Cutaneous Manifestations of Malaria — MCQs
The following pathological features are associated with Plasmodium falciparum except-
A 34-year-old lady presents with high grade fever with chills and rigors. On examination a firm spleen is felt 3 cm below costal margin with right upper quadrant tenderness. Peripheral smear was prepared. Diagnosis is?
Which of the following statements regarding diagnosis of malaria are true?
Which among the following occupations is a risk factor for cutaneous larva migrans?
In a community with one lakh population, 20,000 slides were examined in a particular year. Out of these 100 were positive for malarial parasite. What is the Annual Parasite Incidence (API) in this community ?
In the context of malaria control, when is regular insecticidal spray recommended based on the Annual Parasite Index (API)?
JSB stain is used for which parasite?
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:
Cutaneous Manifestations of Malaria Indian Medical PG Practice Questions and MCQs
Question 1: The following pathological features are associated with Plasmodium falciparum except-
- A. Cytoadherence
- B. Sequestration
- C. Rosetting
- D. Tissue phase (Correct Answer)
Explanation: ***Tissue phase*** (Correct Answer - NOT associated with P. falciparum) - While *Plasmodium falciparum* does have a **hepatic (liver) phase** in its life cycle, the term "**tissue phase**" specifically refers to the **persistent dormant liver stage (hypnozoites)** seen in **relapsing malarias** [1]. - **Hypnozoites** are found in *Plasmodium vivax* and *Plasmodium ovale* but **NOT in *P. falciparum***. - These dormant forms can reactivate months or years later, causing relapse—a feature absent in *P. falciparum* infection. *Cytoadherence* (Incorrect - IS associated with P. falciparum) - This is a **key virulence factor** of *P. falciparum*, where **infected red blood cells (iRBCs)** bind to the **vascular endothelium** via adhesion molecules (PfEMP1) [1]. - This binding leads to **sequestration** in deep capillaries and avoidance of splenic clearance, contributing to severe malaria pathology [1]. *Sequestration* (Incorrect - IS associated with P. falciparum) - Refers to the confinement of **iRBCs** in the **deep microvasculature** of vital organs such as the brain, lungs, and kidneys. - Results from **cytoadherence** and is the primary mechanism behind severe complications like **cerebral malaria** in *P. falciparum*. *Rosetting* (Incorrect - IS associated with P. falciparum) - Involves **iRBCs** binding to uninfected red blood cells, forming **rosette structures**. - This phenomenon impedes blood flow in capillaries and contributes to **microvascular obstruction** and tissue hypoxia in severe *P. falciparum* infections. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Infectious Diseases, pp. 398-400.
Question 2: A 34-year-old lady presents with high grade fever with chills and rigors. On examination a firm spleen is felt 3 cm below costal margin with right upper quadrant tenderness. Peripheral smear was prepared. Diagnosis is?
- A. Plasmodium vivax
- B. Infectious mononucleosis
- C. Plasmodium falciparum (Correct Answer)
- D. Amoebic liver abscess
Explanation: ***Plasmodium falciparum*** - **High-grade fever with chills and rigors** is a classic presentation of malaria, often more severe with *P. falciparum* [1]. - **Splenomegaly** and **right upper quadrant tenderness** can occur in severe malaria due to liver and spleen involvement, especially with *P. falciparum*'s ability to cause profound organ dysfunction [1]. *Plasmodium vivax* - While *P. vivax* causes fever, chills, and rigors, it typically presents with a **tertian fever pattern** (fever every 48 hours), and severe complications like significant right upper quadrant tenderness are less common than with *P. falciparum* [1]. - **Splenomegaly** can be present, but the overall severity and potential for complications are higher in *P. falciparum* [1]. *Infectious mononucleosis* - Characterized by **fever, fatigue, pharyngitis**, and **lymphadenopathy**, often with splenomegaly. - However, **right upper quadrant tenderness** and the acute, severe presentation with prominent chills and rigors described are less typical of infectious mononucleosis. *Amoebic liver abscess* - This typically presents with **fever** and **right upper quadrant pain**, often with a tender hepatomegaly. - However, **prominent chills and rigors** are less common, and it is usually not associated with a palpable, firm spleen as a primary feature.
Question 3: Which of the following statements regarding diagnosis of malaria are true?
- A. Thin blood film is used to determine parasite concentration.
- B. As the sensitivity of microscopy is low, it is useful to detect parasite load at high concentrations only.
- C. Jaswant Singh Bhattacharya (JSB) Stain is used. (Correct Answer)
- D. Thick blood film is used to detect plasmodium species causing infection.
Explanation: ***Correct: Jaswant Singh Bhattacharya (JSB) Stain is used.*** - **JSB stain** is a rapid and effective method for staining malaria parasites in blood films, particularly in resource-limited settings where traditional Romanowsky stains might not be readily available. - Its quick staining time (3-5 minutes) and ease of use make it valuable for prompt diagnosis of malaria. - This is the **most clearly correct** statement as JSB stain is definitively used in malaria diagnosis. *Thick blood film is used to detect plasmodium species causing infection.* - A **thick blood film** is primarily used for **detecting** the presence of malaria parasites due to its higher sensitivity in screening larger volumes of blood (concentrates parasites 20-40 times). - However, it is **not ideal for species identification** due to distorted RBC morphology and lysed red blood cells. - The statement is **misleading** - while thick films detect parasites, they are not the preferred method for determining the **specific species**. *Thin blood film is used to determine parasite concentration.* - This statement is **technically correct** - thin blood films ARE used to determine parasite concentration (parasitemia) and for speciation. - However, in the context of this question, **JSB stain is the better answer** as it is more specifically and uniquely associated with malaria diagnosis, whereas thin films have broader applications. - Thin films allow accurate quantification of parasitemia (parasites/µL or percentage of infected RBCs) and species identification due to preserved RBC morphology. *As the sensitivity of microscopy is low, it is useful to detect parasite load at high concentrations only.* - **Incorrect** - Microscopy, particularly with thick blood films, has **high sensitivity** and is considered the gold standard for malaria diagnosis. - Microscopy can detect parasites at concentrations as low as **50-100 parasites/µL** (approximately 0.001% parasitemia). - While operator-dependent, it is certainly not limited to detecting parasites only at high concentrations.
Question 4: Which among the following occupations is a risk factor for cutaneous larva migrans?
- A. A poultry worker
- B. A kennel worker
- C. A lifeguard in a swimming pool
- D. Farmer (Correct Answer)
Explanation: ***Farmer*** - Farmers are at high risk due to frequent direct contact with **contaminated soil** or sandy environments where animal feces, especially from dogs and cats, might be present. - Exposure to **larvae of hookworms** such as *Ancylostoma braziliense* and *Ancylostoma caninum*, which can penetrate unprotected skin (e.g., bare feet while working) from the soil. *A lifeguard in a swimming pool* - Lifeguards primarily work in **chlorinated water** or on clean, well-maintained pool decks, which do not typically harbor hookworm larvae. - While they might be exposed to other skin conditions, **cutaneous larva migrans** is not a common risk associated with this occupation. *A poultry worker* - Poultry workers are primarily exposed to avian environments, where hookworm species that cause cutaneous larva migrans in humans are typically **not found**. - Their work environment generally does not involve direct contact with soil contaminated by **canine or feline feces**. *A kennel worker* - While kennel workers handle dogs and cats, which are carriers of hookworms, their primary exposure is to the animals themselves or their immediate cleaned environments, not typically **soil contaminated with larvae**. - The mode of transmission for cutaneous larva migrans is through **soil contact** rather than direct animal handling in a controlled kennel setting.
Question 5: In a community with one lakh population, 20,000 slides were examined in a particular year. Out of these 100 were positive for malarial parasite. What is the Annual Parasite Incidence (API) in this community ?
- A. 2
- B. 0.5
- C. 1 (Correct Answer)
- D. 5
Explanation: ***Correct Answer: 1*** The **Annual Parasite Incidence (API)** is a key epidemiological indicator for malaria surveillance, defined as the number of **confirmed positive malaria cases per 1,000 population per year**. **Formula:** API = (Number of positive cases / Total population) × 1,000 **Calculation:** - Population = 1,00,000 (one lakh) - Positive cases = 100 - API = (100 / 1,00,000) × 1,000 = **1** The number of slides examined (20,000) is relevant for calculating the **Slide Positivity Rate (SPR)** but not directly used in the API calculation. *Incorrect: 2* - This would be correct if there were 200 positive cases in the same population - Represents double the actual API *Incorrect: 0.5* - This would be correct if there were only 50 positive cases in the population - Represents half the actual API *Incorrect: 5* - This would result from incorrectly using the number of slides examined (20,000) as the denominator instead of the total population (1,00,000) - Confuses SPR calculation methodology with API calculation
Question 6: In the context of malaria control, when is regular insecticidal spray recommended based on the Annual Parasite Index (API)?
- A. < 1
- B. < 2
- C. > 2 (Correct Answer)
- D. > 1
Explanation: ***> 2*** - Regular insecticidal spray, particularly **Indoor Residual Spraying (IRS)**, is a key malaria control measure recommended when the **Annual Parasite Index (API) is greater than 2**. - An API greater than 2 indicates **high endemicity** with a significant burden of malaria transmission in the community, necessitating aggressive vector control strategies. - According to **NVBDCP (National Vector Borne Disease Control Programme) guidelines**, API > 2 defines high-risk areas where routine IRS is implemented as a core intervention. *> 1* - An API between 1-2 represents **moderate endemicity**, where the focus is primarily on **active case detection, prompt treatment, and targeted interventions** rather than universal spraying. - While vector control remains important, routine widespread IRS is not the standard recommendation at this threshold. *< 2* - An API of less than 2 (which includes both moderate and low endemic areas) does not routinely warrant universal insecticidal spraying programs. - In areas with API < 2, **case management, surveillance, and selective vector control** are prioritized over widespread IRS campaigns. *< 1* - An API of less than 1 indicates **low endemicity**, where malaria transmission is minimal and sporadic. - In such areas, **surveillance, prompt case detection and treatment, and targeted interventions** are the mainstay, with IRS reserved only for focal outbreaks or high-risk pockets.
Question 7: JSB stain is used for which parasite?
- A. Kala azar
- B. Sleeping sickness
- C. Malaria
- D. Filaria (Correct Answer)
Explanation: ***Filaria*** - The **JSB stain (Jaswant Singh Battacharya stain)** is a rapid Romanowsky-type stain specifically developed for the diagnosis of **microfilariae** in blood films. - It allows for clear visualization of the sheaths and nuclei of microfilariae, which is crucial for species identification and diagnosis of **filariasis**. *Malaria* - **Giemsa stain** is the gold standard for identifying malaria parasites in thick and thin blood smears, not JSB stain. - Giemsa allows for detailed morphological differentiation of malaria species and stages within **red blood cells**. *Kala azar* - **Kala-azar (visceral leishmaniasis)** is diagnosed by detecting **Leishman bodies (amastigotes)** in bone marrow, splenic, or lymph node aspirates. - Stains like **Giemsa** or **Leishman stain** are traditionally used for visualizing these amastigotes. *Sleeping sickness* - **Sleeping sickness (African trypanosomiasis)** is diagnosed by identifying **trypomastigotes** in blood smears, lymph node aspirates, or cerebrospinal fluid. - **Giemsa stain** is commonly used for the microscopic examination of these specimens to detect the parasites.
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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