Infectious Diseases Practice Questions

Q: False regarding erythema infectiosum is -

Associated with HHV-6. ***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

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

18 months. ***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**.

Q: Reye's Syndrome is caused by all except –

RSV. ***RSV*** - **Respiratory Syncytial Virus (RSV)** is not typically associated with Reye's Syndrome. While it can cause severe respiratory illness (bronchiolitis, pneumonia) in children, it does not have the direct link to mitochondrial dysfunction and hepatic encephalopathy characteristic of Reye's Syndrome. - Reye's Syndrome primarily occurs in children recovering from a **viral infection** (especially **influenza or varicella**) who are given **aspirin**, leading to acute encephalopathy and fatty liver. *Influenza* - **Influenza viruses (Type A and B)** are the most commonly associated viral infections with Reye's Syndrome, especially when aspirin is administered during recovery. - The combination of influenza infection and aspirin intake in children significantly increases the risk of this serious condition, which is why aspirin is contraindicated in children with febrile illnesses. *Herpes* - **Herpes simplex virus (HSV) infections** have been linked to Reye's Syndrome in some reported cases, particularly in infants and young children. - While less common than influenza or varicella-associated cases, herpes infection treated with aspirin can potentially precipitate Reye's Syndrome. *Adeno virus* - **Adenoviruses**, which cause respiratory infections and gastroenteritis, have also been implicated as a potential viral trigger for Reye's Syndrome in some reports. - The risk is heightened when salicylates (aspirin) are given to children recovering from an adenovirus infection, though this association is less established than with influenza or varicella.

Q: A 5-year-old unvaccinated child presents to the OPD with fever, red eyes, and a maculopapular rash. What is the most likely complication associated with this condition?

Pneumonia. ***Pneumonia*** - **Pneumonia** is the **most common and most likely complication of measles**, occurring in approximately **1-6% of measles cases** - The clinical presentation of **fever, red eyes (conjunctivitis), and maculopapular rash** in an **unvaccinated child** is classic for **measles (rubeola)** - Pneumonia may be due to **direct viral pneumonitis** from measles virus or **secondary bacterial infection** (most commonly *Streptococcus pneumoniae*, *Staphylococcus aureus*, or *Haemophilus influenzae*) - It is a major cause of **measles-related mortality**, particularly in young children and immunocompromised individuals *Acute myocarditis* - **Acute myocarditis** is an extremely rare complication of measles - While myocardial involvement can theoretically occur with severe viral infections, it is **not a recognized characteristic or common complication** of measles - This is not the most likely complication when compared to pneumonia, otitis media, or diarrhea *Acute nephritis* - **Acute nephritis** is not a characteristic complication of measles - It is more commonly associated with **post-streptococcal glomerulonephritis** following Group A Streptococcus infection - Kidney involvement in measles is not a well-documented or common complication *Acute orchitis* - **Acute orchitis** is a recognized complication of **mumps** virus infection, particularly in post-pubertal males (occurring in 20-30% of infected males) - It is **not associated with measles infection** - This is a classic distractor testing knowledge of viral exanthems and their specific complications

Q: Congenital Rubella Syndrome includes all except

Intracerebral hemorrhage. ***Intracerebral hemorrhage*** - This is not a typical manifestation of **Congenital Rubella Syndrome** (CRS). Symptoms of CRS primarily include sensory, cardiac, and ocular defects, not bleeding into the brain. *SN deafness* - **Sensorineural (SN) deafness** is a very common and characteristic symptom of **Congenital Rubella Syndrome**, often bilateral, due to damage to the organ of Corti. - It is one of the classic triad of manifestations of CRS. *Cataract* - **Cataracts** (clouding of the lens) are a prominent ocular defect in CRS, often leading to significant vision impairment or blindness. - Ocular defects like cataracts and **microphthalmia** are part of the classic clinical picture. *VSD* - **Ventricular Septal Defect (VSD)** is a common cardiac anomaly seen in CRS, caused by rubella virus infection during heart development. - Other common cardiac defects include **Patent Ductus Arteriosus (PDA)** and **Pulmonary Artery Stenosis**.

Q: A child presented at 18 months of age who has never been vaccinated before. Which vaccines will you administer?

DPT, OPV and MMR. ***DPT, OPV and MMR*** - Among the given options, **DPT, OPV, and MMR** represent the **most comprehensive combination** for an unvaccinated 18-month-old child. - **DPT** provides protection against Diphtheria, Pertussis, and Tetanus (in modern practice, **Pentavalent vaccine** containing DPT+Hib+Hepatitis B is preferred). - **OPV** is essential for polio protection as part of catch-up immunization. - **MMR** (Measles, Mumps, Rubella) is critical at this age, as the first dose is typically given at 9-12 months. - **Note:** A complete catch-up schedule would also include **Hepatitis B vaccine** (if not using Pentavalent), **BCG** (if never given), and **Hib vaccine**, but this option covers the maximum number of essential vaccines among the choices provided. *BCG and OPV* - While both **BCG** and **OPV** should be part of catch-up vaccination at 18 months, this combination alone is **grossly incomplete**. - It misses critical vaccines like **DPT/Pentavalent**, **Hepatitis B**, and **MMR**. - BCG should still be given at 18 months if the child was never vaccinated, despite being ideally administered at birth. *Pentavalent vaccine alone* - **Pentavalent vaccine** (DPT+Hib+Hepatitis B) is actually preferred in modern Indian immunization practice over standalone DPT. - However, giving only Pentavalent would miss **MMR** and adequate **polio vaccination** (OPV/IPV), both of which are critical at this age. - A catch-up schedule requires multiple vaccines, not just one. *MMR, OPV, Rotavirus* - **MMR** and **OPV** are indeed essential for an 18-month-old in catch-up vaccination. - However, **Rotavirus vaccine** is **contraindicated** at this age—it must be started by 14 weeks and completed by 8 months of age (maximum age for last dose varies by vaccine brand but typically 24-32 weeks). - This combination also misses **DPT/Pentavalent** and **Hepatitis B**, making it incomplete.

Q: Which vaccine is contraindicated in a 6-month-old infant whose sibling is on chemotherapy for leukemia?

Oral polio vaccine. ***Oral polio vaccine*** - The **oral polio vaccine (OPV)** is a live attenuated vaccine containing weakened but live viruses. - It is **absolutely contraindicated** in individuals with immunocompromised household contacts (like a sibling on **chemotherapy**) due to the risk of **vaccine-associated paralytic poliomyelitis (VAPP)** from shedding of the live vaccine virus. - The shed virus can be transmitted to and cause disease in immunocompromised contacts. - This is the primary reason most countries have switched to **inactivated polio vaccine (IPV)**. *Hepatitis B* - The **Hepatitis B vaccine** is an inactivated (non-live) recombinant vaccine. - It poses no risk of transmitting live virus to an immunocompromised individual. - It is safe to administer to an infant with an immunocompromised household contact. *Rotavirus vaccine* - The **Rotavirus vaccine** is also a live attenuated vaccine, and there is a **relative contraindication** when household contacts are severely immunocompromised. - The vaccine virus can be shed in stool for several days after vaccination. - However, compared to OPV, the risk of serious disease transmission is considered much lower, and some guidelines allow its use with precautions (strict hand hygiene, avoiding diaper changes by immunocompromised contacts). - In the context of this question, **OPV has a stronger absolute contraindication** than rotavirus vaccine. *DPT* - The **DPT vaccine** (Diphtheria, Pertussis, Tetanus) is an **inactivated vaccine** containing toxoids and killed bacterial components. - It is safe to administer to an infant with an immunocompromised household contact as there is no risk of shedding live pathogens.

Q: How long should a child be isolated after being diagnosed with bacterial meningitis to prevent further transmission?

Till 24 hours after starting antibiotics. ***Till 24 hours after starting antibiotics*** - This duration is crucial because, after **24 hours of effective antibiotic therapy**, the bacterial load in the nasopharynx (the primary site of transmission) is significantly reduced. - At this point, the child is generally considered **non-infectious**, and the risk of airborne transmission to others is minimal. *Till 12 hrs after admission* - This period is generally too short to ensure the child is non-infectious, as it may not be enough time for antibiotics to adequately reduce the bacterial load. - Active shedding of bacteria through respiratory droplets can still occur, posing a risk of transmission. *Till cultures become negative* - Waiting for cultures to become negative is an overly stringent and impractical approach to isolation, as it can take several days for culture results. - Clinical guidelines prioritize a more immediate and practical strategy for isolation based on antibiotic efficacy and reduced transmission risk. *Till antibiotics course is complete* - Isolating for the entire course of antibiotics is usually unnecessary and excessive, as the child is typically no longer contagious long before the full course is finished. - Prolonged isolation can create logistical challenges and is not based on the infectious period for bacterial meningitis.

Question 1

False regarding erythema infectiosum is -

Accepted Answer

Associated with HHV-6

Answer

Marked erythema of the cheeks or slapped cheek appearance often with relative circum-oral pallor

Answer

Infection during pregnancy can result in hydrops fetalis due to fetal anemia

Answer

Arthritis is a complication

Question 2

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?

Accepted Answer

Antibiotic prophylaxis of fellow daycare attendees is necessary

Answer

The most common neurologic residual is sensorineural hearing loss

Answer

The presence of meningitis improves the survival rate

Answer

Shock is the usual cause of death, which most often occurs within 48 hours of hospitalization

Question 3

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

Accepted Answer

18 months

Answer

3 months

Answer

9 months

Answer

12 months

Question 4

Reye's Syndrome is caused by all except –

Accepted Answer

RSV

Answer

Influenza

Answer

Herpes

Answer

Adeno virus

Question 5

A 5-year-old unvaccinated child presents to the OPD with fever, red eyes, and a maculopapular rash. What is the most likely complication associated with this condition?

Accepted Answer

Pneumonia

Answer

Acute myocarditis

Answer

Acute nephritis

Answer

Acute orchitis

Question 6

Congenital Rubella Syndrome includes all except

Accepted Answer

Intracerebral hemorrhage

Answer

SN deafness

Answer

Cataract

Answer

VSD

Question 7

A child presented at 18 months of age who has never been vaccinated before. Which vaccines will you administer?

Accepted Answer

DPT, OPV and MMR

Answer

BCG and OPV

Answer

Pentavalent vaccine alone

Answer

MMR, OPV, Rotavirus

Question 8

Which vaccine is contraindicated in a 6-month-old infant whose sibling is on chemotherapy for leukemia?

Accepted Answer

Oral polio vaccine

Answer

Hepatitis B

Answer

Rotavirus vaccine

Answer

DPT

Question 9

Hutchinson's triad includes?

Accepted Answer

Interstitial keratitis, Hutchinson's incisors, sensorineural deafness

Answer

Conductive deafness, malformed incisors, interstitial keratitis

Answer

Interstitial keratitis, malformed molars, conductive deafness

Answer

Interstitial keratitis, malformed incisors, conductive deafness

Question 10

How long should a child be isolated after being diagnosed with bacterial meningitis to prevent further transmission?

Accepted Answer

Till 24 hours after starting antibiotics

Answer

Till 12 hrs after admission

Answer

Till cultures become negative

Answer

Till antibiotics course is complete

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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