Tungiasis — MCQs
A patient presents with a bullseye rash after a tick bite. Which organism is most likely responsible for this condition?
Which of the following diseases is primarily transmitted by body lice?
A long-term diabetic patient with blisters walked barefoot for a few miles on hot sand. He presented with rapidly spreading deep tissue infection with extensive tissue necrosis. What is the most probable diagnosis?
A person reports 4 hours after having a clean wound without laceration. He had taken TT 10 years before. The next step in management is:
A 30-year-old man reports 4 hours after acquiring a clean wound without laceration. He had received TT vaccination 10 years back. What do you advise regarding tetanus prophylaxis?
All of the following statements about 'yaws' are true, except:
Which of the following is not a feature of dermatomyositis?
Adult scabies is characterized by which of the following?
An 8-month-old child presented with itchy, exudative lesions on the face, palms, and soles. The siblings also have similar complaints. Which of the following is the treatment of choice?
Cutaneous larva migrans is caused by:
Tungiasis Indian Medical PG Practice Questions and MCQs
Question 1: A patient presents with a bullseye rash after a tick bite. Which organism is most likely responsible for this condition?
- A. Borrelia burgdorferi (Correct Answer)
- B. Rickettsia rickettsii
- C. Treponema pallidum
- D. Leptospira interrogans
Explanation: ***Correct: Borrelia burgdorferi*** - **Lyme disease**, caused by *Borrelia burgdorferi*, is classically characterized by an **erythema migrans** rash, which is often described as a **"bullseye"** or target-like lesion, developing after a tick bite. - This **spirochete** is transmitted to humans through the bite of infected *Ixodes* ticks and is the most common cause of vector-borne disease in the United States. *Incorrect: Rickettsia rickettsii* - This organism causes **Rocky Mountain spotted fever**, which typically presents with a **maculopapular rash** that begins on the ankles and wrists and spreads centrally. - While also transmitted by ticks, it does not typically cause a bullseye-shaped erythema migrans rash. *Incorrect: Treponema pallidum* - This bacterium is the causative agent of **syphilis** and is transmitted through sexual contact, not tick bites. - The primary lesion of syphilis is a **chancre**, a painless ulcer, which is distinct from a bullseye rash. *Incorrect: Leptospira interrogans* - This spirochete is responsible for **leptospirosis**, contracted through contact with contaminated water or animal urine. - It can cause severe systemic symptoms, including fever, headache, muscle pain, and jaundice, but it does not produce a bullseye rash.
Question 2: Which of the following diseases is primarily transmitted by body lice?
- A. Plague
- B. Endemic typhus
- C. Chiggerosis
- D. Trench fever (Correct Answer)
Explanation: ***Trench fever*** - **Trench fever** is caused by the bacterium *Bartonella quintana* and is classically transmitted by the **body louse** acquiring the bacteria from an infected human. - The disease is characterized by relapsing fevers, bone pain (especially in the shins), headache, and rash, and it gained prominence during World War I due to poor hygiene and louse infestations among soldiers. *Plague* - **Plague**, caused by *Yersinia pestis*, is primarily transmitted by the bite of infected **fleas**, usually from rodents to humans. - While human-to-human transmission can occur in pneumonic plague, lice are not the primary vector for bubonic or septicemic forms. *Endemic typhus* - **Endemic (murine) typhus** is caused by *Rickettsia typhi* and is transmitted by the **rat flea** (*Xenopsylla cheopis*), not body lice. - It occurs primarily in areas with rodents and their fleas, typically presenting with fever, headache, and a rash. *Chiggerosis* - **Chiggerosis** (also known as trombiculiasis or scrub itch) is caused by the bite of **chigger mites** (larval mites of the family Trombiculidae), which burrow into the skin. - These mites are not body lice and do not transmit bacterial infections like trench fever; their bites cause intensely itchy papules.
Question 3: A long-term diabetic patient with blisters walked barefoot for a few miles on hot sand. He presented with rapidly spreading deep tissue infection with extensive tissue necrosis. What is the most probable diagnosis?
- A. Burn
- B. Cellulitis
- C. Diabetic foot
- D. Necrotizing fasciitis (Correct Answer)
Explanation: ***Necrotizing fasciitis*** - The rapid spread of deep tissue infection with extensive necrosis, especially in an immunocompromised patient like a diabetic, is highly characteristic of **necrotizing fasciitis**. [1] - **Diabetic peripheral neuropathy** can lead to unnoticed injury (walking barefoot on hot sand) and impaired wound healing, further predisposing to severe infections. [2] *Burn* - While walking on hot sand can cause burns, this patient's presentation of "rapidly spreading deep tissue infection" and "extensive tissue necrosis" goes beyond a typical burn injury, suggesting an overwhelming infection. - Burns primarily involve direct tissue damage from heat, whereas the described pathology is indicative of a **bacterial infection** escalating rapidly. *Cellulitis* - **Cellulitis** is a superficial skin infection that typically presents as localized redness, warmth, and swelling, but it usually does not involve deep tissue necrosis or such rapid, extensive spread. - It lacks the hallmark sign of rapid progression to **necrosis** and involvement of deep fascial planes that necessitate urgent surgical debridement. *Diabetic foot* - **Diabetic foot** is a broad term encompassing various foot complications in diabetes, including ulcers, infections, and Charcot arthropathy. While this patient has a diabetic foot, the specific presentation of **rapidly spreading infection** with **extensive necrosis** points to a particular, severe diagnosis within the diabetic foot spectrum, rather than the general term. [2] - The context describes a specific acute, life-threatening infectious process rather than the chronic complications typically associated with the general term "diabetic foot."
Question 4: A person reports 4 hours after having a clean wound without laceration. He had taken TT 10 years before. The next step in management is:
- A. No need for any vaccine (Correct Answer)
- B. Full course Tetanus vaccine to be given
- C. Full dose TT with TIG
- D. Single-dose TT
Explanation: ***No need for any vaccine*** - For a **clean, minor wound** (non-tetanus-prone), if the patient has completed primary immunization and the last TT dose was given **≤10 years ago**, no booster is required. - The patient received TT **10 years before**, which falls within the protective window for **clean wounds**. - Tetanus prophylaxis guidelines distinguish between clean wounds and tetanus-prone wounds; clean wounds have more lenient requirements. - **Key principle**: The 10-year booster rule applies when last dose was **>10 years ago** (i.e., 11+ years), not at exactly 10 years for clean wounds. *Single-dose TT* - A **TT booster** would be indicated if: - The wound was **tetanus-prone** (dirty, contaminated, deep puncture, devitalized tissue) AND last dose was 5-10 years ago, OR - This was a **clean wound** but last TT was **>10 years ago** (more than 10 years) - Since this is a clean wound at exactly 10 years, immediate vaccination is not necessary. *Full course Tetanus vaccine to be given* - A **full primary series** is only indicated for: - Patients who have **never been vaccinated**, or - Those with **unknown or incomplete** vaccination history (<3 doses) - This patient has documented prior TT immunization, so a full course is inappropriate. *Full dose TT with TIG* - **Tetanus Immunoglobulin (TIG)** is reserved for high-risk situations: - **Tetanus-prone wounds** in patients with <3 doses or unknown vaccination status, or - **Tetanus-prone wounds** with last dose **>10 years ago** - This patient has a **clean, non-tetanus-prone wound** with adequate vaccination history, making TIG unnecessary and an over-treatment.
Question 5: A 30-year-old man reports 4 hours after acquiring a clean wound without laceration. He had received TT vaccination 10 years back. What do you advise regarding tetanus prophylaxis?
- A. No vaccination needed
- B. 1 dose of TT AND TIG
- C. full course of TT
- D. single dose of TT (Correct Answer)
Explanation: ***single dose of TT*** - For a **clean wound** in a patient who received a **TT vaccination 10 years ago**, a single dose of **Tetanus Toxoid (TT)** is sufficient to boost immunity. - This patient's previous vaccination history provides a baseline immunity, and a booster ensures continued protection against tetanus. *No vaccination needed* - Even with a "clean" wound, if the last vaccination was 10 years ago, the patient's **antibody levels** might be insufficient for full protection against tetanus. - Tetanus is a serious, often fatal, disease, making prophylaxis crucial even for minor wounds. *1 dose of TT AND TIG* - **Tetanus immunoglobulin (TIG)** is reserved for **dirty or contaminated wounds** or for individuals with an **unknown or incomplete vaccination history**. - In this case, the wound is clean and the patient has prior vaccination, so TIG is not indicated. *full course of TT* - A **full course of TT** (multiple doses) is typically recommended for individuals with an **unknown or incomplete vaccination history** to establish primary immunity. - Since this patient had a vaccination 10 years ago, they already possess foundational immunity, and only a booster is required.
Question 6: All of the following statements about 'yaws' are true, except:
- A. Caused by Treponema pertenue
- B. Late stages of yaws involve heart and nerves (Correct Answer)
- C. Transmitted non-venereally
- D. Secondary yaws can involve bone
Explanation: ***Late stages of yaws involve heart and nerves*** - Unlike **syphilis**, which is caused by *Treponema pallidum subspecies pallidum*, late-stage yaws (caused by *Treponema pallidum subspecies pertenue*) primarily affects the **skin**, **bones**, and **cartilage**, leading to disfigurement, but generally spares the cardiovascular and nervous systems. - The absence of significant **cardiovascular** or **neurological involvement** is a key differentiating factor between yaws and tertiary syphilis. *Caused by Treponema pertenue* - This statement is true; **yaws** is indeed caused by the bacterium *Treponema pertenue*. - *Treponema pertenue* is a spiral-shaped bacterium closely related to the organism that causes syphilis, belonging to the **spirochete** family. *Transmitted non-venereally* - This statement is true; yaws is typically transmitted through **direct skin-to-skin contact** with an infected person's lesions, often among children in tropical and subtropical regions [1]. - Unlike syphilis, which is primarily a sexually transmitted infection, yaws is **non-venereal**, spreading through casual contact [1]. *Secondary yaws can involve bone* - This statement is true; **secondary yaws** can manifest with various lesions, including **periostitis** and **osteomyelitis**, affecting long bones and other skeletal structures [1]. - Bone involvement manifests as **painful bone swellings** and can lead to **saber shin deformity** or other bone deformities in later stages [1].
Question 7: Which of the following is not a feature of dermatomyositis?
- A. Salmon Patch (Correct Answer)
- B. Periungual telangiectasias
- C. Gottron's patch
- D. Mechanic's hands
Explanation: ***Salmon Patch*** - A **salmon patch** (also known as a nevus simplex or stork bite) is a common, benign vascular birthmark that presents as a flat, red or pink patch. - It is **not associated with dermatomyositis** and has no pathogenic link to the condition. *Gottron's patch* - **Gottron's patches** are a classic cutaneous manifestation of dermatomyositis, characterized by erythematous, violaceous, or dusky red papules or plaques over the **extensor surfaces of the metacarpophalangeal and interphalangeal joints**. - Their presence is highly suggestive of dermatomyositis, often preceding or co-occurring with muscle weakness. *Periungual telangiectasias* - **Periungual telangiectasias** are dilated capillaries around the nail folds and are a common skin manifestation of dermatomyositis. - They represent small vessel vasculopathy, a histological feature, and suggest microvascular damage often seen in systemic connective tissue diseases like dermatomyositis. *Mechanic's hands* - **Mechanic's hands** are a cutaneous feature seen in dermatomyositis (and other inflammatory myopathies like antisynthetase syndrome). - They are characterized by **hyperkeratosis**, fissuring, and scaling of the skin, particularly on the lateral and palmar aspects of the fingers, resembling the hands of a manual laborer.
Question 8: Adult scabies is characterized by which of the following?
- A. Involvement of palms and soles (Correct Answer)
- B. Involvement of the face
- C. Involvement of the anterior abdomen
- D. All of the above
Explanation: **Explanation:** Scabies is a contagious skin infestation caused by the mite *Sarcoptes scabiei var. hominis*. The distribution of lesions is the most critical diagnostic feature in NEET-PG questions. **1. Why Option A is Correct:** In **adult scabies**, the "Circle of Hebra" defines the classic distribution. This includes the interdigital spaces, wrists, elbows, axillae, periumbilical area, and genitalia. While traditionally taught that palms and soles are spared in adults compared to infants, modern clinical dermatology (and standard textbooks like IADVL) recognizes that **palms and soles** are frequently involved in adults, especially in cases of high mite burden or crusted scabies. Among the given options, it is the most characteristic site of involvement. **2. Why Options B and C are Incorrect:** * **Option B (Face):** The face and scalp are characteristically **spared** in adult scabies. This is because adults have a higher density of sebaceous glands; the sebum is thought to be inhibitory to the mites. Facial involvement is a hallmark of **infantile scabies** or **crusted (Norwegian) scabies**. * **Option C (Anterior Abdomen):** While the periumbilical area is involved, "anterior abdomen" is too broad and less specific than the involvement of the palms/soles or the web spaces. **Clinical Pearls for NEET-PG:** * **Infantile Scabies:** Unlike adults, infants show involvement of the **face, scalp, palms, and soles** with common secondary vesicopustules. * **Pathognomonic Sign:** The **Burrow** (a S-shaped track) is the clinical hallmark, most commonly found on the finger webs and wrists. * **Nocturnal Pruritus:** Itching is worst at night due to a Type IV hypersensitivity reaction to the mite, its eggs, and scybala (feces). * **Treatment of Choice:** Topical **Permethrin (5%)** is the gold standard. Oral Ivermectin (200 µg/kg) is an alternative or adjunct for crusted scabies.
Question 9: An 8-month-old child presented with itchy, exudative lesions on the face, palms, and soles. The siblings also have similar complaints. Which of the following is the treatment of choice?
- A. Systemic ampicillin
- B. Topical permethrin (Correct Answer)
- C. Systemic prednisolone
- D. Topical betamethasone
Explanation: ### Explanation **Diagnosis: Infantile Scabies** The clinical presentation of itchy, exudative lesions involving the **palms and soles**, combined with a **positive family history** (siblings affected), is pathognomonic for Scabies. In infants, unlike adults, the lesions frequently involve the face, scalp, palms, and soles and often present as vesicles or pustules due to secondary eczematization. **1. Why Topical Permethrin is Correct:** * **Permethrin (5% cream)** is the **drug of choice** for scabies in infants older than 2 months. * **Mechanism:** It acts by disrupting the sodium channel currents in the neurons of the *Sarcoptes scabiei* mite, leading to paralysis and death. * **Application:** It should be applied from head to toe in infants (including the face and scalp, avoiding eyes/mouth) and washed off after 8–12 hours. **2. Why Other Options are Incorrect:** * **Systemic Ampicillin:** While lesions may appear "exudative" due to secondary bacterial infection (impetiginization), the primary pathology is parasitic. Antibiotics alone will not cure the underlying infestation. * **Systemic Prednisolone & Topical Betamethasone:** These are corticosteroids. Using steroids in scabies is contraindicated as they mask the symptoms ("Scabies Incognito") and can worsen the infestation by suppressing the local immune response against the mites. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice in Pregnancy/Lactation:** Permethrin 5%. * **Ivermectin:** Oral ivermectin (200 µg/kg) is an alternative but is generally **avoided in children weighing <15 kg** or pregnant women. * **Nodular Scabies:** Characterized by reddish-brown itchy nodules in the axilla and genitalia; treated with intralesional steroids. * **Crusted (Norwegian) Scabies:** Seen in immunocompromised patients; characterized by thousands of mites and minimal itching. Requires combination therapy (Oral Ivermectin + Topical Permethrin). * **Key Management Rule:** Always treat all close contacts simultaneously, even if asymptomatic, to prevent re-infestation.
Question 10: Cutaneous larva migrans is caused by:
- A. A. braziliense (Correct Answer)
- B. Toxocara canis
- C. Strongyloides
- D. Necator americanus
Explanation: **Explanation:** **Cutaneous Larva Migrans (CLM)**, also known as "creeping eruption," is a zoonotic infestation caused by the larvae of animal hookworms. 1. **Why A is correct:** The most common causative agent is **Ancylostoma braziliense** (the hookworm of cats and dogs). Humans are accidental "dead-end" hosts. When larvae from soil contaminated with animal feces penetrate human skin, they lack the enzymes necessary to penetrate the basement membrane and enter the circulation. Consequently, they remain confined to the epidermis, migrating aimlessly and creating the characteristic **serpiginous, erythematous, pruritic tracks**. 2. **Why the other options are incorrect:** * **Toxocara canis:** Causes **Visceral Larva Migrans (VLM)** or Ocular Larva Migrans. The larvae migrate through internal organs rather than the skin. * **Strongyloides stercoralis:** Causes **Larva Currens**. This is distinguished by its extreme speed of migration (up to 5–10 cm/hour) and typically starts near the perianal region. * **Necator americanus:** This is a human hookworm. Unlike animal hookworms, it can penetrate the dermis and enter the bloodstream to complete its life cycle, causing systemic hookworm disease rather than localized CLM. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Feet (due to walking barefoot on beaches or moist soil). * **Rate of migration:** 1–2 cm per day (much slower than Larva Currens). * **Löffler’s Syndrome:** Can rarely occur if larvae reach the lungs (transient pulmonary infiltrates with eosinophilia). * **Treatment of choice:** **Albendazole** (400 mg for 3–5 days) or a single dose of **Ivermectin** (200 μg/kg). Topical Thiabendazole is also an option.
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