Parasitology Practice Questions

Q: What does the hookworm primarily feed on?

Blood from intestinal mucosa. ***Blood from intestinal mucosa*** - Hookworms attach to the **intestinal wall** and ingest host blood, leading to blood loss and potential **anemia**. - They produce **anticoagulants** to facilitate continuous feeding from the mucosal capillaries. *Plasma proteins* - While plasma contains proteins, hookworms primarily feed directly on **whole blood**, not just isolated plasma proteins. - Feeding mainly on plasma proteins would not explain the significant **iron-deficiency anemia** associated with hookworm infection. *Lymphatic fluid* - Hookworms reside in the **small intestine** and do not typically feed on lymphatic fluid. - Other parasites, like **filarial worms**, are known to inhabit and obstruct the lymphatic system. *Interstitial fluid* - Interstitial fluid is found in the spaces between cells; hookworms feed from the **vascular supply** within the intestinal mucosa. - Feeding on interstitial fluid would not cause the characteristic **blood loss** seen in hookworm infections.

Q: Infective form of Hookworms?

Filariform larva. ***Filariform larva*** - The **filariform larva (L3)** is the infective stage of hookworms, capable of penetrating intact skin. - Upon penetration, these larvae migrate through the bloodstream to the lungs, then up the bronchial tree to be swallowed, eventually maturing in the intestines. *Egg* - Hookworm **eggs** are passed in the feces of infected individuals and are not infective to humans directly. - They require favorable conditions (warm, moist soil) to embryonate and hatch into rhabditiform larvae. *Rhabditiform larva* - The **rhabditiform larva (L1)** is the first larval stage that hatches from the egg in the soil. - It is a non-infective, free-living stage that feeds on bacteria and molts twice to become the infective filariform larva. *Adult worm* - **Adult worms** reside in the small intestine of the host and are not the infective form. - They attach to the intestinal mucosa and feed on blood, causing the characteristic anemia associated with hookworm infection.

Q: Which Schistosoma species is primarily associated with eggs being discharged in urine?

S. haematobium. ***S. haematobium*** - *S. haematobium* specifically targets the **urinary bladder plexus**, leading to the discharge of eggs in the **urine**. - Infection with *S. haematobium* is the primary cause of **urinary schistosomiasis** and is associated with complications like **hematuria** and bladder cancer. *S. japonicum (intestinal)* - *S. japonicum* primarily infects the **mesenteric veins of the small intestine** and discharges its eggs in **feces**, not urine. - This species is known for causing severe **intestinal and hepatic schistosomiasis** due to the large number of eggs produced. *S. mansoni (intestinal)* - *S. mansoni* also primarily infects the **mesenteric veins, mainly of the large intestine**, and its eggs are excreted in **feces**. - It is a common cause of **intestinal schistosomiasis**, leading to symptoms such as abdominal pain, diarrhea, and hepatosplenomegaly. *S. mekongi* - *S. mekongi* is another **intestinal schistosome**, closely related to *S. japonicum*, and its eggs are discharged in **feces**. - This species is found in specific regions of Southeast Asia and causes similar symptoms to other intestinal schistosomes.

Q: Consumption of uncooked pork is likely to cause which of the following helminthic disease -

Taenia solium. ***Taenia solium*** - Infection with **_Taenia solium_** (pork tapeworm) occurs by consuming raw or undercooked **pork** containing **cysticerci** (larval cysts). - This can lead to **taeniasis** (intestinal tapeworm infection) and, if humans ingest the eggs, **cysticercosis**, a more severe disease involving larval cysts in tissues like the brain. *Taenia saginata* - **_Taenia saginata_** (beef tapeworm) is acquired by eating raw or undercooked **beef** containing larval cysts, not pork. - While it causes gastrointestinal symptoms, it does not typically lead to systemic cysticercosis in humans. *Trichuris trichiura* - **_Trichuris trichiura_** (whipworm) infection is caused by ingesting **embryonated eggs** from contaminated soil, typically associated with poor sanitation. - It is not transmitted through the consumption of undercooked meat. *None of the options* - This option is incorrect because **_Taenia solium_** is definitively associated with the consumption of uncooked pork.

Q: Amoebic liver abscess can be diagnosed by demonstrating-

Trophozoites in the pus. ***Trophozoites in the pus*** - **Amoebic liver abscesses** are caused by the invasive **trophozoite stage** of *Entamoeba histolytica*. - Demonstrating **trophozoites** in the characteristic **'anchovy paste' pus** aspirated from the abscess cavity is diagnostic. *Cysts in the pus* - **Cysts** are the **infective stage** of *Entamoeba histolytica* and are typically found in the **feces**, not in an abscess. - Cysts are responsible for transmission and survival outside the host, but they do not cause invasive disease. *Cysts in the liver* - The disease in the liver is caused by **trophozoites**, which invade the intestinal wall and then spread to the liver. - **Cysts** are never found within the liver parenchyma or abscesses. *Trophozoites in the feces* - While **trophozoites** can be found in the feces during acute amoebic dysentery, their presence alone does not confirm a liver abscess. - Furthermore, **trophozoites** are fragile and often difficult to detect in stool samples, especially once the stool has cooled.

Q: Cutaneous larva migrans is due to ?

Ancylostoma braziliense. ***Ancylostoma braziliense*** - **Cutaneous larva migrans** is primarily caused by the larvae of **dog and cat hookworms**, especially *Ancylostoma braziliense*. - Humans become **accidental hosts** when these larvae penetrate the skin but cannot complete their life cycle, leading to **serpiginous tracks**. *W. bancrofti* - This parasite, **Wuchereria bancrofti**, is a filarial nematode that causes **lymphatic filariasis** (elephantiasis). - Its effects are characterized by **lymphedema** and **hydrocele**, not migrating skin lesions. *B. Malayi* - **Brugia malayi** is another filarial nematode responsible for **lymphatic filariasis** in humans, similar to *W. bancrofti*. - It primarily causes **swelling of the limbs** and scrotum, not cutaneous larva migrans. *D. medinensis* - **Dracunculus medinensis** is the parasite that causes **dracunculiasis**, also known as **Guinea worm disease**. - This infection is characterized by a **painful blister** and subsequent emergence of the adult worm, which is distinct from creeping eruptions.

Q: Which of the following statements about malaria transmission is correct?

Individuals harboring gametocytes can transmit malaria.. ***Individuals harboring gametocytes can transmit malaria.*** - **Gametocytes** are the sexual stage of the malaria parasite that circulate in the human bloodstream and are infectious to mosquitos. - When an *Anopheles* mosquito feeds on an infected human, it ingests these gametocytes, allowing the parasite's life cycle to continue in the mosquito vector, leading to transmission. *P. vivax always completely fills the infected RBC with schizonts.* - While *P. vivax* does infect **reticulocytes** (young RBCs) and can enlarge them, the **schizonts** typically occupy a significant portion but not always completely fill the host cell. - The infected RBCs are often enlarged to about 1.5 to 2 times their normal size and contain numerous **Schüffner's dots**. *Malaria can only be transmitted through blood transfusions.* - The primary mode of malaria transmission is through the bite of an **infected female *Anopheles* mosquito**. - While **blood transfusions** can transmit malaria, it is a less common and secondary route compared to vector-borne transmission. *All stages of P. falciparum are commonly seen in peripheral blood smears.* - In *P. falciparum* infections, only the **ring forms** and **gametocytes** are commonly observed in the peripheral blood smear. - The more mature asexual stages (trophozoites and schizonts) typically sequester in the capillaries of internal organs, where they are not readily visible in peripheral circulation.

Q: Which of the following amoebae does not have a neuropathogenic effect?

Dientamoeba. ***Dientamoeba*** - *Dientamoeba fragilis* is an intestinal flagellate (often mistakenly classified as an amoeba) that causes **gastrointestinal symptoms** like diarrhea and abdominal pain. - It has **no known neuropathogenic effects** and does not invade the central nervous system. *Naegleria* - *Naegleria fowleri* is a highly virulent amoeba that causes **primary amoebic meningoencephalitis (PAM)**, a rapidly fatal infection of the central nervous system. - It typically invades the brain after **nasal insufflation** of contaminated water. *Acanthamoeba* - *Acanthamoeba* species can cause **granulomatous amoebic encephalitis (GAE)**, a subacute to chronic central nervous system infection, particularly in immunocompromised individuals. - They are also known to cause **amoebic keratitis**, a severe eye infection. *Balamuthia* - *Balamuthia mandrillaris* causes **granulomatous amoebic encephalitis (GAE)**, similar to *Acanthamoeba*, but often in both immunocompetent and immunocompromised individuals. - It can also lead to **skin lesions** and has a tropism for the brain, causing severe neurological damage.

Q: Cylindrical helminths are -

Roundworms. ***Roundworms*** - **Roundworms**, also known as **nematodes**, are characterized by their **cylindrical body shape**. - Their unsegmented, tapered bodies distinguish them from flatworms like tapeworms and flukes. *Tapeworms* - **Tapeworms**, or **cestodes**, have **flat, ribbon-like bodies** segmented into proglottids. - They are not cylindrical but rather dorsoventrally flattened. *Flukes* - **Flukes**, or **trematodes**, have **flat, leaf-shaped bodies**, which are not cylindrical. - Their morphology includes suckers for attachment and they are not segmented. *Hookworms* - **Hookworms** are a type of **roundworm** (nematode), which means they are cylindrical. However, "Roundworms" is a broader and more accurate classification for the general term "cylindrical helminths." - While hookworms are indeed cylindrical, the option "Roundworms" encompasses all such cylindrical helminths, making it a more general and appropriate answer.

Q: In malaria, pre-erythrocytic schizogony occurs in -

Liver. ***Liver*** - After being introduced by a mosquito bite, **Plasmodium sporozoites** rapidly travel to the liver - In the liver, they invade **hepatocytes** and undergo asexual reproduction, known as **pre-erythrocytic (or hepatic) schizogony**, forming merozoites - This is the exo-erythrocytic cycle that occurs before red blood cell invasion *Lung* - The lungs are not a primary site for **Plasmodium** development or asexual reproduction in the human host - While some parasite components or host immune responses might involve the lungs in severe malaria, it is not where pre-erythrocytic schizogony occurs *Spleen* - The **spleen** is primarily involved in clearing infected red blood cells and acts as a site for immune responses to malaria, but not for initial schizogony - It plays a significant role in the **erythrocytic stage** of malaria by filtering and destroying parasitized red blood cells *Kidney* - The **kidneys** are not involved in the life cycle of the **Plasmodium parasite** during pre-erythrocytic schizogony - While malaria can cause **renal complications** (such as acute kidney injury in severe cases), this is a pathological effect, not a site of parasite development

Question 1

What does the hookworm primarily feed on?

Accepted Answer

Blood from intestinal mucosa

Answer

Plasma proteins

Answer

Lymphatic fluid

Answer

Interstitial fluid

Question 2

Infective form of Hookworms?

Accepted Answer

Filariform larva

Answer

Egg

Answer

Rhabditiform larva

Answer

Adult worm

Question 3

Which Schistosoma species is primarily associated with eggs being discharged in urine?

Accepted Answer

S. haematobium

Answer

S. japonicum

Answer

S. mansoni

Answer

S. mekongi

Question 4

Consumption of uncooked pork is likely to cause which of the following helminthic disease -

Accepted Answer

Taenia solium

Answer

Taenia saginata

Answer

Trichuris trichiura

Answer

None of the options

Question 5

Amoebic liver abscess can be diagnosed by demonstrating-

Accepted Answer

Trophozoites in the pus

Answer

Trophozoites in the feces

Answer

Cysts in the pus

Answer

Cysts in the liver

Question 6

Cutaneous larva migrans is due to ?

Accepted Answer

Ancylostoma braziliense

Answer

W.bancrofti

Answer

B. Malayi

Answer

D. medinensis

Question 7

Which of the following statements about malaria transmission is correct?

Accepted Answer

Individuals harboring gametocytes can transmit malaria.

Answer

P. vivax always completely fills the infected RBC with schizonts.

Answer

Malaria can only be transmitted through blood transfusions.

Answer

All stages of P. falciparum are commonly seen in peripheral blood smears.

Question 8

Which of the following amoebae does not have a neuropathogenic effect?

Accepted Answer

Dientamoeba

Answer

Naegleria

Answer

Acanthamoeba

Answer

Balamuthia

Question 9

Cylindrical helminths are -

Accepted Answer

Roundworms

Answer

Tapeworms

Answer

Flukes

Answer

Hookworms

Question 10

In malaria, pre-erythrocytic schizogony occurs in -

Accepted Answer

Liver

Answer

Lung

Answer

Spleen

Answer

Kidney

Parasitology — MCQs

Parasitology — MCQs

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