Infectious Diseases Practice Questions

Q: What is the most common presentation of AIDS in infants?

GI infection. ***GI infection*** - **Chronic diarrhea** and gastrointestinal infections are among the most common presentations of AIDS in infants, often leading to **failure to thrive** and malabsorption. - Infants frequently present with **persistent diarrhea** lasting more than 2 weeks, which is a common AIDS-defining illness in pediatric populations. - **Malnutrition** and poor weight gain secondary to GI manifestations are hallmark features of pediatric AIDS presentation. - Common pathogens include **Cryptosporidium**, **Salmonella**, **Cytomegalovirus**, and other opportunistic organisms. *Lymphadenopathy* - While **generalized lymphadenopathy** can occur in HIV-infected children, it is more commonly seen in older children and adults rather than as the primary presentation in infants. - It indicates immune system activation but is not the most frequent initial manifestation in the infant population. *Rashes* - Various **dermatological manifestations** such as seborrheic dermatitis, persistent candidiasis, and recurrent skin infections can occur in pediatric AIDS. - However, these are less common than gastrointestinal manifestations as the initial presentation in infants. *Persistent cough* - **Respiratory infections** including *Pneumocystis jirovecii* pneumonia (**PCP**) are serious and common opportunistic infections in infants with AIDS. - PCP is the most common serious opportunistic infection in pediatric AIDS, but chronic diarrhea and GI problems present more frequently overall as initial manifestations. - Other respiratory infections like recurrent pneumonia and lymphoid interstitial pneumonitis are also seen.

Q: Pertussis most severely affects which age group?

<5. **<5** - Pertussis, or **whooping cough**, is most severe and common in **infants and young children** who have not yet completed their primary vaccination series. - Children under **five years of age** are particularly vulnerable to severe complications such as pneumonia, seizures, and encephalopathy. *2–3* - While children in this age group can certainly contract pertussis, the peak incidence and severity are generally observed in **younger infants**. - This option is too restrictive as it excludes infants under 2 years who are at high risk. *5–7* - At this age, most children would have received their primary series of pertussis vaccinations, making severe infection **less common**. - Though breakthrough infections can occur, the age group under 5 years is still at higher risk for severe outcomes. *> 10 years* - Adults and older children can get pertussis, but their symptoms are often **milder** and less typical than in infants. - The question asks which age group pertussis affects, implying where it causes the most significant disease, which is not typically in those over 10 years.

Q: True about Measles rash appearance:

1-2 days after Koplik spots. ***1-2 days after Koplik spots*** - The characteristic **maculopapular rash** of measles typically appears on the **face and behind the ears** about 1-2 days after the onset of Koplik spots. - The rash then spreads **cephalocaudally** (from head to toe) over the next few days. *Along with Koplik spots* - **Koplik spots** are *pathognomonic* for measles and appear on the **buccal mucosa** *before* the rash. - They represent an enanthem, while the rash is an **exanthem**, and they do not appear simultaneously. *Post measles stage* - The post-measles stage is characterized by the fading of the rash, which desquamates, and the patient's recovery. - The rash is a defining feature of the active measles infection and does not appear in the post-measles stage. *1-2 days before Koplik spots* - Koplik spots are among the earliest clinical signs of measles, appearing 1-2 days *before* the skin rash. - The rash does not precede the Koplik spots; rather, it follows their appearance.

Q: A child with a fever of 102°F and vesicles in the oral cavity is probably suffering from:

Acute herpetic gingivostomatitis. ***Acute herpetic gingivostomatitis*** - This condition is caused by **Herpes simplex virus (HSV-1)** and typically presents in young children with a **high fever**, malaise, and characteristic **vesicular lesions** in the oral cavity that quickly rupture to form painful ulcers. - The combination of **fever** and widespread **oral vesicles** strongly indicates acute herpetic gingivostomatitis. *Herpes simplex type-I* - While HSV-1 is the **etiologic agent** for acute herpetic gingivostomatitis, simply stating "Herpes simplex type-I" as the diagnosis is less specific than the clinical presentation. - HSV-1 can cause various oral conditions, but the described symptoms are best captured by the more specific diagnosis of **acute herpetic gingivostomatitis**. *Neutropenia* - **Neutropenia** is a reduction in neutrophils, which can lead to increased susceptibility to infections and oral ulcers, but it does not directly cause the characteristic **vesicular lesions** described. - The primary presentation would be recurrent severe infections, not necessarily acute fever with widespread oral vesicles. *Juvenile periodontitis* - **Juvenile periodontitis** (now often termed aggressive periodontitis) is a localized form of periodontal disease characterized by rapid **attachment loss** and **bone destruction** around permanent teeth in otherwise healthy adolescents. - It does not present with acute fever and vesicular lesions in the oral cavity.

Q: Which vaccine is contraindicated in a child with an uncontrolled progressive neurological disorder?

DPT. ***DPT*** - The **pertussis component** of the DPT vaccine has a **contraindication** in children with **progressive or uncontrolled neurological disorders**, including **uncontrolled epilepsy** or **progressive encephalopathy**. - This is because any subsequent neurological event might be incorrectly attributed to the vaccine, and the risk-benefit ratio is unfavorable in unstable neurological conditions. - **Important distinction**: A history of **resolved febrile seizures** or **well-controlled epilepsy** is **NOT a contraindication** for pertussis-containing vaccines as per current IAP and WHO guidelines. - In cases of **progressive neurological disorders**, DPT is deferred until the condition stabilizes. *Typhoid* - **Typhoid vaccines** (both live attenuated Ty21a and inactivated Vi polysaccharide) have no neurological contraindications. - Primary contraindications relate to **immunosuppression** (for live vaccine) or **severe allergic reactions** to previous doses. *Measles* - The **measles vaccine (MMR)** is **not contraindicated** in children with neurological disorders or seizure history. - Even children with **uncontrolled epilepsy** can receive MMR vaccine, as the risk from **natural measles infection** (which causes encephalitis in 1:1000 cases) far exceeds any theoretical vaccine risk. - Post-vaccination fever and febrile seizures can occur but are much less common and severe than complications from measles disease. *BCG* - The **BCG vaccine** has **no neurological contraindications** whatsoever. - Main contraindications are **immunodeficiency states**, **active tuberculosis**, and **generalized septic skin conditions**.

Q: All of the following are true about erythema infectiosum EXCEPT?

Rash initially appears on trunk. ***Rash initially appears on trunk*** - Erythema infectiosum (fifth disease) characteristically begins with a **'slapped cheek' rash** on the face. - The rash then spreads to the trunk and extremities, taking on a **lacy, reticulated appearance**, but it does not initially appear on the trunk. *Caused by parvovirus* - Erythema infectiosum is caused by **Parvovirus B19**, which primarily infects erythroid progenitor cells. - This virus is highly contagious and spreads via respiratory secretions. *Known as 'fifth disease'* - Erythema infectiosum is one of the classic childhood exanthems and is historically known as **'fifth disease'**. - The numbering sequence refers to the order in which these common childhood rashes were identified. *Slapped cheek appearance seen* - A prominent feature of erythema infectiosum is the classic bright red rash on the cheeks, giving the child a distinctive **'slapped cheek' appearance**. - This facial rash often precedes the lacy rash on the body.

Q: True about measles

Long term complication follows in form of SSPE. ***Long term complication follows in form of SSPE*** - **Subacute sclerosing panencephalitis (SSPE)** is a rare, but fatal, progressive neurodegenerative disease that can develop years after a measles infection [1]. - It is caused by persistent measles virus in the brain, leading to **neurological deterioration** and eventually death [2]. *Rash appear first on leg* - The characteristic rash of measles typically appears first on the **face and behind the ears**, then spreads downward to the trunk and extremities [1]. - The rash is usually **maculopapular** and confluent, turning brownish and fading in the same order it appeared [1]. *Koplik spots are seen in retina* - **Koplik spots** are pathognomonic for measles and are found on the **buccal mucosa** (inside the cheeks), opposite the molars [1]. - They appear as small, white, or bluish-white spots with an erythematous base before the onset of the rash. *Caused by DNA virus* - Measles is caused by the **measles virus**, which is a **single-stranded RNA virus** belonging to the genus *Morbillivirus* in the family *Paramyxoviridae*. - It is not a DNA virus; this classification has significant implications for its replication cycle and vaccine development.

Q: In early congenital syphilis, which is not seen?

Keratitis. ***Keratitis*** - **Keratitis** (inflammation of the cornea) is a manifestation of **late congenital syphilis**, typically appearing in children older than 2 years. - It is often associated with other features of **Hutchinson's triad**, which includes **Hutchinson's teeth** and **sensorineural hearing loss**. *Vesicular rash* - A **maculopapular rash**, which can sometimes be vesicular or bullous, is a common finding in **early congenital syphilis**, particularly on the palms and soles. - This rash is a sign of active infection and can be highly infectious due to the presence of **spirochetes**. *Chorioretinitis* - **Chorioretinitis** (inflammation of the choroid and retina) is an important ocular manifestation of **early congenital syphilis**. - It can lead to significant vision impairment if not promptly diagnosed and treated. *Rhinitis* - Known as **"snuffles,"** rhinitis is a classic and common symptom of **early congenital syphilis**, often presenting with mucopurulent or hemorrhagic nasal discharge. - The nasal discharge contains infectious **Treponema pallidum** and can cause significant respiratory distress in infants.

Q: Which of the following is the most common late toxic manifestation of diphtheria in a child?

Polyneuritis. ***Polyneuritis*** - **Polyneuritis** is the **most common late toxic manifestation** of diphtheria, typically appearing **2-6 weeks or more** after the onset of infection. - It results from the **diphtheria toxin's neurotoxic effects**, causing demyelination of peripheral nerves. - Clinical features include **cranial nerve palsies** (especially palatal and pharyngeal weakness), **limb weakness**, and **areflexia**. - It can persist for weeks to months and is the characteristic delayed complication. *Renal failure* - While diphtheria toxin can cause **acute tubular necrosis**, renal failure is **uncommon** and not a primary late toxic manifestation. - When kidney injury occurs, it is typically mild and occurs earlier in the acute phase rather than as a delayed complication. *Myocarditis* - **Myocarditis** is a serious complication of diphtheria occurring in **10-25% of cases**, typically appearing in **weeks 2-6**. - While it overlaps with the timing of late manifestations, it generally presents **earlier in that window** (often weeks 2-3) compared to polyneuritis. - It is a **major cause of mortality** in diphtheria, but **polyneuritis is more common as a late manifestation** presenting after week 3-4. - Clinical features include arrhythmias, heart failure, and conduction defects. *Septicemia* - **Septicemia** is not a direct toxic manifestation of *Corynebacterium diphtheriae*. - Diphtheria causes disease primarily through **localized infection and systemic toxin effects**, not through bloodstream invasion. - Secondary bacterial superinfection is possible but is not a characteristic manifestation of diphtheria toxicity.

Question 1

What is the most common presentation of AIDS in infants?

Accepted Answer

GI infection

Answer

Rashes

Answer

Lymphadenopathy

Answer

Persistent cough

Question 2

All of the following statements about congenital rubella are true except:

Accepted Answer

Increased risk of congenital malformation if infection occurs after 16 weeks

Answer

Most common anomalies are hearing and heart defects

Answer

IgM antibody is present at birth

Answer

IgG persists for more than 6 months

Question 3

Pertussis most severely affects which age group?

Accepted Answer

<5

Answer

2–3

Answer

5–7

Answer

> 10 years

Question 4

True about Measles rash appearance:

Accepted Answer

1-2 days after Koplik spots

Answer

Along with Koplik spots

Answer

Post measles stage

Answer

1-2 days before Koplik spots

Question 5

A child with a fever of 102°F and vesicles in the oral cavity is probably suffering from:

Accepted Answer

Acute herpetic gingivostomatitis

Answer

Herpes simplex type-I

Answer

Neutropenia

Answer

Juvenile periodontitis

Question 6

Which vaccine is contraindicated in a child with an uncontrolled progressive neurological disorder?

Accepted Answer

DPT

Answer

Typhoid

Answer

Measles

Answer

BCG

Question 7

All of the following are true about erythema infectiosum EXCEPT?

Accepted Answer

Rash initially appears on trunk

Answer

Caused by parvovirus

Answer

Known as 'fifth disease'

Answer

Slapped cheek appearance seen

Question 8

True about measles

Accepted Answer

Long term complication follows in form of SSPE

Answer

Rash appear first on leg

Answer

Koplik spots are seen in retina

Answer

Caused by DNA virus

Question 9

In early congenital syphilis, which is not seen?

Accepted Answer

Keratitis

Answer

Vesicular rash

Answer

Chorioretinitis

Answer

Rhinitis

Question 10

Which of the following is the most common late toxic manifestation of diphtheria in a child?

Accepted Answer

Polyneuritis

Answer

Renal failure

Answer

Myocarditis

Answer

Septicemia

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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