Infectious Diseases Practice Questions

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.

Q: Most common organism causing meningitis in a 1 year old child -

Streptococcus pneumoniae. ***Streptococcus pneumoniae*** - **_Streptococcus pneumoniae_** is currently the most prevalent cause of bacterial meningitis in children over **3 months of age**, including 1-year-olds, largely due to successful vaccination programs reducing other common pathogens. - Though **meningococcal disease** often presents with a fulminant course, **pneumococcal meningitis** is more frequently encountered among pathogens overall in this age group due to its widespread carriage and diverse serotypes. *Listeria* - **_Listeria monocytogenes_** is a significant cause of meningitis in **neonates** (under 1 month of age) and **immunocompromised individuals**, but less common in a healthy 1-year-old. - Transmission typically occurs vertically from mother to child or through contaminated food products. *H. influenzae* - **_Haemophilus influenzae_ type B (Hib)** was historically a major cause of meningitis in young children, but its incidence has dramatically decreased due to widespread **Hib vaccination**. - While other non-typeable strains or unvaccinated individuals can still be affected, it is no longer the most common cause in vaccinated populations. *Neisseria meningitidis* - **_Neisseria meningitidis_** is a significant cause of bacterial meningitis, particularly in children and young adults, often associated with epidemics and a **petechial rash**. - Although it can cause severe disease and outbreaks, **_Streptococcus pneumoniae_** tends to have a higher overall incidence in 1-year-olds in the post-Hib vaccine era.

Q: True about childhood tuberculosis:

Diagnosis by sputum is difficult. ***Diagnosis by sputum is difficult*** - Children often have **pauci-bacillary disease**, meaning fewer bacteria are present in their sputum, making microbiological confirmation challenging. - Young children typically **cannot produce adequate sputum samples** voluntarily, unlike adults. - **Gastric aspirates** or induced sputum may be needed, but even these have lower diagnostic yield. - This is a hallmark feature distinguishing pediatric TB from adult TB. *Highly contagious* - Childhood tuberculosis, especially **extrapulmonary forms** or **pauci-bacillary disease**, is generally considered **less contagious** than adult pulmonary TB. - The reduced bacterial load and less forceful cough in children make transmission less efficient. - Children are more commonly victims than vectors of TB transmission. *5% prevalence* - The global prevalence of tuberculosis in children is highly variable and depends on specific regional epidemiology. - This figure is not a generally accepted statistic for childhood TB prevalence. *Common in 5-8 years age* - While TB can occur at any age, **children under 5 years old** are at highest risk for **severe and disseminated disease** (including TB meningitis and miliary TB). - Older children and adolescents might have clinical presentations more akin to adult TB, but the 5-8 year age range is not specifically highlighted as the peak age for childhood TB.

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

Enterovirus. ***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 1

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 2

Oral Thrush develops in infants at

Accepted Answer

2-6 weeks

Answer

18 months

Answer

6 days

Answer

10-12 weeks

Question 3

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 4

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 5

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

Accepted Answer

Artemether-lumefantrine

Answer

Tetracycline

Answer

Clindamycin

Answer

Doxycycline

Question 6

Congenital rubella syndrome is associated with:

Accepted Answer

All of the options

Answer

Congenital heart disease

Answer

Sensorineural hearing loss

Answer

Cataract

Question 7

A 30 month old deaf boy whose development is slower than normal is being followed for congenital cytomegalovirus (CMV) infection in your clinic.The child's mother is pregnant again and is worried about her new baby. Which of the following is true?

Accepted Answer

The mother has antibodies to CMV that are passed to the fetus

Answer

The new infant should be isolated from the older child

Answer

Termination of pregnancy is advised

Answer

The mother's infection cannot become reactivated

Question 8

Most common organism causing meningitis in a 1 year old child -

Accepted Answer

Streptococcus pneumoniae

Answer

Listeria

Answer

H. influenzae

Answer

Neisseria meningitidis

Question 9

True about childhood tuberculosis:

Accepted Answer

Diagnosis by sputum is difficult

Answer

Highly contagious

Answer

5% prevalence

Answer

Common in 5-8 years age

Question 10

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

Accepted Answer

Enterovirus

Answer

Mumps

Answer

HSV

Answer

Arbovirus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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