Parasitic Zoonoses — MCQs
Which among the following occupations is a risk factor for cutaneous larva migrans?
A baby presents with recurrent ear infections with discharge, seborrheic dermatitis, hepatosplenomegaly, and cystic skull lesions. What is the most likely diagnosis?
Katayama fever is caused by which of the following?
A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?
Cysticercosis presents as a) Seizure b) Neuropathy c) Encephalitis d) Muscular hypertrophy
A baby presents with hydrocephalus, intracranial calcifications, and chorioretinitis. What is the most probable diagnosis?
A patient presents with severe abdominal pain and jaundice. Imaging reveals calcified cysts in the liver, and serological testing is positive for Echinococcus. What is a potential complication of this infection?
A 5-year-old child presented with fever, fatigue, abdominal pain, and vomiting. On further history evaluation, he had a habit of eating dog feces. Investigations show visceral larva migrans. Which animal is the most likely source of this infection in this child?
Which of the following parasite is shown below?
The following organism is called:
Parasitic Zoonoses Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: A baby presents with recurrent ear infections with discharge, seborrheic dermatitis, hepatosplenomegaly, and cystic skull lesions. What is the most likely diagnosis?
- A. Hemophagocytic lymphohistiocytosis
- B. Multiple myeloma
- C. Langerhans cell histiocytosis (Correct Answer)
- D. Acute lymphoblastic leukemia (ALL)
Explanation: ***Langerhans cell histiocytosis*** - This classic presentation involves a constellation of symptoms including **seborrheic dermatitis-like rash**, recurrent ear infections with discharge (due to infiltration of the mastoid bone), hepatosplenomegaly, and **cystic skull lesions**, all highly suggestive of Langerhans cell histiocytosis (LCH). - LCH is a rare disorder characterized by the proliferation of abnormal Langerhans cells, which can affect various organs and systems. *Hemophagocytic lymphohistiocytosis* - While patients with Hemophagocytic Lymphohistiocytosis (HLH) can present with **hepatosplenomegaly** and recurrent infections, they typically have high fevers, cytopenias, and poor clinical condition. - HLH does not typically cause **seborrheic dermatitis-like rashes** or **cystic bone lesions**. *Multiple myeloma* - Multiple myeloma is a **plasma cell malignancy** that predominantly affects older adults and is characterized by bone pain, anemia, renal failure, and hypercalcemia. - It does not present with recurrent ear infections, seborrheic dermatitis, or hepatosplenomegaly in this manner, and is exceedingly rare in infants. *Acute lymphoblastic leukemia (ALL)* - ALL is the most common childhood cancer and can cause **hepatosplenomegaly**, recurrent infections (due to neutropenia), and sometimes bone pain. - However, **seborrheic dermatitis-like rash** and **cystic skull lesions** are not typical features of ALL.
Question 3: Katayama fever is caused by which of the following?
- A. F. hepatica
- B. C. sinensis
- C. A. lumbricoides
- D. S. japonicum (Correct Answer)
Explanation: ***Correct: S. japonicum*** - Katayama fever, also known as **acute schistosomiasis**, is a systemic hypersensitivity reaction to the migrating schistosomula and oviposition of eggs that primarily occurs in infections with **_Schistosoma japonicum_** or _S. mansoni_. - It presents with fever, chills, cough, diarrhea, abdominal pain, hepatosplenomegaly, and eosinophilia, typically 2-8 weeks after exposure to contaminated water. - S. japonicum tends to cause the most severe form of Katayama fever. *Incorrect: F. hepatica* - **_Fasciola hepatica_** causes fascioliasis, an infection of the bile ducts and liver, which can present with fever and eosinophilia, but it does not typically cause the acute systemic reaction known as Katayama fever. - The disease is usually acquired by ingesting **metacercariae** on aquatic vegetation or in contaminated water. *Incorrect: C. sinensis* - **_Clonorchis sinensis_** is the Chinese liver fluke, causing clonorchiasis, an infection primarily of the bile ducts. - Symptoms are often mild or asymptomatic but can include abdominal pain, indigestion, diarrhea, and jaundice in heavy infections, without the distinct acute systemic syndrome of Katayama fever. *Incorrect: A. lumbricoides* - **_Ascaris lumbricoides_** is a roundworm that causes ascariasis, primarily affecting the gastrointestinal tract. - While it can cause pulmonary symptoms during larval migration (Löffler's syndrome), it does not cause Katayama fever, which is specific to schistosomiasis.
Question 4: A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?
- A. Strongyloides stercoralis (Correct Answer)
- B. Ascaris lumbricoides
- C. Ancylostoma duodenale
- D. Schistosoma mansoni
Explanation: ***Strongyloides stercoralis*** - The presence of **larvae** in the stool [2], particularly **rhabditiform larvae**, is characteristic of *Strongyloides stercoralis* infection, as this parasite has an **autoinfective cycle** involving larval stages in the human host [2]. - In HIV-positive patients, *Strongyloides* can cause **hyperinfection syndrome**, leading to severe gastrointestinal symptoms like foul-smelling stools, and increased larval shedding [2]. *Ascaris lumbricoides* - *Ascaris lumbricoides* is a large intestinal nematode, but it typically presents with **ova** (eggs) in the stool, not larvae, as the eggs hatch in the small intestine. - While it can cause gastrointestinal symptoms, the hallmark microscopic finding in stool samples is the presence of **mammillated or decorticated eggs**. *Ancylostoma duodenale* - *Ancylostoma duodenale* (hookworm) infections are identified by the presence of **eggs** in the stool [1], which are typically oval with a thin shell and contain a developing larva. - Hookworm larvae usually develop in **soil** and infect humans through skin penetration, rather than being commonly found in stool samples from intestinal infection [1]. *Schistosoma mansoni* - *Schistosoma mansoni* is a **blood fluke** that causes intestinal schistosomiasis, characterized by the presence of **spined eggs** in the stool. - The parasite's life cycle involves **freshwater snails** as intermediate hosts, and a **larval stage (cercariae)** that penetrates human skin, but larvae are not typically found in human stool.
Question 5: Cysticercosis presents as a) Seizure b) Neuropathy c) Encephalitis d) Muscular hypertrophy
- A. Muscular hypertrophy
- B. Encephalitis
- C. Neuropathy
- D. Seizure (Correct Answer)
Explanation: ***Seizure*** - **Neurocysticercosis**, caused by *Taenia solium* larvae in the brain, is the **leading cause of acquired epilepsy** worldwide. - The presence of the cysts can irritate brain tissue, leading to **focal or generalized seizures** [1]. *Muscular hypertrophy* - This is a condition of increased muscle mass, often due to exercise or certain medical conditions, and is not a direct presentation of cysticercosis. - While cysticercosis can affect muscles (myocysticercosis), it typically causes **pain, swelling, or pseudohypertrophy** rather than true hypertrophy. *Encephalitis* - **Encephalitis** is inflammation of the brain parenchyma, which can be caused by infections, but neurocysticercosis more commonly presents with symptoms related to **mass effect, hydrocephalus, or seizures** rather than diffuse inflammation. - While **cysticercal encephalitis** is a rare, severe form, especially in children, it's not the most common presentation. *Neuropathy* - **Neuropathy** refers to damage or dysfunction of one or more nerves, typically leading to weakness, numbness, or pain. - Cysticercosis generally affects the **central nervous system** (brain and spinal cord) rather than peripheral nerves, making neuropathy an uncommon presentation [2].
Question 6: A baby presents with hydrocephalus, intracranial calcifications, and chorioretinitis. What is the most probable diagnosis?
- A. Toxoplasmosis (Correct Answer)
- B. Syphilis
- C. Cytomegalovirus (CMV) infection
- D. Rubella
- E. Herpes Simplex Virus (HSV) infection
Explanation: **Toxoplasmosis** - The classic triad of **hydrocephalus**, **intracranial calcifications**, and **chorioretinitis** is highly characteristic of congenital toxoplasmosis. - These findings result from the parasite's invasive nature and predilection for the central nervous system and eyes of the developing fetus. - Calcifications in toxoplasmosis are typically **diffuse and scattered** throughout the brain parenchyma. *Syphilis* - Congenital syphilis typically presents with **rhinitis**, **skin rash**, **hepatosplenomegaly**, and **bone abnormalities** (e.g., periostitis, saber shins). - While neurological complications can occur, the specific triad of hydrocephalus, intracranial calcifications, and chorioretinitis is not characteristic. *Cytomegalovirus (CMV) infection* - Congenital CMV can cause **periventricular calcifications** (not diffuse calcifications), **microcephaly**, and **sensorineural hearing loss**. - While chorioretinitis can occur, hydrocephalus is less frequent, and the calcification pattern differs from toxoplasmosis (CMV shows periventricular pattern vs. diffuse in toxoplasmosis). *Rubella* - Congenital rubella syndrome is known for causing the classic triad of **cataracts**, **sensorineural hearing loss**, and **congenital heart defects** (e.g., patent ductus arteriosus, pulmonary artery stenosis). - Intracranial calcifications and hydrocephalus are not typical presentations of congenital rubella. *Herpes Simplex Virus (HSV) infection* - Neonatal HSV typically presents with **vesicular skin lesions**, **encephalitis**, and **disseminated disease** affecting liver and lungs. - While HSV can cause encephalitis with brain involvement, the classic triad of hydrocephalus, diffuse intracranial calcifications, and chorioretinitis is not characteristic of HSV infection.
Question 7: A patient presents with severe abdominal pain and jaundice. Imaging reveals calcified cysts in the liver, and serological testing is positive for Echinococcus. What is a potential complication of this infection?
- A. Portal hypertension due to cyst compression
- B. Rupture of cysts leading to anaphylactic shock
- C. No significant complications
- D. Secondary bacterial infection of cysts (Correct Answer)
Explanation: ***Secondary bacterial infection of cysts*** - **Hydatid cysts** can become secondarily infected, typically after rupture or surgical manipulation, leading to an **abscess formation** within the liver. - This complication can present with features like fever, worsening abdominal pain, and an elevated **white blood cell count**, distinct from the initial presentation. *Rupture of cysts leading to anaphylactic shock* - While rupture of **hydatid cysts** can lead to **anaphylactic shock** due to the release of hydatid fluid, it is not the *most common immediate complication* or the scenario implied by abdominal pain and jaundice. - **Anaphylaxis** implies a rapid, severe systemic allergic reaction, which is a life-threatening acute event. *Portal hypertension due to cyst compression* - While large cysts can compress structures, significant **portal hypertension** due to direct compression of the portal vein by **hydatid cysts** is rare. - More commonly, portal hypertension is a complication of advanced **cirrhosis**, not typically direct cyst compression in the early stages described. *No significant complications* - **Echinococcosis** (hydatid disease) is a serious parasitic infection that almost always leads to significant morbidity if left untreated. - Cysts grow over time and inevitably cause **organ dysfunction**, pain, obstruction, or other complications.
Question 8: A 5-year-old child presented with fever, fatigue, abdominal pain, and vomiting. On further history evaluation, he had a habit of eating dog feces. Investigations show visceral larva migrans. Which animal is the most likely source of this infection in this child?
- A. Pig
- B. Monkeys
- C. Cows
- D. Dogs (Correct Answer)
Explanation: ***Dogs*** - The history of eating **dog feces** directly links to the transmission of **Toxocara canis** eggs, the primary cause of visceral larva migrans. - Humans, especially children, can get infected by ingesting infective eggs from contaminated soil or dog feces. *Pig* - While pigs can harbor parasites like **Taenia solium** (pork tapeworm) and **Trichinella spiralis**, these do not typically cause visceral larva migrans. - Transmission from pigs usually involves consumption of undercooked pork, not direct contact with feces in the context of visceral larva migrans. *Monkeys* - Monkeys are not a common source of parasites causing human visceral larva migrans. - Parasitic infections associated with monkeys in humans are generally rare and usually specific to certain geographical contexts or exotic pet exposure. *Cows* - Cows can be hosts for parasites such as **Taenia saginata** (beef tapeworm), but they are not associated with visceral larva migrans caused by *Toxocara* species. - Ingestion of raw or undercooked beef is the typical mode of transmission for cow-related parasitic infections.
Question 9: Which of the following parasite is shown below?
- A. Cysticercosis cellulosae
- B. Echinococcus granulosus (Correct Answer)
- C. E. Histolytica
- D. Fasciola hepatica
Explanation: ***Echinococcus granulosus*** - The image displays a **hydatid cyst**, characterized by its thick, laminated outer wall (ectocyst) and an inner germinal layer (endocyst) from which **brood capsules** and **protoscolices** (seen as invaginations) bud off. - This morphology is pathognomonic for **Echinococcus granulosus**, the causative agent of **cystic echinococcosis** (hydatid disease). *Cysticercosis cellulosae* - Cysts of *Cysticercus cellulosae* (larval stage of *Taenia solium*) typically appear as a fluid-filled bladder with a single **invaginated scolex** lacking the complex brood capsule arrangement seen in the image. - They also generally have a thinner cyst wall compared to *Echinococcus* cysts. *E. Histolytica* - *Entamoeba histolytica* is a **protozoan parasite** that causes amoebiasis, presenting as trophozoites or cysts; it does not form macroscopic cysts with complex internal structures like the one shown. - Amoebic abscesses are typically necrotic lesions, not true cysts with parasitic structures within. *Fasciola hepatica* - *Fasciola hepatica* is a **trematode (fluke)**, and its larval stages or adult worms do not form cysts with this characteristic morphology. - Liver flukes would appear as tissue sections of the flatworm itself in infected organs, not as a large, spherical cyst with internal budding structures.
Question 10: The following organism is called:
- A. Cestode (Correct Answer)
- B. Nematode
- C. Trematode
- D. Annelid
Explanation: ***Cestode*** - The image displays a long, **segmented, ribbon-like worm**, which is characteristic morphology of a **tapeworm (cestode)**. - Cestodes typically possess a head (scolex) for attachment and a body composed of repeating segments called **proglottids**. *Nematode* - **Nematodes** are generally **unsegmented**, cylindrical, and elongated worms, often described as roundworms. - They lack the distinct proglottids and flattened, ribbon-like appearance seen in the image. *Trematode* - **Trematodes**, also known as flukes, are typically **leaf-shaped** and **unsegmented**. - They are much broader and flatter than the organism shown, and do not have the visible segmentation. *Annelid* - **Annelids** are segmented worms like earthworms and leeches, but they have a **cylindrical body** with visible external ring-like segments. - Unlike cestodes, annelids have a complete digestive system and lack the flat, ribbon-like morphology and internal proglottid structure characteristic of tapeworms.
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