Infectious Diseases Practice Questions

Q: Which of the following is the most characteristic feature of the rash distribution in chickenpox?

More concentrated on the trunk than limbs. ***More concentrated on the trunk than limbs*** - The rash of chickenpox (varicella) has a **pathognomonic centripetal distribution**, meaning it is most dense on the **trunk, face, and scalp**, with fewer lesions on the extremities. - This characteristic distribution pattern is the **most distinguishing feature** of chickenpox and helps differentiate it from other vesicular exanthems. - References: Nelson Textbook of Pediatrics, Ghai Essential Pediatrics *Superficial and not deep-seated* - While chickenpox lesions are indeed **superficial vesicles** affecting the epidermis, this characteristic is less specific. - Many other viral exanthems also produce superficial lesions, making this a less distinguishing feature. *Affects palms and soles* - **Incorrect.** Chickenpox lesions characteristically **spare the palms and soles**. - Involvement of palms and soles suggests hand, foot, and mouth disease, secondary syphilis, or other conditions. *Evolves rapidly with new spots appearing in waves over days* - While true that chickenpox lesions appear in **crops over 3-5 days** creating the "**dewdrops on a rose petal**" appearance with lesions in various stages, this describes the **temporal evolution** rather than the **spatial distribution pattern**. - The question specifically asks about the most characteristic feature, and centripetal distribution is more pathognomonic than the cropping pattern.

Q: In which of the following conditions can strawberry tongue be observed?

Both conditions mentioned above. ***Both conditions mentioned above*** - **Strawberry tongue** is a characteristic finding in both **streptococcal scarlet fever** and **Kawasaki disease** [2]. - In both conditions, the tongue initially appears white with prominent red papillae, resembling a white strawberry, and later becomes bright red, described as a red strawberry [2]. *Streptococcal scarlet fever* - **Strawberry tongue** is a classic symptom of **scarlet fever**, which is caused by Group A Streptococcus infection [2]. - Other symptoms often include a **diffuse red rash**, sore throat, and fever [2]. *Kawasaki disease* - **Strawberry tongue** is one of the mucocutaneous manifestations of **Kawasaki disease**, a multisystem vasculitis primarily affecting young children [1]. - Other key features include **fever lasting ≥5 days**, conjunctival injection, rash, cervical lymphadenopathy, and extremity changes [1]. *None of the options* - This option is incorrect because **strawberry tongue** is indeed observed in both scarlet fever and Kawasaki disease [1], [2]. - The presence of this specific tongue appearance is a well-documented clinical sign in these two distinct conditions.

Q: A 3-month-old baby presents with deafness, cataract, and patent ductus arteriosus. Which of the following is the most likely diagnosis?

Congenital rubella syndrome. ***Congenital rubella syndrome*** - The classic triad of **deafness**, **cataracts**, and **patent ductus arteriosus (PDA)** is highly characteristic of congenital rubella syndrome. - This syndrome results from **maternal rubella infection** during the first trimester of pregnancy. *Congenital herpes simplex virus infection* - Typically presents with **skin vesicles**, **keratoconjunctivitis**, and **encephalitis**. - **Deafness, cataracts, and PDA** are not common features of congenital HSV. *Congenital toxoplasmosis* - The classic triad involves **chorioretinitis**, **hydrocephalus**, and **intracranial calcifications**. - While it can cause microcephaly and seizures, **deafness, cataracts, and PDA** are not hallmark features. *Congenital cytomegalovirus infection* - Often causes **sensorineural hearing loss** and sometimes **chorioretinitis**, but the combination with **cataracts** and **PDA** is atypical. - Other common features include **periventricular calcifications**, **hepatosplenomegaly**, and **thrombocytopenia**.

Q: What is the most serious complication of measles?

Pneumonia. ***Pneumonia*** - **Pneumonia**, particularly **giant cell pneumonia**, is the most common cause of **measles-related deaths** in young children. - It results from the **direct viral infection** of the lungs or a **secondary bacterial superinfection**. *Croup* - **Croup (laryngotracheobronchitis)** can be a complication of measles, but it is typically **less severe** and **less life-threatening** than pneumonia. - It primarily affects the **upper airways**, causing a barking cough and stridor. *Meningo-encephalitis* - **Meningo-encephalitis** is a serious, albeit **less common**, complication of measles, occurring in approximately 1 in 1,000 cases. - While potentially fatal or leading to neurological sequelae, it is **outranked by pneumonia** in terms of overall mortality attributed to measles. *Otitis media* - **Otitis media** (middle ear infection) is a common complication of measles, but it is generally **not life-threatening**. - It usually responds well to **antibiotic treatment** and rarely leads to severe outcomes.

Q: Which of the following statements regarding Pertussis is INCORRECT?

Cerebellar ataxia is a known complication.. ***Cerebellar ataxia is a known complication.*** - **Cerebellar ataxia** is not a typical or known complication of pertussis. Complications usually involve the respiratory, neurological (e.g., seizures, encephalopathy due to hypoxia), and nutritional systems due to severe coughing. - While neurological complications can occur, **ataxia** specifically is not frequently sighted in the context of pertussis. *Some infections may be subclinical.* - Some individuals, especially those partially immunized or older, can experience **subclinical or atypical infections** with pertussis, often presenting as a mild cough. - This characteristic makes it difficult to control the spread of the disease as infected individuals may not be recognized. *The most infective stage is the catarrhal stage.* - The **catarrhal stage**, characterized by non-specific cold-like symptoms, is the most contagious phase because bacterial shedding is highest. - During this stage, symptoms are mild and often indistinguishable from a common cold, leading to widespread transmission before diagnosis. *The drug of choice is Erythromycin.* - **Erythromycin**, or other macrolides like azithromycin or clarithromycin, are the drugs of choice for treating pertussis. - These antibiotics are most effective when administered early in the **catarrhal stage** to reduce disease severity and prevent transmission.

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

Failure to thrive. ***Failure to thrive*** - **Growth retardation** and **weight loss** in infants with AIDS are directly related to the chronic stress of the infection, recurrent infections, and malabsorption. - This symptom reflects the body's inability to maintain normal growth and development due to the underlying severe **immunosuppression**. *GI infection* - While **gastrointestinal infections** are common in infants with AIDS due to immune compromise, they are a consequence rather than the initial, most common presenting symptom. - They often contribute to, but are not synonymous with, the broader syndrome of **failure to thrive**. *Persistent cough* - A **persistent cough** can be a symptom of various opportunistic infections, such as *Pneumocystis jirovecii* pneumonia (PJP), which is common in infants with AIDS. - However, it is not the single most common *initial* symptom across all presentations of pediatric AIDS. *Lymphadenopathy* - **Lymphadenopathy** (swollen lymph nodes) is a very common sign of HIV infection in children due to chronic immune stimulation. - While prevalent, it is often a *physical finding* on examination rather than the primary symptom that parents typically notice leading to presentation, which is often related to the child's overall well-being and growth.

Q: A baby from a second degree consanguineous marriage presents with diarrhoea and redness in the perianal diaper area. What is the most likely diagnosis?

Fungal infection. ***Fungal infection (Candida diaper dermatitis)*** - **Diarrhea with perianal diaper rash** is the classic presentation of **Candida (fungal) diaper dermatitis**, the most common cause of diaper rash in infants with diarrhea. - **Diarrhea increases skin moisture and alters pH**, creating optimal conditions for **Candida albicans overgrowth**. - **Perianal involvement with bright erythema** is characteristic of Candida, often with **satellite lesions** and involvement of skin folds. - This is a **clinical diagnosis** based on distribution pattern and association with diarrhea; consanguinity is not directly relevant to this common condition. *Lactose intolerance* - **Congenital lactase deficiency** is extremely rare (< 50 cases worldwide) and unlikely to be the primary diagnosis. - While **secondary lactose intolerance** can occur with gastroenteritis causing diarrhea, it doesn't explain the **specific perianal rash pattern** described. - The perianal redness in lactose malabsorption would be **irritant contact dermatitis** from acidic stools, which would secondarily get infected with **Candida** - making fungal infection the more complete diagnosis. *Shigella infection* - Typically presents with **bloody diarrhea (dysentery)**, high fever, abdominal cramps, and tenesmus. - Would not specifically cause the **perianal diaper rash pattern** characteristic of Candida. - Consanguinity doesn't predispose to this bacterial infection. *Salmonella infection* - Usually presents with **fever, vomiting, and systemic symptoms** along with diarrhea. - May cause bloody or non-bloody diarrhea but doesn't explain the **characteristic perianal redness pattern**. - Not associated with consanguinity as it's an acquired infectious disease.

Q: Which of the following diseases is not effectively prevented by maternal antibodies transferred during pregnancy?

Whooping cough (Pertussis). ***Whooping cough (Pertussis)*** - **Maternal antibodies** against pertussis are **poorly transferred** across the placenta, offering **limited protection** to the neonate. - Infants remain highly vulnerable to pertussis, necessitating early vaccination or **cocooning strategies** (vaccinating close contacts). *Mumps* - Maternal antibodies provide **effective passive immunity** to the infant for several months, protecting against mumps. - This protection wanes, making **childhood vaccination (MMR)** crucial. *Rubella* - **Maternal antibodies** against rubella are **effectively transferred**, providing good protection to the infant during the first 6-12 months of life. - This is particularly important as congenital rubella syndrome can cause severe birth defects. *Measles* - Infants born to mothers with measles immunity receive **strong passive maternal antibody protection**, which typically lasts until 6-9 months of age. - This initial protection is why the first dose of the **MMR vaccine** is usually given around 12 months.

Q: Rubella is known to cause all of the following conditions except:

Glaucoma. ***Glaucoma*** - While rubella can cause **ocular defects** such as **cataracts** and **pigmentary retinopathy**, glaucoma is not a typical congenital manifestation of rubella syndrome. - **Congenital glaucoma** is more commonly associated with other genetic syndromes or developmental anomalies. *Microcephaly* - **Microcephaly** is a recognized neurological complication of congenital rubella syndrome, resulting from impaired brain development due to viral infection. - The rubella virus can interfere with the **proliferation and migration** of neuronal cells during fetal development. *VSD* - **Ventricular septal defect (VSD)** is a common congenital heart defect associated with congenital rubella syndrome. - Other cardiac anomalies seen include **patent ductus arteriosus (PDA)** and **pulmonary artery stenosis**. *Conduction defects* - **Conduction defects** and other **cardiac arrhythmias** can occur in congenital rubella syndrome due to direct viral damage to the developing cardiac conduction system. - This can manifest as **bradyarrhythmias** or various degrees of **heart block**.

Question 1

Which of the following is the most characteristic feature of the rash distribution in chickenpox?

Accepted Answer

More concentrated on the trunk than limbs

Answer

Superficial and not deep-seated

Answer

Affects palms and soles

Answer

Evolves rapidly with new spots appearing in waves over days.

Question 2

In which of the following conditions can strawberry tongue be observed?

Accepted Answer

Both conditions mentioned above

Answer

Streptococcal scarlet fever

Answer

Kawasaki disease

Answer

None of the options

Question 3

A 3-month-old baby presents with deafness, cataract, and patent ductus arteriosus. Which of the following is the most likely diagnosis?

Accepted Answer

Congenital rubella syndrome

Answer

Congenital herpes simplex virus infection

Answer

Congenital toxoplasmosis

Answer

Congenital cytomegalovirus infection

Question 4

What is the most serious complication of measles?

Accepted Answer

Pneumonia

Answer

Croup

Answer

Otitis media

Answer

Meningo-encephalitis

Question 5

Which of the following statements regarding Pertussis is INCORRECT?

Accepted Answer

Cerebellar ataxia is a known complication.

Answer

The drug of choice is Erythromycin.

Answer

Some infections may be subclinical.

Answer

The most infective stage is the catarrhal stage.

Question 6

What is the most common symptom of AIDS in infants?

Accepted Answer

Failure to thrive

Answer

Persistent cough

Answer

Lymphadenopathy

Answer

GI infection

Question 7

A baby from a second degree consanguineous marriage presents with diarrhoea and redness in the perianal diaper area. What is the most likely diagnosis?

Accepted Answer

Fungal infection

Answer

Shigella infection

Answer

Salmonella infection

Answer

Lactose intolerance

Question 8

Which of the following diseases is not effectively prevented by maternal antibodies transferred during pregnancy?

Accepted Answer

Whooping cough (Pertussis)

Answer

Mumps

Answer

Rubella

Answer

Measles

Question 9

Rubella is known to cause all of the following conditions except:

Accepted Answer

Glaucoma

Answer

Conduction defects

Answer

VSD

Answer

Microcephaly

Question 10

Prophylaxis with cotrimoxazole is recommended in all situations except for which of the following?

Accepted 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

Answer

As secondary prophylaxis after initial treatment for Pneumocystis jirovecii pneumonia

Infectious Diseases — MCQs

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