithromycin (5 days) and clarithromycin (7 days) are shorter alternative regimens, but erythromycin specifically requires 14 days for adequate prophylaxis. *10 days of prophylactic antibiotics* - A 10-day course is **insufficient for erythromycin prophylaxis** against pertussis. - Premature discontinuation may lead to **treatment failure** and continued risk of disease transmission. *12 days of prophylactic antibiotics* - A 12-day course is **not the standard recommendation** for erythromycin-based pertussis prophylaxis. - The established CDC and AAP guidelines specify **14 days** for complete eradication. *11 days of prophylactic antibiotics* - An 11-day course is **inadequate** for erythromycin prophylaxis in pertussis-exposed children. - Adhering to the **full 14-day regimen** is crucial for optimal prevention and public health control.

Question 488: False regarding erythema infectiosum is -

A. Marked erythema of the cheeks or slapped cheek appearance often with relative circum-oral pallor
B. Infection during pregnancy can result in hydrops fetalis due to fetal anemia
C. Arthritis is a complication
D. Associated with HHV-6 (Correct Answer)

Explanation: ***Associated with HHV-6*** - Erythema infectiosum, or fifth disease, is caused by **parvovirus B19**, not **Human Herpesvirus 6 (HHV-6)** - **HHV-6** is the causative agent of **roseola infantum** (sixth disease), which presents with high fever followed by a rash - This is the **FALSE statement** making it the correct answer *Marked erythema of the cheeks or slapped cheek appearance often with relative circum-oral pallor* - This is a **classic and defining clinical feature** of erythema infectiosum - The **"slapped cheek" appearance** is often the first and most recognizable symptom in children - This statement is TRUE, therefore incorrect as an answer *Infection during pregnancy can result in hydrops fetalis due to fetal anemia* - **Parvovirus B19 infection** in pregnant women can cross the placenta and cause **severe fetal anemia** - This can result in **hydrops fetalis**, a serious and potentially fatal condition - This statement is TRUE, therefore incorrect as an answer *Arthritis is a complication* - **Arthralgia** or **arthritis** is a recognized complication of parvovirus B19 infection, particularly in adult women - The joint pain is typically symmetrical and self-limiting, resolving over weeks to months - This statement is TRUE, therefore incorrect as an answer

Question 489: A four year old female presents to the emergency room with fever and a petechial rash. A sepsis workup is performed, and parenteral antibiotics are administered. Gram-negative diplococci are identified in the CSF. Which of the following is true of this condition?

A. Antibiotic prophylaxis of fellow daycare attendees is necessary (Correct Answer)
B. The most common neurologic residual is sensorineural hearing loss
C. The presence of meningitis improves the survival rate
D. Shock is the usual cause of death, which most often occurs within 48 hours of hospitalization

Explanation: ***Antibiotic prophylaxis of fellow daycare attendees is necessary*** - The presence of **gram-negative diplococci** in the CSF and symptoms of sepsis in a four-year-old strongly suggest **meningococcal meningitis** caused by *Neisseria meningitidis*. - This condition is highly contagious, and **close contacts**, such as other children in a **daycare setting**, require **prophylactic antibiotics** (e.g., rifampin, ceftriaxone, or ciprofloxacin) to prevent secondary cases. - This is a **public health priority** and is the most definitively true statement among the options. *The most common neurologic residual is sensorineural hearing loss* - While **sensorineural hearing loss** is indeed one of the most common long-term neurological complications of bacterial meningitis (occurring in 10-30% of survivors), this option is less definitively "true" in the context of this question. - Other significant sequelae include **seizures, cognitive impairment, motor deficits**, and **learning disabilities**, with the specific frequency varying by pathogen, age, and treatment timing. - In the context of meningococcal meningitis specifically, hearing loss occurs but the question asks which statement is **true** - Option A represents a more universally true and actionable statement about meningococcal disease management. *The presence of meningitis improves the survival rate* - **Meningitis** (inflammation of the meninges) indicates a severe, invasive infection and is associated with a **higher mortality rate** and increased risk of long-term neurological complications. - The presence of meningitis signifies a more serious stage of the disease, directly **decreasing** rather than improving the survival rate. *Shock is the usual cause of death, which most often occurs within 48 hours of hospitalization* - While **septic shock** is a leading cause of death in severe meningococcal disease, particularly in fulminant cases, death most often occurs within **24-48 hours of symptom onset**, not hospitalization. - Patients who reach the hospital and receive prompt antibiotic therapy have significantly improved outcomes, and death within 48 hours **of hospitalization** (after treatment initiation) is not the most common scenario with appropriate medical care.

Question 490: In an infant born to a HIV infected mother, at what age can the ELISA test reliably diagnose HIV infection?

A. 18 months (Correct Answer)
B. 3 months
C. 9 months
D. 12 months

Explanation: ***18 months*** - At **18 months of age**, maternal HIV antibodies passed to the infant are usually no longer present, allowing for accurate detection of the infant's own antibody response via ELISA. - Before this age, a positive ELISA test might reflect the presence of **maternal antibodies** rather than true infant infection. *3 months* - An ELISA test at 3 months would not reliably diagnose HIV infection as **maternal antibodies** are still typically present in the infant's system. - Early diagnosis in infants usually requires **virological tests** (e.g., PCR for HIV DNA or RNA) that detect the virus itself, not antibodies. *9 months* - While maternal antibodies may start to wane by 9 months, they can still be present, leading to **false positive** ELISA results. - Virological testing remains the preferred method for definitive diagnosis before 18 months. *12 months* - A significant proportion of infants may still have detectable **maternal antibodies** at 12 months, making ELISA unreliable for true infection diagnosis. - Confirmation of HIV infection at this age would still ideally involve **virological testing**.

Practice by Chapter

Vaccine-Preventable Diseases

Practice Questions

Immunization Schedule

Practice Questions

Common Childhood Infections

Practice Questions

Pediatric HIV

Practice Questions

Congenital Infections

Practice Questions

Fever in Infants and Children

Practice Questions

Meningitis and Encephalitis

Practice Questions

Respiratory Tract Infections

Practice Questions

Gastrointestinal Infections

Practice Questions

Parasitic Infections

Practice Questions

Tuberculosis in Children

Practice Questions

Opportunistic Infections

Practice Questions

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