Parasitology Practice Questions

Q: Which of the following is correct about the image shown?

Dracunculus. ***Dracunculus*** - The image shows a procedure for extracting a **guinea worm (Dracunculus medinensis)** by gradually winding it around a stick. - This characteristic method of removal is pathognomonic for **dracunculiasis**. *Cutaneous Larva migrans* - This condition presents as **serpiginous, erythematous, pruritic tracks** on the skin, caused by hookworm larvae. - It does not involve a visible worm being extracted with a stick. *Visceral larva migrans* - This is caused by the migration of nematode larvae (typically *Toxocara canis* or *cati*) through internal organs, with systemic symptoms. - It does not manifest as a worm emerging from a skin lesion. *Tenia solium* - *Taenia solium* (pork tapeworm) infection can manifest as taeniasis (intestinal infection) or **cysticercosis** (larval cysts in tissues). - Neither of these presentations involves a worm being manually extracted from a skin lesion in this manner.

Q: The following diagram depicts blood smear of which species?

Plasmodium falciparum. ***Plasmodium falciparum*** - The image displays characteristic **crescent-shaped or banana-shaped gametocytes** (stages 16-20), which are **pathognomonic for *Plasmodium falciparum*** - The earlier stages (1-5) represent ring forms (multiple rings per RBC, delicate ring forms) - Subsequent stages (6-15) show maturation culminating in the distinct **crescentic gametocytes** - This morphology is the **key distinguishing feature** of P. falciparum *Plasmodium vivax* - Produces **oval-shaped gametocytes**, not crescent-shaped - Characterized by enlarged RBCs with **Schüffner's dots** - Shows amoeboid trophozoites, not seen in this smear *Plasmodium malariae* - Produces **oval to round gametocytes** - Characteristic **band forms** and **rosette-shaped schizonts** (8-12 merozoites) - Not crescent-shaped as shown in the image *Plasmodium ovale* - Produces **oval gametocytes** similar to P. vivax - RBCs show **fimbriated edges** and Schüffner's dots - Does not produce crescent-shaped gametocytes

Q: A 20-year-old lady presents with high grade fever and incoherent talking for 1 day. The following peripheral smear shows presence of:

Gametocyte. ***Gametocyte*** - The image clearly shows a **crescent-shaped** parasite within a red blood cell, which is characteristic of the **gametocytes of *Plasmodium falciparum***. - The patient's symptoms of **high-grade fever** and **non-coherent talking** (suggesting cerebral malaria) are consistent with severe *P. falciparum* infection, where gametocytes are often seen on peripheral smears. *Sporozoite* - Sporozoites are the **infectious forms of malaria parasites** transmitted from the mosquito to humans; they are typically found in the **salivary glands of mosquitoes** and briefly in human blood before infecting liver cells. - They are generally **not observed in peripheral blood smears** during the symptomatic phase of malaria. *Merozoite* - Merozoites are the forms that emerge from **infected liver cells** and then subsequently from **infected red blood cells** to invade new red blood cells, thus perpetuating the asexual cycle. - They are very **short-lived extracellularly** and are rarely seen in peripheral blood smears; instead, **ring forms, trophozoites, and schizonts** (representing asexual stages) are typically observed inside red blood cells. *Schistocyte* - Schistocytes are **fragmented red blood cells** that result from **mechanical damage** to red blood cells, often seen in conditions like microangiopathic hemolytic anemia or disseminated intravascular coagulation. - They are not a life stage of the malaria parasite; their presence would indicate a co-existing or secondary hematological issue, not a parasitic form.

Q: The image shows presence of:

Giardia lamblia. ***Giardia lamblia*** - The image clearly displays a **pyriform (pear-shaped)** organism with **two nuclei** and a "smiley face" appearance due to the location of the nuclei, characteristic of *Giardia lamblia* trophozoites. - The presence of **flagella** (typically 4 pairs) and the **ventral sucking disc** are distinguishing features of *Giardia lamblia* trophozoites. - *Giardia* is commonly found in duodenal aspirates and stool samples, causing giardiasis with symptoms of malabsorption and diarrhea. *Entamoeba histolytica* - *Entamoeba histolytica* trophozoites are typically **amoeboid** in shape with unidirectional movement, not pear-shaped. - They usually contain a **single nucleus** with central karyosome and peripheral chromatin. - They may show **ingested red blood cells** within their cytoplasm, which is not seen here. *Balantidium coli* - *Balantidium coli* trophozoites are very large (50-100 μm), **oval-shaped ciliates** with a prominent **macronucleus** (kidney-shaped) and a smaller micronucleus. - The entire surface is **covered with cilia** giving a characteristic appearance, which is not seen in this image. *Trichomonas vaginalis* - *Trichomonas vaginalis* trophozoites are also **pear-shaped with flagella** (typically 4 anterior flagella), but have only **one nucleus** located anteriorly. - They possess an **undulating membrane** and a posterior axostyle that extends beyond the cell body. - The presence of **two nuclei** and the bilateral symmetry seen in this image are characteristic of *Giardia*, not *Trichomonas*.

Q: The following image shows presence of:

Entamoeba histolytica. ***Entamoeba histolytica*** - The image shows a **cyst with multiple nuclei** (typically 1-4, but can be more in stained preparations) and a **central karyosome** within each nucleus, which are characteristic features of *Entamoeba histolytica* cysts. - The presence of **refractile chromatoid bodies** with rounded ends can also be seen in *Entamoeba histolytica* cysts (though not distinctly visible in this specific stain, the overall morphology with multiple nuclei is key). *Giardia lamblia* - *Giardia lamblia* cysts are **oval or pear-shaped** and typically have **four nuclei** clustered at one end, along with visible **flagella remnants** and a median body, which are not present in the image. - The overall shape and nuclear arrangement do not match the morphology of *Giardia lamblia* cysts. *Balantidium coli* - *Balantidium coli* are significantly **larger** than *Entamoeba* cysts and possess a distinct **macronucleus** (kidney-shaped) and a smaller **micronucleus**, often with easily visible **cilia** on their surface in the trophozoite stage. - The size and nuclear structure in the image are inconsistent with *Balantidium coli*. *Entamoeba coli* - *Entamoeba coli* is a **non-pathogenic commensal amoeba** that can be confused with *E. histolytica*. However, *E. coli* cysts typically have **more than 4 nuclei** (often 8 or more in mature cysts) with **eccentric karyosomes** (not central). - The cysts also have **chromatoid bodies with splintered or irregular ends** (unlike the smooth, rounded ends in *E. histolytica*). - The nuclear morphology and count in the image are more consistent with *E. histolytica* than *E. coli*.

Q: The following image shows presence of:

Taenia solium. ***Taenia solium*** - The image shows the **scolex** (head) of a parasitic worm with both **suckers** (bottom arrow) and a prominent **rostellum with hooks** (top arrow), which is characteristic of *Taenia solium* (pork tapeworm). - The presence of the armed rostellum differentiates *Taenia solium* from *Taenia saginata*, which only has suckers. *Necator americanus* - This is a **hookworm** and its mouthparts typically feature **cutting plates**, not suckers and hooks in the manner shown. - Hookworms are nematodes, distinct from the cestode morphology presented. *Ancylostoma duodenale* - Similar to *Necator americanus*, *Ancylostoma duodenale* is also a **hookworm** and possesses **teeth** in its buccal capsule, not the distinct suckers and rostellum with hooks seen in the image. - Again, this morphology is inconsistent with a cestode. *Enterobius vermicularis* - This is a **pinworm**, a small nematode, and its anterior end does not feature the prominent scolex with suckers and a hooked rostellum visible in the image. - *Enterobius vermicularis* has a more simple mouth, sometimes with cuticular alae.

Q: Which of the following worms is shown in the specimen?

Ascaris lumbricoides. ***Ascaris lumbricoides*** - The image displays a collection of **large, creamy-white to yellowish-brown, roundworms** that are characteristic of *Ascaris lumbricoides*. These worms are often referred to as **giant roundworms** due to their size. - They are typically found in the **intestines** and can grow up to 35 cm in length, which is consistent with the appearance of the worms in the specimen jar. *Trichinella* - *Trichinella* species are **much smaller** and are typically not visible as macroscopic worms in a specimen jar in this manner. - They are primarily known for causing **trichinellosis**, where larvae encyst in muscle tissue, rather than forming large masses in the intestines. *Wuchereria bancrofti* - *Wuchereria bancrofti* causes **lymphatic filariasis** and its adult worms reside in the lymphatic system. - These worms are **thin and thread-like** and are generally much smaller and more delicate than the worms shown in the specimen, which appear robust. *Trichuris trichiura* - *Trichuris trichiura*, also known as **whipworm**, has a characteristic **whip-like appearance** with a thin anterior portion and a thicker posterior end. - While they are intestinal nematodes, they are generally **smaller** and have a distinct morphology not seen in the specimen.

Q: Which of the following eggs is seen in stool microscope examination?

Trichuris trichiura. ***Trichuris trichiura (whipworm) egg*** - The image displays a **barrel-shaped egg** with prominent, translucent **polar plugs (mucous plugs)** at each end, which is characteristic of *Trichuris trichiura* (whipworm) - These eggs measure approximately **50-54 × 22-23 μm** and have a thick, smooth shell with characteristic bipolar plugs - Found in **stool samples** during microscopic examination, indicating whipworm infection *Ascaris lumbricoides* - Eggs are **oval/round** (45-75 × 35-50 μm), not barrel-shaped - Have a thick, mammillated (bumpy) outer coat when unfertilized, or smooth when fertilized - **No polar plugs** - this is the key differentiating feature *Enterobius vermicularis* - Eggs are **asymmetrically oval** and flattened on one side (50-60 × 20-30 μm) - **No polar plugs** present - Rarely seen in stool; best detected by **perianal scotch tape test** *Taenia species* - Eggs are **spherical** (30-40 μm diameter) with radial striations - Contain a **six-hooked embryo (hexacanth)** inside - **No polar plugs** and completely different morphology

Q: Which of the following is shown here?

To answer the question "Which of the following is shown here?", I need the actual options. The provided JSON has an empty `options` array. Without the options, I cannot definitively explain which one is correct or incorrect. However, based on the image provided: The image displays a **microscopic view of an egg** (likely parasitic, given the context of medical questions) next to a **labeled diagram of the same egg**. Key features visible in both the micrograph and the diagram include: - An **ovoid shape**. - A **hyaline shell** (outer layer). - A **clear space** between the shell and the internal contents. - Internal contents showing **blastomeres**, indicating a developing embryo. This morphology is characteristic of a **hookworm egg** (e.g., *Ancylostoma duodenale* or *Necator americanus*). Hookworm eggs are typically oval, have a thin, smooth shell, and often contain a developing embryo with 2-8 blastomeres when passed in fresh stool. If you provide the options, I can formulate the explanation according to the specified markdown format.

Q: The image shown below shows egg of? (AIIMS May 2017)

A. lumbricoides. ***A. lumbricoides*** - The image displays a **mammillated outer layer** and an **oval shape**, characteristic features of a fertilized *Ascaris lumbricoides* egg. - The internal content shows a **developing embryo** (morula stage), which is typical for newly passed *Ascaris* eggs. *A. duodenale* - The eggs of *Ancylostoma duodenale* (hookworm) are typically **oval or ellipsoidal**, have a **thin, transparent shell**, and contain a **segmented ovum** (usually 2-8 cells) when passed in stool. - They lack the distinctive **thick, mammillated outer layer** seen in the image. *E. vermicularis* - *Enterobius vermicularis* (pinworm) eggs are **D-shaped** or **asymmetrically ovoid**, with one side flattened. - They possess a **thin, smooth shell** and contain a **larva**, which distinguishes them from the egg shown. *Strongyloides stercoralis* - *Strongyloides stercoralis* eggs are rarely seen in stool samples because they usually **hatch within the intestine**, releasing **rhabditiform larvae**. - When present, they are **oval, thin-shelled**, and contain a **partially developed larva**.

Question 1

Which of the following is correct about the image shown?

Accepted Answer

Dracunculus

Answer

Cutaneous Larva migrans

Answer

Visceral larva migrans

Answer

Tenia solium

Question 2

The following diagram depicts blood smear of which species?

Accepted Answer

Plasmodium falciparum

Answer

Plasmodium malariae

Answer

Plasmodium ovale

Answer

Plasmodium vivax

Question 3

A 20-year-old lady presents with high grade fever and incoherent talking for 1 day. The following peripheral smear shows presence of:

Accepted Answer

Gametocyte

Answer

Sporozoite

Answer

Merozoite

Answer

Schistocyte

Question 4

The image shows presence of:

Accepted Answer

Giardia lamblia

Answer

Entamoeba histolytica

Answer

Balantidium coli

Answer

Trichomonas vaginalis

Question 5

The following image shows presence of:

Accepted Answer

Entamoeba histolytica

Answer

Giardia lamblia

Answer

Balantidium coli

Answer

Entamoeba coli

Question 6

The following image shows presence of:

Accepted Answer

Taenia solium

Answer

Necator americanus

Answer

Ancylostoma duodenale

Answer

Enterobius vermicularis

Question 7

Which of the following worms is shown in the specimen?

Accepted Answer

Ascaris lumbricoides

Answer

Trichinella

Answer

Wuchereria bancrofti

Answer

Trichuris trichiura

Question 8

Which of the following eggs is seen in stool microscope examination?

Accepted Answer

Trichuris trichiura

Answer

Taenia species

Answer

Ascaris lumbricoides

Answer

Enterobius vermicularis

Question 9

Which of the following is shown here?

Question 10

The image shown below shows egg of? (AIIMS May 2017)

Accepted Answer

A. lumbricoides

Answer

A. duodenale

Answer

E. vermicularis

Answer

Strongyloides stercoralis

Parasitology — MCQs

Parasitology — MCQs

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