Infectious Diseases Practice Questions

Q: Large bilateral painless effusions of the knees occurring in late congenital syphilis in patients between ages 8 to 18 are designated as?

Clutton's joints. **Explanation:** **Clutton’s joints** are a classic manifestation of **late congenital syphilis**, typically appearing between the ages of 8 and 18 years. The condition is characterized by symmetrical, painless swelling (hydrarthrosis) of the joints, most commonly involving the **knees**, though elbows and ankles may also be affected. The underlying pathology is a chronic synovitis with effusion. Despite the significant swelling, there is minimal pain, no redness, and the range of motion is usually preserved. **Analysis of Incorrect Options:** * **Ramsey’s joints:** This is a distractor; there is no recognized medical condition by this name in the context of syphilis or orthopedics. (Note: Not to be confused with Ramsay Hunt syndrome, which involves Herpes Zoster). * **Charcot’s joints (Neuropathic Arthropathy):** This refers to progressive joint destruction due to loss of pain sensation and proprioception. While associated with syphilis, it occurs in **Tertiary Syphilis (Tabes Dorsalis)** in adults, not late congenital syphilis in children. * **Mercer’s joints:** This is a distractor and not a recognized clinical entity in pediatric infectious diseases. **High-Yield Clinical Pearls for NEET-PG:** * **Hutchinson’s Triad:** A hallmark of late congenital syphilis consisting of: 1. Interstitial keratitis, 2. Sensorineural hearing loss (8th nerve deafness), and 3. Hutchinson’s teeth (notched incisors). * **Other Skeletal Signs:** Look for **Saber shins** (anterior bowing of the tibia) and **Higouménakis sign** (thickening of the medial end of the clavicle). * **Early vs. Late:** Clutton’s joints are a "Late" feature (occurring after age 2), whereas **Parrot’s Pseudoparalysis** (due to painful osteochondritis) is an "Early" feature seen in infants.

Q: Which of the following is true about roseola infantum?

Caused by HHV 6 and 7. ### Explanation **Roseola Infantum**, also known as **Exanthema Subitum** or Sixth Disease, is a common viral febrile illness of early childhood (typically 6–36 months of age). **1. Why Option B is Correct:** Roseola is primarily caused by **Human Herpesvirus 6 (HHV-6)**, and less frequently by **HHV-7**. These viruses are lymphotropic and remain latent in the body after primary infection. **2. Analysis of Incorrect Options:** * **Option A:** In Roseola, the classic clinical hallmark is that the **rash appears after defervescence** (the fever disappears). The child typically has a high-grade fever (often >40°C) for 3–5 days; as the fever abruptly drops, a maculopapular rash emerges. * **Option C:** A "slapped cheek" appearance is the characteristic rash of **Erythema Infectiosum** (Fifth Disease), caused by **Parvovirus B19**. * **Option D:** While otitis media can occur, the most common and high-yield complication associated with Roseola infantum is **Febrile Seizures**, occurring in approximately 10–15% of cases due to the rapid rise in temperature. **3. NEET-PG High-Yield Clinical Pearls:** * **Nagayama Spots:** Small erythematous papules on the soft palate and uvula (seen in some patients before the skin rash). * **Rash Characteristics:** The rash is typically rose-pink, non-pruritic, starts on the **trunk**, and spreads to the neck and extremities (centrifugal spread). * **Age Group:** Most common cause of a febrile rash in an infant under 2 years of age. * **Treatment:** Supportive (antipyretics); the disease is usually self-limiting.

Q: What is the treatment of varicella in an immunocompetent host?

Prevention of complications. ### **Explanation** The correct answer is **C. Prevention of complications**. **1. Why "Prevention of complications" is correct:** In an **immunocompetent host** (especially children), Varicella (Chickenpox) is typically a self-limiting disease. The primary goal of management is supportive care to prevent secondary bacterial infections (most commonly by *Staphylococcus aureus* or *Streptococcus pyogenes*) and other complications. This includes maintaining hygiene, trimming fingernails to prevent scratching, and using calamine lotion or antihistamines for pruritus. Antiviral therapy is generally not mandatory for healthy children as the benefit is marginal. **2. Why the other options are incorrect:** * **A. Acyclovir:** While Acyclovir can be used, it is **not routine** for all immunocompetent hosts. It is specifically indicated if the patient is >12 years old, has chronic cutaneous/pulmonary disorders, or is on long-term salicylate/steroid therapy. * **B. Acyclovir and vaccination:** Vaccination is a preventive measure (primary prophylaxis) and is not used as a treatment modality once the infection has manifested. * **C. Immunoglobulin (VZIG):** This is used for **post-exposure prophylaxis** in high-risk individuals (e.g., neonates, pregnant women, or immunocompromised patients) who have been exposed to the virus, not as standard treatment for an active infection in a healthy host. **3. Clinical Pearls for NEET-PG:** * **Tzanck Smear:** Shows **Multinucleated Giant Cells** (common to HSV and VZV). * **Dew-drop on a rose petal:** Classic description of the varicella vesicle on an erythematous base. * **Pleomorphism:** The hallmark of chickenpox where lesions in all stages (papules, vesicles, crusts) are seen simultaneously. * **Congenital Varicella Syndrome:** Highest risk if the mother is infected between **8–20 weeks** of gestation; characterized by limb hypoplasia and cicatricial skin scarring.

Q: What is the recommended treatment for an infant born to a mother with active tuberculosis?

Isoniazid prophylaxis. **Explanation:** The management of a neonate born to a mother with active tuberculosis (TB) focuses on preventing the high risk of primary infection and progression to disseminated disease (like TB meningitis) in the infant. **Why Option A is Correct:** According to the **National Tuberculosis Elimination Program (NTEP)** and WHO guidelines, if a mother has active pulmonary TB, the neonate should be started on **Isoniazid (INH) prophylaxis** at a dose of **5 mg/kg/day for 6 months**. This is because the infant is considered a "high-risk contact." BCG vaccination should be deferred until the completion of the 6-month INH course. After 6 months, if the infant is asymptomatic and the Mantoux test/Chest X-ray is negative, INH is stopped and BCG is administered. **Why Other Options are Incorrect:** * **Option B:** Incorrect because neonates have immature cell-mediated immunity; exposure without prophylaxis leads to a very high rate of progression to active disease. * **Options C & D:** These represent "Treatment" rather than "Prophylaxis." Full multi-drug therapy is only indicated if the neonate shows clinical signs of **Congenital TB** or has a positive evaluation (e.g., abnormal Chest X-ray or positive gastric aspirate for AFB). **High-Yield Clinical Pearls for NEET-PG:** * **Breastfeeding:** It is **not contraindicated**. The mother should continue breastfeeding while wearing a mask and practicing cough hygiene. * **Congenital TB:** The most common site of the primary complex in congenital TB is the **Liver** (due to umbilical vein spread), whereas in post-natal TB, it is the **Lungs**. * **Separation:** The infant should **not** be separated from the mother unless she is too ill to care for the child or has MDR-TB. * **Pyridoxine:** Should be supplemented (1 mg/kg) along with INH to prevent peripheral neuropathy.

Q: Koplik spots are seen in which of the following conditions?

Measles. **Explanation:** **Koplik spots** are the pathognomonic clinical sign of **Measles (Rubeola)**. They are small, irregular, bluish-white grains on an erythematous base (often described as "grains of salt on a red background") found on the buccal mucosa, typically opposite the lower second molars. They appear during the **prodromal stage**, approximately 48 hours before the characteristic maculopapular rash, and disappear as the rash breaks out. **Analysis of Options:** * **Mumps:** Characterized by painful swelling of the parotid glands (parotitis). It does not feature an enanthem like Koplik spots. * **Influenza:** A respiratory viral infection presenting with high fever, cough, and myalgia; it lacks specific oral mucosal findings. * **Rubella (German Measles):** While it presents with a rash, its characteristic oral finding is **Forchheimer spots** (small, red petechiae on the soft palate), which are not pathognomonic. **NEET-PG High-Yield Pearls:** * **Pathognomonic Sign:** Koplik spots = Measles. * **Timeline:** They appear in the prodromal phase and fade as the rash starts (which spreads in a cephalocaudal direction). * **Vitamin A:** Supplementation is crucial in measles management to reduce morbidity and mortality (especially ocular complications). * **Complications:** The most common complication is Otitis Media; the most common cause of death is Pneumonia; the most dreaded late complication is SSPE (Subacute Sclerosing Panencephalitis).

Q: Pleomorphism is seen in which of the following conditions?

Chickenpox. **Explanation:** **Pleomorphism** in the context of viral exanthems refers to the simultaneous presence of skin lesions in **different stages of development** (macules, papules, vesicles, and crusts) in the same anatomical area. 1. **Why Chickenpox is correct:** Chickenpox, caused by the **Varicella-Zoster Virus (VZV)**, is characterized by a "centripetal" rash that appears in successive crops. Because new lesions appear while older ones are healing, all stages of the rash are visible at once. This is a hallmark clinical feature of VZV. 2. **Why other options are incorrect:** * **Smallpox:** Unlike Chickenpox, the rash in Smallpox is **monomorphic**. All lesions in a particular area are at the same stage of development (e.g., all are pustules). * **Rubella (German Measles):** Presents with a pinkish maculopapular rash that spreads rapidly downwards (cephalocaudal) and disappears in the same order. It does not exhibit pleomorphism. * **Toxocara:** This is a helminthic infection (Visceral Larva Migrans) and does not typically present with a pleomorphic vesicular rash. **High-Yield Clinical Pearls for NEET-PG:** * **Dew-drop on a rose petal:** Classic description of the Varicella vesicle on an erythematous base. * **Centripetal distribution:** Chickenpox rash is more profuse on the trunk than the face and extremities (opposite of Smallpox). * **Scabs:** In Chickenpox, the crusts/scabs are **not infectious** (unlike the vesicular fluid). * **Tzanck Smear:** Used for rapid diagnosis; shows **multinucleated giant cells** with Cowdry Type A intranuclear inclusion bodies.

Question 1

Large bilateral painless effusions of the knees occurring in late congenital syphilis in patients between ages 8 to 18 are designated as?

Accepted Answer

Clutton's joints

Answer

Ramsey's joints

Answer

Charcot's joints

Answer

Mercer's joints

Question 2

Which of the following is true about roseola infantum?

Accepted Answer

Caused by HHV 6 and 7

Answer

Defervescence follows the rash

Answer

Slapped cheek appearance is seen

Answer

Otitis media is a common complication

Question 3

A 2-year-old child has a Mantoux test reading of 12 mm after 48 hours. What is the appropriate management in this case?

Accepted Answer

Anti-TB drugs should be started even if chest X-ray and hemogram are normal.

Answer

Treatment should be started only if chest X-ray and hemogram are suggestive.

Answer

Wait until overt signs of TB appear.

Answer

No treatment is required.

Question 4

What is the treatment of varicella in an immunocompetent host?

Accepted Answer

Prevention of complications

Answer

Acyclovir

Answer

Acyclovir and vaccination

Answer

Immunoglobulin

Question 5

What is the recommended treatment for an infant born to a mother with active tuberculosis?

Accepted Answer

Isoniazid prophylaxis

Answer

No treatment required

Answer

Full treatment with Isoniazid, Rifampicin, and Ethambutol

Answer

Treatment with Isoniazid and Rifampicin

Question 6

A 5-year-old child presents with a febrile illness characterized by cough and a blotchy rash. The child has not received routine pediatric care. On examination, there is lymphadenopathy and an erythematous, maculopapular rash behind the ears and along the hairline, involving the neck and, to a lesser extent, the trunk. Examination of this patient's oropharynx would likely reveal which lesion?

Accepted Answer

Multiple small white spots on the buccal mucosa

Answer

Adherent thin, whitish patch on gingiva

Answer

Cold sores on the lips

Answer

Curdy white material overlying an erythematous base on the oral mucosa

Question 7

Which statement is true regarding the transmission of HIV to an infant from an infected mother?

Accepted Answer

Administer zidovudine during labor.

Answer

There is a 25% chance of vertical transmission.

Answer

Avoid breastfeeding.

Answer

Vaccinate the infant with OPV and MMR.

Question 8

Koplik spots are seen in which of the following conditions?

Accepted Answer

Measles

Answer

Mumps

Answer

Influenza

Answer

Rubella

Question 9

A 6-year-old boy develops symptoms of cough, fever, and malaise followed by a generalized maculopapular rash that has spread from the head downward. A clinical diagnosis of measles is made. A few days after the onset of the rash he is drowsy, lethargic, and complaining of headache. Lumbar puncture, electroencephalogram (EEG), and computerized tomography (CT) of the brain exclude other etiologies and confirm the diagnosis of encephalitis. Which of the following is the most likely delayed neurologic complication of measles virus encephalitis?

Accepted Answer

Mental retardation or epilepsy

Answer

Meningitis

Answer

Pure motor paralysis

Answer

Autonomic neuropathy

Question 10

Pleomorphism is seen in which of the following conditions?

Accepted Answer

Chickenpox

Answer

Toxocara

Answer

Rubella

Answer

Smallpox

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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