Infectious Diseases Practice Questions

Q: A 7-year-old child with a history of ear infection is complaining of lockjaw and limb spasm/fever/neck rigidity. Choose the most appropriate diagnosis:

Tetanus. ***Tetanus*** - The striking combination of **lockjaw (trismus)** and generalized **limb spasms** is the hallmark clinical presentation of **Tetanus**, caused by the neurotoxin from *Clostridium tetani*. - The presence of **fever** and **neck rigidity** alongside an antecedent **ear infection** (potential portal of entry) strongly supports this diagnosis. - Tetanus causes sustained muscle contractions due to the inhibition of inhibitory neurons, leading to characteristic trismus, risus sardonicus, and opisthotonus. - Note: This is distinct from metabolic **tetany** (hypocalcemia), which causes carpopedal spasm without fever or lockjaw. *Incorrect: Meningitis* - While meningitis causes **fever** and **neck rigidity** (nuchal rigidity), it does not typically present with severe **lockjaw (trismus)** or sustained generalized **muscle spasms**. - Meningitis usually presents with headache, photophobia, altered consciousness, and positive Kernig's/Brudzinski's signs. *Incorrect: Bezold abscess* - A Bezold abscess is a deep neck abscess complicating mastoiditis, causing localized symptoms like neck pain, swelling, and **torticollis** (fixed head tilt). - It does not cause neuromuscular hyperexcitability resulting in **lockjaw** and widespread **limb spasms**. *Incorrect: Sinus thrombosis* - Lateral sinus thrombosis is a complication of otitis media presenting with **picket-fence fever**, headache, and signs of raised intracranial pressure. - It does not cause the characteristic muscle spasms and lockjaw seen in this presentation.

Q: An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Nevirapine + Zidovudine for 6 weeks. ***Nevirapine + Zidovudine for 6 weeks*** - This combination is the recommended regimen for **high-risk newborns** in resource-limited settings, defined by a maternal viral load (MVL) greater than 1000 copies/mL or if maternal treatment was **suboptimal/absent**. - The dual prophylaxis provides comprehensive coverage to minimize the risk of **mother-to-child transmission (MTCT)**, which is elevated due to the high viral load (1200 copies/mL). *Nevirapine for 6 weeks* - **Nevirapine monotherapy** is reserved for **low-risk newborns** (MVL < 1000 copies/mL) or when the mother received adequate **antiretroviral therapy (ART)**. - Given the MVL of 1200 copies/mL, the risk is high, making dual therapy necessary. *Nevirapine for 12 weeks* - Extended NVP prophylaxis (12 weeks) is sometimes used if the infant is **breastfed and at high risk**, but current standard guidelines for non-breastfed infants with this MVL recommend 6 weeks of dual therapy. - **Duration of 12 weeks** is typically not the initial prophylaxis choice for a non-breastfed infant born to a mother with a high viral load. *Zidovudine for 4 weeks* - **Zidovudine monotherapy** for 4 weeks is considered inadequate given the mother's high viral load of **1200 copies/mL**. - This regimen (4 weeks of ZDV) is primarily reserved for **low-risk newborns** in settings where dual therapy is not feasible, or for term infants born to mothers with **fully suppressed viral loads** who received continuous ART.

Q: A 6-week-old child with tuberous sclerosis, and on vigabatrin has been brought for vaccination. Which of the following vaccine should be given?

A. ***Correct Option A (DTaP/Pentavalent Vaccine)*** - At **6 weeks of age**, the child is due for the first dose of **DPT (Diphtheria, Pertussis, Tetanus)** or Pentavalent vaccine as per the Indian National Immunization Schedule - **Tuberous sclerosis is NOT an immunocompromising condition** and does not contraindicate any routine vaccines - **Vigabatrin is NOT immunosuppressive** - it is an antiepileptic drug used specifically for infantile spasms in tuberous sclerosis and does not affect vaccine response or safety - All routine vaccines including inactivated and live vaccines can be safely administered to children with tuberous sclerosis on vigabatrin *Incorrect Option B (BCG Vaccine)* - BCG vaccine is administered **at birth** (or as early as possible in the neonatal period), not at 6 weeks of age - By 6 weeks, the child should have already received BCG - Even if BCG was delayed, tuberous sclerosis and vigabatrin are NOT contraindications for BCG vaccination - The misconception that these children are immunocompromised is incorrect *Incorrect Option C (Varicella/Live Vaccine)* - Varicella vaccine is not part of the routine immunization schedule at 6 weeks in India - It is typically given at 15 months of age or later - Even though it is a live vaccine, it would NOT be contraindicated in this child as tuberous sclerosis and vigabatrin do not cause immunosuppression *Incorrect Option D (Other Vaccine Formulation)* - This does not represent the standard vaccine indicated at 6 weeks of age - At 6 weeks, the priority is to administer the first dose of DPT/Pentavalent vaccine along with OPV/IPV, Hepatitis B, Hib, Rotavirus, and PCV as per the immunization schedule

Q: A child presents with the ocular findings shown in the image below. Identify the most likely underlying illness:

Pertussis. ***Pertussis (Whooping Cough)*** - The image shows **subconjunctival hemorrhage**, which is a **classic complication** of pertussis in children - Pertussis causes severe **paroxysmal coughing fits** that dramatically increase intrathoracic and intravascular pressure - This elevated pressure leads to rupture of conjunctival blood vessels, resulting in subconjunctival hemorrhages and facial petechiae - These hemorrhages are well-recognized **diagnostic clues** for pertussis, especially when accompanied by the characteristic whooping cough - This is a **primary manifestation** of the disease process, not merely an incidental finding *Trachoma* - Trachoma, caused by *Chlamydia trachomatis*, presents with **chronic follicular conjunctivitis** and progressive scarring - Classic features include follicles on upper tarsal conjunctiva, conjunctival scarring, trichiasis, and pannus formation - While it causes conjunctival inflammation, **acute subconjunctival hemorrhage is NOT a typical feature** of trachoma - Trachoma is a chronic, scarring disease rather than an acute hemorrhagic condition *Tetanus* - Tetanus is a neurological disorder characterized by **muscle rigidity** and **spasms**, beginning with trismus (lockjaw) - Ocular manifestations are limited to **risus sardonicus** (facial muscle spasm) and potential ophthalmoplegia - Does NOT cause subconjunctival hemorrhage as a direct manifestation *Measles* - Measles presents with **maculopapular rash**, fever, the three C's (cough, coryza, conjunctivitis), and **Koplik spots** - The conjunctivitis in measles is typically a **bilateral, non-hemorrhagic inflammation** with watery discharge - Does NOT typically cause prominent subconjunctival hemorrhage as shown in the image

Q: Identify the cause of rash in the child:

Rubeola. ***Rubeola (Measles)*** - The image displays a **maculopapular rash**, which is characteristic of rubeola, commonly known as measles. The rash starts on the **face/behind the ears** and spreads downwards. - Measles rash is typically **blotchy** and can coalesce, and its distribution behind the ear is a classic early sign. *Rubella (German Measles)* - Rubella rash tends to be **finer** and **less confluent** than measles, often described as "rose-pink" macules. - While it also starts on the face and spreads, the rash is generally **milder** and disappears faster. *Varicella (Chickenpox)* - Varicella rash consists of **vesicles on an erythematous base** (dewdrop on a rose petal appearance), which then crust over. - The lesions appear in **crops**, leading to lesions of different stages simultaneously, which is not seen in the provided image. *Roseola infantum (Exanthem subitum)* - Roseola is characterized by a high fever for several days, followed by the sudden appearance of a **macular or maculopapular rash** once the fever breaks. - The rash typically starts on the **trunk** and spreads to the neck and extremities, which is a different pattern from the rash shown.

Q: Which is the most common complication of this rash?

Secondary skin infections. ***Secondary skin infections*** - The rash shows vesicles and pustules characteristic of **varicella (chickenpox)**. The lesions are intensely itchy, leading to scratching, which can break the skin barrier and introduce bacteria. - **Superinfection with *Staphylococcus aureus* or *Streptococcus pyogenes*** is the most common complication, resulting in impetigo, cellulitis, or even more severe invasive infections. *Otitis media* - While otitis media can occur during viral illnesses, it is not the most common complication and is generally less frequent than secondary skin infections in the context of **varicella**. - It arises from inflammation and fluid accumulation in the middle ear, often due to bacterial superinfection following viral upper respiratory tract infection, but not directly from the skin lesions. *Bronchopneumonia* - **Varicella pneumonia** can be a severe complication, especially in adults and immunocompromised individuals, but it is less common in healthy children than secondary skin infections. - Bronchopneumonia refers to widespread inflammation of the bronchi and bronchioles, often presenting with cough and respiratory distress. *Reye syndrome* - Reye syndrome is a rare but serious complication, primarily associated with **aspirin use** in children with viral infections like varicella or influenza. - It involves **acute encephalopathy** and **fatty liver degeneration**, but it is preventable by avoiding salicylates and is not a direct result of the rash itself.

Q: A 5-year-old child in a village went for open air defecation when he was attacked by a dog. He has been admitted in your hospital, all are correct about the condition except: (Recent NEET Pattern 2016-17)

Virus infects pyramidal cells leading to cytolysis. ***Virus infects pyramidal cells leading to cytolysis*** - The **rabies virus** primarily infects neurons and causes neuronal dysfunction rather than **cytolysis** (cell death and lysis), particularly in the early stages. - The characteristic pathological finding in rabies is the presence of **Negri bodies** (intracytoplasmic inclusions) which represent viral aggregates within unaffected neurons, not cytolytic destruction. *Category 3 bite* - A **Category 3 bite** involves single or multiple transdermal bites or scratches, licks on broken skin, or contamination of mucous membranes with saliva, especially if involving the head, neck, or digits, which appears to be the case given the severe facial injuries depicted with a dog bite. - Due to the high risk of rabies transmission in such severe wounds, Category 3 requires both **rabies vaccine** and **rabies immunoglobulin (RIG)** administration. *Wash with povidone-iodine* - Immediate and thorough **wound washing** with soap and water for at least 15 minutes is crucial for all animal bites, as it significantly reduces the viral load. - **Antiseptics** like povidone-iodine or alcohol can be used after washing to further disinfect the wound. *Administer vero cell vaccine with immunoglobulin* - For a **Category 3 rabies exposure**, both **rabies vaccine** (e.g., Vero cell vaccine) and **rabies immunoglobulin (RIG)** are indicated for post-exposure prophylaxis. - The vaccine provides active immunity, while the immunoglobulin provides immediate passive immunity, critical for high-risk exposures.

Q: A 6-year-old child from Kashmir is brought to New Delhi hospital in delirious condition with history of high grade fever for last 10 days. He is nonresponsive to commands and blanching rash is noted all over the body especially soles and palms. Per abdomen examination shows splenohepatomegaly. Blood culture was sterile after 48 hours of incubation, WeilFelix reaction shows increasing antibody titer and complement fixation test was positive. Which is the best treatment for the patient?

Doxycycline. ***Doxycycline*** - The clinical presentation (high-grade fever, delirium, blanching rash on soles and palms, splenohepatomegaly, sterile blood culture, positive Weil-Felix) is highly suggestive of **scrub typhus**, a rickettsial infection. - **Doxycycline** is the treatment of choice for rickettsial infections, including scrub typhus, across all age groups, given its superior efficacy and limited alternatives. *Amoxicillin clavulanic acid* - This antibiotic combination is effective against a broad spectrum of **bacterial infections**, but it is not effective against rickettsial organisms. - The presented symptoms and lab results (especially positive Weil-Felix and sterile blood culture for common bacteria) rule out typical bacterial infections treatable by amoxicillin-clavulanic acid. *Ciprofloxacin* - Ciprofloxacin is a **fluoroquinolone antibiotic** typically used for various bacterial infections, including some atypical bacteria. - While it has some activity against rickettsia, it is not considered the first-line treatment and is less effective than doxycycline for scrub typhus. *Rifabutin* - Rifabutin is an antibiotic primarily used for the treatment of **mycobacterial infections**, such as those caused by *Mycobacterium avium complex* (MAC) or tuberculosis. - It has no role in the treatment of rickettsial infections like scrub typhus.

Q: A 6-year-old child from Kashmir is brought to New Delhi hospital in a delirious condition with history of high grade fever for last 10 days. He is nonresponsive to commands and blanching rash is noted all over the body especially soles and palms. Per abdomen examination shows splenohepatomegaly. Probable diagnosis is:

Rickettsia. ***Rickettsia*** - The combination of **high-grade fever**, **delirium**, **non-blanching rash** on palms and soles, and **splenohepatomegaly** is highly suggestive of severe rickettsial infection, especially with the child being from Kashmir where rickettsial diseases like Indian Tick Typhus are endemic. - The **non-blanching rash** (petechial/purpuric) on palms and soles is a classic, though not universally present, sign of severe rickettsial infection, reflecting vascular damage. *Cerebral malaria* - While cerebral malaria can cause **delirium**, **high fever**, and **splenohepatomegaly**, it typically does not present with a prominent **blanching rash** on the palms and soles. - Malaria is often endemic in Kashmir, but the rash pattern described is less typical for it. *Dengue hemorrhagic fever* - Dengue hemorrhagic fever can cause high fever, rash, and in severe cases, neurological symptoms due to shock or encephalopathy. However, the rash is typically **maculopapular** or **petechial**, and while it can involve extremities, the prominent *blanching* nature and distribution solely on **palms and soles** are less characteristic. - While splenomegaly can occur, prominent **splenohepatomegaly** in conjunction with this specific rash and neurological status points away from uncomplicated or even severe dengue as the primary diagnosis. *SSPE* - **Subacute sclerosing panencephalitis (SSPE)** is a chronic, progressive, and fatal neurodegenerative disease that usually develops several years after measles infection. - It presents with progressive neurological deterioration, including **cognitive decline**, **myoclonus**, and **seizures**, but does not typically involve acute high fever or a rash like the one described.

Q: A 4-year-old child presents with fever for 4 days with decreased oral intake. On examination a rough textured rash on trunk is seen which blanches on pressure. Later the rash fades and desquamation occurs. All are true about the condition except:

Perioral cyanosis. ***Perioral cyanosis*** - **Perioral cyanosis** (bluish discoloration around the mouth) is *not* a characteristic feature of scarlet fever. It typically indicates **hypoxemia**, which is not directly caused by the streptococcal exotoxins in this condition. - Scarlet fever is characterized by a "circumoral pallor" where the area around the mouth appears pale in contrast to the flushed cheeks, rather than cyanotic. *Caused by streptococcal pyrogenic exotoxins A, B, and C* - Scarlet fever is indeed caused by strains of *Streptococcus pyogenes* that produce **streptococcal pyrogenic exotoxins (SPEs)**, particularly types A, B, and C. - These exotoxins act as **superantigens** and are responsible for the characteristic rash and systemic symptoms of scarlet fever. *Sandpaper rash* - The description of a **rough textured rash on the trunk that blanches on pressure**, fades, and then undergoes desquamation is characteristic of the **sandpaper rash** seen in scarlet fever. - This rash is a hallmark clinical sign of scarlet fever, caused by the erythrogenic toxins. *Red strawberry tongue* - The **red strawberry tongue** (initially white with red papillae, then becoming uniformly red) is a classic oral manifestation of scarlet fever. - This finding is due to the inflammation of the tongue papillae and is a key diagnostic feature of the condition.

Question 1

A 7-year-old child with a history of ear infection is complaining of lockjaw and limb spasm/fever/neck rigidity. Choose the most appropriate diagnosis:

Accepted Answer

Tetanus

Answer

Meningitis

Answer

Bezold abscess

Answer

Sinus thrombosis

Question 2

An HIV-positive mother with a viral load of 1200 copies/mL delivers a baby. What is the most appropriate antiretroviral prophylaxis for the newborn?

Accepted Answer

Nevirapine + Zidovudine for 6 weeks

Answer

Zidovudine for 4 weeks

Answer

Nevirapine for 6 weeks

Answer

Nevirapine for 12 weeks

Question 3

A 6-week-old child with tuberous sclerosis, and on vigabatrin has been brought for vaccination. Which of the following vaccine should be given?

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 4

A child presents with the ocular findings shown in the image below. Identify the most likely underlying illness:

Accepted Answer

Pertussis

Answer

Tetanus

Answer

Measles

Answer

Trachoma

Question 5

Identify the cause of rash in the child:

Accepted Answer

Rubeola

Answer

Rubella

Answer

Varicella

Answer

Roseola infantum

Question 6

Which is the most common complication of this rash?

Accepted Answer

Secondary skin infections

Answer

Otitis media

Answer

Bronchopneumonia

Answer

Reye syndrome

Question 7

A 5-year-old child in a village went for open air defecation when he was attacked by a dog. He has been admitted in your hospital, all are correct about the condition except: (Recent NEET Pattern 2016-17)

Accepted Answer

Virus infects pyramidal cells leading to cytolysis

Answer

Category 3 bite

Answer

Wash with povidone-iodine

Answer

Administer vero cell vaccine with immunoglobulin

Question 8

A 6-year-old child from Kashmir is brought to New Delhi hospital in delirious condition with history of high grade fever for last 10 days. He is nonresponsive to commands and blanching rash is noted all over the body especially soles and palms. Per abdomen examination shows splenohepatomegaly. Blood culture was sterile after 48 hours of incubation, WeilFelix reaction shows increasing antibody titer and complement fixation test was positive. Which is the best treatment for the patient?

Accepted Answer

Doxycycline

Answer

Amoxicillin clavulanic acid

Answer

Ciprofloxacin

Answer

Rifabutin

Question 9

A 6-year-old child from Kashmir is brought to New Delhi hospital in a delirious condition with history of high grade fever for last 10 days. He is nonresponsive to commands and blanching rash is noted all over the body especially soles and palms. Per abdomen examination shows splenohepatomegaly. Probable diagnosis is:

Accepted Answer

Rickettsia

Answer

Cerebral malaria

Answer

Dengue hemorrhagic fever

Answer

SSPE

Question 10

A 4-year-old child presents with fever for 4 days with decreased oral intake. On examination a rough textured rash on trunk is seen which blanches on pressure. Later the rash fades and desquamation occurs. All are true about the condition except:

Accepted Answer

Perioral cyanosis

Answer

Caused by streptococcal pyrogenic exotoxins A, B, and C

Answer

Sandpaper rash

Answer

Red strawberry tongue

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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