Parasitology Practice Questions

Q: Katayama fever is caused by which of the following?

S. japonicum. ***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.

Q: Which of the following statements is true regarding Diphyllobothrium?

The operculated egg is a diagnostic feature. ***The operculated egg is a diagnostic feature*** - *Diphyllobothrium latum*, also known as the **fish tapeworm**, produces characteristic **operculated eggs** that are oval-shaped with an operculum (cap) at one end and a small knob at the other. - The presence of these **unembryonated eggs** in stool samples is the primary diagnostic method for diphyllobothriasis. *Humans are the only definitive host* - While humans are common definitive hosts, other **fish-eating mammals** such as bears, dogs, and cats can also serve as definitive hosts for *Diphyllobothrium latum*. - The definitive host is where the **adult worm resides** and reproduces sexually. *Vitamin B12 deficiency always occurs in infection* - **Vitamin B12 deficiency (megaloblastic anemia)** is a known complication of *Diphyllobothrium latum* infection, as the worm competes for B12 in the host's intestine. - However, it does **not occur in all infected individuals**; it is estimated to affect a significant minority, typically those with heavy worm burdens or prolonged infection, and can be influenced by dietary intake. *Fish are definitive hosts* - Fish (specifically freshwater fish like pike, perch, and salmon) act as **second intermediate hosts** for *Diphyllobothrium latum*, carrying the **plerocercoid larvae**. - **Humans and other fish-eating mammals** are the definitive hosts, where the plerocercoid larvae mature into adult tapeworms in the small intestine.

Q: The Hanging Drop method is primarily used for studying which of the following microorganisms?

Trichomonas vaginalis. ***Trichomonas vaginalis*** - The **hanging drop method** is excellent for observing the **motility** of this parasite, which is crucial for its identification due to its characteristic jerky, tumbling movement. - This method helps differentiate it from other non-motile organisms in vaginal fluid samples. *Plasmodium falciparum* - This parasite is primarily identified through examination of **blood smears** (thick and thin films) for its characteristic **intraerythrocytic stages** (rings, trophozoites, schizonts, gametocytes). - It is an **intracellular parasite** and does not exhibit free motility in a hanging drop preparation. *Toxoplasma gondii* - Diagnosis typically involves **serological tests** for antibodies or **PCR** for detecting parasitic DNA, as well as histological examination of tissue biopsies. - While it can move, it's an **obligate intracellular parasite** and is not primarily identified by its motility in a simple hanging drop preparation from clinical samples. *Cryptosporidium parvum* - This parasite is diagnosed by detecting its **oocysts in stool samples** using specialized staining techniques like **acid-fast stain** or immunofluorescence assays. - The oocysts are non-motile and are not identified using the hanging drop method.

Q: Which organism can be isolated from stool & sputum?

Paragonimus. ***Paragonimus*** - *Paragonimus* species, particularly *P. westermani* (the **lung fluke**), are known to infest the lungs, leading to symptoms like **cough** and **sputum production**, where their eggs can be found. - While residing in the lungs, eggs can be swallowed, passed through the gastrointestinal tract, and subsequently found in **stool samples**. *Fasciola* - *Fasciola hepatica* (the **sheep liver fluke**) primarily infects the **liver and biliary ducts**. - Its eggs are typically found in **stool samples** but not in sputum, as it does not infest the respiratory tract. *Clonorchis* - *Clonorchis sinensis* (the **Chinese liver fluke**) also primarily inhabits the **bile ducts** of the liver. - Similar to *Fasciola*, its eggs are excreted in **feces** and are not found in sputum. *P. carinii* - *Pneumocystis jirovecii* (formerly *Pneumocystis carinii*) is a **fungus** that causes **pneumonia** (PCP) in immunocompromised individuals. - It is exclusively found in the **lungs** and identified in respiratory specimens like sputum or bronchoalveolar lavage, not in stool.

Q: Largest intestinal protozoan is?

Balantidium coli. ***Balantidium coli*** - *Balantidium coli* is the **largest protozoan parasite** known to infect humans, specifically found in the intestines. - It causes **balantidiasis**, an intestinal infection, and is notable for its ciliated trophozoite stage. *E. coli* - *E. coli* is a **bacterium**, not a protozoan. - While it is a common inhabitant of the intestines, it is significantly smaller than parasitic protozoa. *Giardia* - *Giardia lamblia* (or *intestinalis*) is a **flagellate protozoan** that causes giardiasis. - Though an intestinal parasite, it is considerably smaller than *Balantidium coli*. *T. gondii* - *Toxoplasma gondii* is an **intracellular protozoan parasite** known for causing toxoplasmosis. - It is much smaller than *Balantidium coli* and primarily infects cells, not existing as a large free-living form in the intestine.

Q: Which type of malaria is most commonly associated with renal failure?

Falciparum. ***Falciparum*** - **Plasmodium falciparum** is notorious for its ability to cause severe and complicated malaria, including **renal failure** due to its high parasitic biomass and tendency to block microvasculature [1]. - The parasite causes red blood cells to become **sticky**, leading to sequestration in capillaries of vital organs, including the kidneys, resulting in acute tubular necrosis [1]. *Vivax* - **Plasmodium vivax** typically causes milder forms of malaria, though it can occasionally lead to severe manifestations, **renal complications are rare** compared to P. falciparum [1]. - While it can cause some organ dysfunction, it generally does not cause the severe multi-organ involvement, particularly **acute renal failure**, that P. falciparum is known for [1]. *Malariae* - **Plasmodium malariae** is associated with a chronic form of malaria and is known to cause **nephrotic syndrome** (specifically malarial nephropathy) due to immune complex deposition, rather than acute renal failure [1]. - The renal pathology in P. malariae infection is typically a **glomerulonephritis** that develops after repeated infections, which is distinct from the acute renal failure seen with P. falciparum [1]. *Ovale* - **Plasmodium ovale** is the least common type of malaria and causes a benign form of the disease, similar to P. vivax [1]. - It rarely, if ever, causes severe complications like **renal failure** [1].

Q: What is the most common protozoan associated with keratitis?

Acanthamoeba. ***Acanthamoeba*** - **Acanthamoeba keratitis** is a serious and painful infection of the eye's cornea, most commonly associated with **contact lens wearers** who do not properly disinfect their lenses. - The organism is a **free-living protozoan** found in soil and water. *Plasmodium* - **Plasmodium** species are the causative agents of **malaria**, a disease that primarily affects **red blood cells** and the liver. - While it can manifest with ocular symptoms like **retinopathy**, it does not typically cause **keratitis**. *Toxoplasma* - **Toxoplasma gondii** causes **toxoplasmosis**, an infection that can lead to **chorioretinitis** (inflammation of the retina and choroid), especially in immunocompromised individuals or congenitally infected infants. - It does not directly cause **keratitis** as its primary ocular manifestation. *Entamoeba histolytica* - **Entamoeba histolytica** is the protozoan responsible for **amebiasis**, particularly **amoebic dysentery** and **liver abscesses**. - Ocular involvement with *Entamoeba histolytica* is extremely rare and typically involves **metastatic lesions** to the orbit or eyelids, not directly primary keratitis.

Q: Flame cells are primarily associated with which of the following organisms?

Trematodes. ***Correct: Trematodes*** - **Flame cells** are specialized **excretory/osmoregulatory structures** found in **Platyhelminthes (flatworms)**, which include **Trematodes** (flukes) and Cestodes (tapeworms). - These cells have a **tuft of cilia** that beat in a flickering motion (resembling a flame), driving fluid through tubules for waste removal and osmoregulation. - **Trematodes** are the most appropriate answer among the given options as they are medically important flatworms with flame cells. *Incorrect: Protozoa* - Protozoa are **single-celled organisms** that use **contractile vacuoles** for osmoregulation, not flame cells. - Examples include Entamoeba, Giardia, and Plasmodium species. *Incorrect: Nematodes* - **Nematodes** (roundworms) belong to phylum Nematoda and possess a distinct excretory system with **renette cells** or **H-shaped/tubular excretory canals**, not flame cells. - Examples include Ascaris, Enterobius, and hookworms. *Incorrect: None of the options* - This is incorrect because **Trematodes** do possess flame cells and is the correct answer among the choices provided.

Q: Cercariae are the infective form of which of the following parasites?

Schistosoma hematobium. ***Schistosoma hematobium*** - **Cercariae** are the motile, free-swimming larval stage of **Schistosoma** species, including *S. hematobium* - They **actively penetrate human skin** to initiate infection, making cercariae the infective form for humans *Paragonimus westermani* - The infective form for humans is **metacercariae**, which are ingested by consuming insufficiently cooked **crabs or crayfish** - Cercariae develop into metacercariae in secondary intermediate hosts (crustaceans) *Fasciola hepatica* - Humans are infected by ingesting **metacercariae** present on aquatic vegetation, such as **watercress** - Cercariae encyst on plants to form metacercariae, not directly infective *Taenia solium* - The infective forms are **cysticerci** in undercooked pork (for adult tapeworm) or **embryonated eggs** (causing cysticercosis) - This cestode has a different life cycle and does **not** involve cercariae

Q: Unsegmented eggs are in which parasite?

Trichuris trichiura. ***Trichuris trichiura*** - *Trichuris trichiura* (whipworm) eggs are typically **unembryonated** or **unsegmented** when passed in feces. - Upon defecation, the eggs require a period of **development in soil** to become infective. *Ancylostoma* - **Hookworm (Ancylostoma)** eggs are typically **segmented** (possessing a 2-8 cell stage) when passed in feces. - They develop into **rhabditiform larvae** in the soil. *Necator americanus* - **Hookworm (Necator americanus)** eggs are also typically **segmented** (possessing a 2-8 cell stage) when passed in feces. - Like *Ancylostoma*, they require further development in soil to become infective. *Dracunculus* - *Dracunculus medinensis* (Guinea worm) does not lay eggs; instead, it releases **larvae** from the skin blister of the host into water. - The larvae are then ingested by **cyclops** (copepods) to continue their life cycle.

Question 1

Katayama fever is caused by which of the following?

Accepted Answer

S. japonicum

Answer

F. hepatica

Answer

C. sinensis

Answer

A. lumbricoides

Question 2

Which of the following statements is true regarding Diphyllobothrium?

Accepted Answer

The operculated egg is a diagnostic feature

Answer

Humans are the only definitive host

Answer

Vitamin B12 deficiency always occurs in infection

Answer

Fish are definitive hosts

Question 3

The Hanging Drop method is primarily used for studying which of the following microorganisms?

Accepted Answer

Trichomonas vaginalis

Answer

Plasmodium falciparum

Answer

Toxoplasma gondii

Answer

Cryptosporidium parvum

Question 4

Which organism can be isolated from stool & sputum?

Accepted Answer

Paragonimus

Answer

Fasciola

Answer

P. carinii

Answer

Clonorchis

Question 5

Largest intestinal protozoan is?

Accepted Answer

Balantidium coli

Answer

E. coli

Answer

Giardia

Answer

T. gondii

Question 6

Which type of malaria is most commonly associated with renal failure?

Accepted Answer

Falciparum

Answer

Vivax

Answer

Malariae

Answer

Ovale

Question 7

What is the most common protozoan associated with keratitis?

Accepted Answer

Acanthamoeba

Answer

Plasmodium

Answer

Toxoplasma

Answer

Entamoeba histolytica

Question 8

Flame cells are primarily associated with which of the following organisms?

Accepted Answer

Trematodes

Answer

Protozoa

Answer

Nematodes

Answer

None of the options

Question 9

Cercariae are the infective form of which of the following parasites?

Accepted Answer

Schistosoma hematobium

Answer

Paragonimus westermani

Answer

Fasciola hepatica

Answer

Taenia solium

Question 10

Unsegmented eggs are in which parasite?

Accepted Answer

Trichuris trichiura

Answer

Ancylostoma

Answer

Necator americanus

Answer

Dracunculus

Parasitology — MCQs

Parasitology — MCQs

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