Infectious Diseases Practice Questions

Q: Reye's syndrome in children is commonly associated with aspirin use during which type of infection?

Influenza virus. ***Influenza virus*** - Reye's syndrome is a rare but severe condition characterized by **acute encephalopathy and fatty liver infiltration** that predominantly affects children recovering from viral infections - **Aspirin use during influenza** is one of the two most strongly documented associations with Reye's syndrome, leading to contraindication of aspirin in children with febrile illnesses - The incidence of Reye's syndrome dropped dramatically after public health warnings against aspirin use in children with influenza-like illnesses *Varicella (Chickenpox)* - Varicella is the **other major viral infection** strongly associated with Reye's syndrome when aspirin is used - Both influenza and varicella are considered the two primary precipitating viral infections - In competitive exam context, when both are options, understanding the equal significance is important, though influenza is often cited first in classical teaching *HIV* - **HIV is a chronic infection** and not an acute febrile viral illness where aspirin would typically be used for symptomatic relief - Reye's syndrome is specifically associated with **acute viral illnesses** (influenza and varicella) where aspirin might be administered for fever control - No established association between HIV infection and Reye's syndrome *Measles virus* - While measles is an acute viral infection, the **documented association with Reye's syndrome is significantly weaker** compared to influenza and varicella - The major contraindication for aspirin in pediatric febrile illness specifically emphasizes **influenza and varicella** - Not considered one of the primary precipitating infections for Reye's syndrome

Q: A 4-year-old child presented with fever for 6 days, generalized rash and cervical lymphadenopathy with strawberry tongue. What could be the diagnosis?

Kawasaki disease. ***Kawasaki disease*** * Kawasaki disease is a **vasculitis** affecting medium-sized arteries, predominantly in children. * **Persistent fever** for more than 5 days, **generalized rash**, **cervical lymphadenopathy**, and **strawberry tongue** are key diagnostic criteria. * The child's age (4 years) is also consistent with the typical presentation of Kawasaki disease. *Kimura disease* * Kimura disease is a **rare chronic inflammatory condition** primarily affecting the head and neck, characterized by subcutaneous nodules and enlarged lymph nodes. * It typically presents with **painless subcutaneous masses**, often in young adults of Asian descent, and does not commonly include a generalized rash or strawberry tongue. *Scarlet fever* * Scarlet fever is caused by **Group A Streptococcus** and typically presents with a **fine, sandpaper-like rash**, **strawberry tongue**, and fever. * While a strawberry tongue and rash are present, the rash of Kawasaki disease is more polymorphous, and cervical lymphadenopathy is often more pronounced and less generalized than in scarlet fever. *Rosai Dorfman disease* * Rosai-Dorfman disease, also known as **sinus histiocytosis with massive lymphadenopathy**, is characterized by striking, often **painless and massive lymph node enlargement**, predominantly in the cervical region. * Systemic symptoms like fever and rash can occur, but the classic presentation does not typically include a "strawberry tongue" or the specific constellation of symptoms seen in Kawasaki disease.

Q: The following age group is most severely affected by Rubella infection -

Unborn child. ***Unborn child*** - Rubella infection during pregnancy, especially in the **first trimester**, can lead to **Congenital Rubella Syndrome (CRS)**, causing severe birth defects. - CRS can manifest as **cardiac malformations**, **cataracts**, **deafness**, and neurological disorders, making it the most severely affected group. *Young girls* - While susceptible to rubella, young girls typically experience a **mild, self-limiting disease** with a rash, low-grade fever, and lymphadenopathy. - The risk of severe complications as seen in CRS is significantly lower in this age group compared to an unborn child. *Adolescent girls* - Rubella infection in adolescent girls is generally a **mild illness**, similar to young girls, characterized by a rash and mild constitutional symptoms. - The main concern for this group is if they become pregnant, as **maternal infection** then poses a severe risk to the fetus, not the adolescent herself. *Females aged 25 -- 35 Year* - In this age group, rubella infection is typically **mild and self-limiting**, similar to younger females. - The primary concern is if the woman is pregnant or becomes pregnant, as the **teratogenic effects** on the fetus are devastating, not the severity of the disease in the mother.

Q: Most common organism causing bacterial meningitis between 6 months and 2 years in vaccinated populations.

Pneumococcus. ***Pneumococcus*** - **Pneumococcus (Streptococcus pneumoniae)** is now the most common cause of bacterial meningitis in children aged 6 months to 2 years in countries with high vaccination rates for *H. influenzae type b (Hib)* and *N. meningitidis*. - The introduction of the **pneumococcal conjugate vaccine (PCV)** has significantly reduced the incidence of pneumococcal meningitis, but it still remains the leading cause among the remaining cases in this age group. *E. coli* - **E. coli meningitis** is primarily a concern in **neonates** (birth to 1 month of age), often acquired during passage through the birth canal. - Its incidence significantly decreases after the neonatal period, making it a much less common cause in children aged 6 months to 2 years. *H. influenzae* - Before routine vaccination, **Haemophilus influenzae type b (Hib)** was the leading cause of bacterial meningitis in children under 5 years old. - The widespread use of the **Hib vaccine** has drastically reduced its incidence, making it a rare cause in vaccinated populations. *N. meningitidis* - **Neisseria meningitidis** (meningococcus) is a significant cause of bacterial meningitis, especially in older children, adolescents, and young adults. - While it can occur in children aged 6 months to 2 years, widespread **meningococcal vaccination** in many regions has reduced its overall prevalence, making *Pneumococcus* a more frequent cause in this specific vaccinated age group.

Q: Oral Thrush develops in infants at

2-6 weeks. **2-6 weeks (Correct)** - **Oral thrush** commonly appears in infants between **2 to 6 weeks of age**, as their immune systems are still developing and they are exposed to *Candida albicans* during birth or from their environment. - This period aligns with the typical onset of symptoms like **white patches** on the tongue and buccal mucosa, which cannot be easily wiped away. - This is the **most common age** for initial presentation of oral thrush in otherwise healthy infants. *18 months (Incorrect)* - While toddlers can get **oral thrush**, it's less common for the initial development to occur as late as **18 months** in an otherwise healthy child. - By this age, the infant's immune system is generally more robust, making primary oral thrush less likely unless there are predisposing factors like antibiotic use or immunodeficiency. *6 days (Incorrect)* - **Oral thrush** can sometimes manifest in the first few days of life, particularly with **birth canal transmission** of *Candida*. - While possible, the classic full-blown presentation is more common at **2-6 weeks** when maternal antibody protection begins to wane. *10-12 weeks (Incorrect)* - Though still possible, **oral thrush** is less typical to first develop around **10-12 weeks** in healthy infants. - If it appears at this age, it might suggest ongoing exposure, recurrence, or other contributing factors rather than the most common timeframe for initial presentation.

Q: Which of the following methods is NOT recommended for the diagnosis of HIV infection in a 2-month-old child?

HIV ELISA. ***HIV ELISA*** - **HIV ELISA** (Enzyme-linked Immunosorbent Assay) detects **HIV antibodies**, which are maternally derived and can persist in newborns for up to 18 months, leading to **false positive** results. - Therefore, antibody-based tests are **not suitable** for diagnosing HIV infection in infants under 18 months of age. *Viral culture* - **HIV viral culture** can directly detect the presence of replication-competent virus in an infant's blood. - While sensitive, it is **expensive**, labor-intensive, and takes a long time (several weeks) to obtain results, making it less practical for routine diagnosis. *DNA-PCR* - **DNA PCR (Polymerase Chain Reaction)** directly detects **HIV proviral DNA** within infected cells, making it highly specific and sensitive for early infant diagnosis. - It is currently the **recommended method** for HIV diagnosis in infants and young children, especially in the first few months of life. *P24 antigen assay* - The **P24 antigen assay** detects the **core protein of the HIV virus**, indicating active viral replication. - It can be used for early diagnosis in infants but may be less sensitive than DNA PCR, particularly in the presence of maternal antibodies or during early infection.

Q: 3 year old sister of a neonate is suffering from pertussis, which has been documented by isolation and culture of the organism. The mother received the pertussis vaccine during pregnancy. Most appropriate statement regarding this clinical situation is -

Azithromycin prophylaxis is indicated in the neonate. ***Azithromycin prophylaxis is indicated in the neonate*** - Neonates are highly vulnerable to **severe pertussis**, which can be life-threatening, making **post-exposure prophylaxis** crucial. - **Azithromycin** is the preferred macrolide antibiotic for pertussis prophylaxis and treatment in neonates, as it has better tolerability and a shorter treatment course compared to erythromycin. - **Erythromycin** carries a risk of infantile hypertrophic pyloric stenosis in infants <1 month old, making azithromycin the safer choice. *DPT vaccine is recommended for the elder child* - The 3-year-old already has pertussis, so vaccination at this point would not alter the course of her current illness, as the vaccine's purpose is **prevention**, not treatment. - While DPT vaccination is generally recommended for children, it's not the correct immediate action for a child actively suffering from **documented pertussis**. *Hyperimmune globulin is indicated for the neonate* - **Pertussis immune globulin** is not routinely recommended for pertussis prophylaxis or treatment due to insufficient evidence of its efficacy. - **Antibiotic prophylaxis** with a macrolide is the standard of care for exposed susceptible individuals, especially neonates. *The neonate is protected due to maternal vaccination* - While maternal pertussis vaccination during pregnancy does confer some **passive immunity** to the neonate, it might not offer complete protection, especially against close exposure to an infected sibling. - Given the severe risk of pertussis in neonates, **antibiotic prophylaxis** is still recommended as an extra layer of protection even with maternal antibodies.

Q: Resistant plasmodium falciparum malaria in the pediatric age group should be treated with -

Artemether-lumefantrine. ***Artemether-lumefantrine*** - **Artemether-lumefantrine** (Coartem) is the **WHO-recommended first-line treatment** for uncomplicated *P. falciparum* malaria, including **drug-resistant strains** (chloroquine-resistant, sulfadoxine-pyrimethamine resistant) - It is an **artemisinin-based combination therapy (ACT)** that is highly effective and **safe in pediatric patients** of all age groups, including infants ≥5 kg - The combination provides rapid parasite clearance (artemether) and eliminates residual parasites (lumefantrine), preventing resistance development - **ACTs remain the gold standard** for resistant P. falciparum malaria in children *Clindamycin* - **Clindamycin is NEVER used as monotherapy** for malaria due to its slow onset of action - It is used **only in combination with quinine or artesunate** for treatment of resistant or severe P. falciparum malaria when other options are unavailable - While safe in children, it is not a first-line agent and requires combination therapy *Tetracycline* - **Tetracycline** can be effective for malaria but is **absolutely contraindicated in children under 8 years** due to risk of permanent **tooth discoloration** (yellow-brown staining) and inhibition of bone growth - Therefore, it is unsuitable for the pediatric age group *Doxycycline* - **Doxycycline** is effective for malaria prophylaxis and treatment of resistant *P. falciparum* - However, like tetracycline, it is **contraindicated in children under 8 years** due to **dental staining** and skeletal development effects - Not appropriate for pediatric use in this age range

Q: Congenital rubella syndrome is associated with:

All of the options. ***All of the options*** - Congenital rubella syndrome (CRS) is well-known for causing a triad of **birth defects** affecting the heart, eyes, and ears, often referred to as **Gregg's triad**. - Exposure to the rubella virus during early pregnancy can lead to a range of severe and permanent anomalies in the developing fetus. *Congenital heart disease* - Common cardiac abnormalities associated with CRS include **patent ductus arteriosus (PDA)**, pulmonary artery stenosis, and ventricular septal defects (VSDs). - These defects arise from the virus interfering with the normal development of the **fetal heart** during the first trimester. *Sensorineural hearing loss* - This is one of the most common and often the **only manifestation** of CRS, leading to significant impairment. - The rubella virus can directly damage the **inner ear structures**, particularly the cochlea, resulting in permanent hearing loss. *Cataract* - Ocular defects such as **cataracts** (clouding of the lens), microphthalmia (small eyes), and glaucoma are characteristic features of CRS. - These conditions are due to the virus disrupting the normal development of the **fetal eye**, especially when infection occurs in the first 8 weeks of gestation.

Question 1

Reye's syndrome in children is commonly associated with aspirin use during which type of infection?

Accepted Answer

Influenza virus

Answer

Varicella (Chickenpox)

Answer

HIV

Answer

Measles virus

Question 2

A 4-year-old child presented with fever for 6 days, generalized rash and cervical lymphadenopathy with strawberry tongue. What could be the diagnosis?

Accepted Answer

Kawasaki disease

Answer

Kimura disease

Answer

Scarlet fever

Answer

Rosai-Dorfman disease

Question 3

The following age group is most severely affected by Rubella infection -

Accepted Answer

Unborn child

Answer

Young girls

Answer

Adolescent girls

Answer

Females aged 25-35 years

Question 4

Most common organism causing bacterial meningitis between 6 months and 2 years in vaccinated populations.

Accepted Answer

Pneumococcus

Answer

E. coli

Answer

H. influenzae

Answer

N. meningitidis

Question 5

Prophylaxis with Cotrimoxazole is recommended in the following situation EXCEPT:

Accepted Answer

Should be started only after the diagnosis of HIV is confirmed

Answer

All symptomatic HIV infected children > 5 years of age irrespective of CD4

Answer

All HIV infected infants less than 1 year age irrespective of symptoms or CD4 counts

Answer

All HIV exposed infants till HIV infection can be ruled out

Question 6

Oral Thrush develops in infants at

Accepted Answer

2-6 weeks

Answer

18 months

Answer

6 days

Answer

10-12 weeks

Question 7

Which of the following methods is NOT recommended for the diagnosis of HIV infection in a 2-month-old child?

Accepted Answer

HIV ELISA

Answer

Viral culture

Answer

DNA-PCR

Answer

P24 antigen assay

Question 8

3 year old sister of a neonate is suffering from pertussis, which has been documented by isolation and culture of the organism. The mother received the pertussis vaccine during pregnancy. Most appropriate statement regarding this clinical situation is -

Accepted Answer

Azithromycin prophylaxis is indicated in the neonate

Answer

DPT vaccine is recommended for the elder child

Answer

Hyperimmune globulin is indicated for the neonate

Answer

The neonate is protected due to maternal vaccination

Question 9

Resistant plasmodium falciparum malaria in the pediatric age group should be treated with -

Accepted Answer

Artemether-lumefantrine

Answer

Tetracycline

Answer

Clindamycin

Answer

Doxycycline

Question 10

Congenital rubella syndrome is associated with:

Accepted Answer

All of the options

Answer

Congenital heart disease

Answer

Sensorineural hearing loss

Answer

Cataract

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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