Parasitology Practice Questions

Q: All of the following helps in the diagnosis of leishmaniasis except:

Immobilisation test. ***Immobilisation test*** - The **immobilisation test** is used to detect antibodies that inhibit the motility of organisms like *Trypanosoma cruzi* (Chagas disease), not *Leishmania*. - This test is not relevant for the diagnosis of leishmaniasis, as it targets a different parasitic mobility mechanism. *Examination of the bone marrow* - **Bone marrow aspiration** is a highly sensitive and specific method for diagnosing visceral leishmaniasis because **amastigotes** of *Leishmania* parasites are found intracellularly within macrophages in the bone marrow. - Direct visualization of the parasites in bone marrow smears confirms the diagnosis. *Blood smear* - While generally less sensitive than bone marrow aspiration, a **peripheral blood smear** can occasionally reveal **amastigotes** in circulating monocytes during the acute phase of visceral leishmaniasis. - However, its diagnostic utility is limited as the parasitic load in peripheral blood is often low. *Aldehyde test* - The **formol gel test** (also known as the **aldehyde test** or Napier's aldehyde test) is a non-specific test for **hypergammaglobulinemia**, which is a common finding in long-standing visceral leishmaniasis. - A positive result (gelation of serum after adding formaldehyde) suggests chronic infection but does not specifically confirm leishmaniasis nor differentiate it from other chronic inflammatory conditions.

Q: Which of the following parasite infections predispose to malignancies? (Select all that apply)

Schistosomiasis. Schistosomiasis - Chronic infection with *Schistosoma haematobium* is a major risk factor for developing **squamous cell carcinoma of the bladder**. [1] - The parasite's eggs deposited in the bladder wall induce chronic inflammation, cell proliferation, and ultimately **neoplastic transformation**. *Clonorchiasis* - Caused by *Clonorchis sinensis* (the Chinese liver fluke), which is strongly associated with **cholangiocarcinoma** (bile duct cancer). - Chronic inflammation and mechanical irritation from the flukes in the bile ducts lead to epithelial hyperplasia and, eventually, malignant changes. *Guinea worm infection* - Caused by *Dracunculus medinensis*, which primarily causes painful skin lesions and ulcers as the adult worm emerges. - While it causes significant morbidity, there is **no known association** with an increased risk of malignancy. *Paragonimus westermani* - This lung fluke causes paragonimiasis, leading to chronic inflammation and granuloma formation in the lungs, mimicking tuberculosis. - Although it causes severe pathology, there is **no well-established link** between *Paragonimus westermani* infection and the development of malignancy.

Q: 18 years old male developed meningitis 5 days after taking a bath in a pond. The likely causative organism -

Naegleria fowleri. ***Naegleria fowleri*** - This amoeba is known to cause **primary amoebic meningoencephalitis (PAM)**, a rapidly fatal brain infection. - Infection typically occurs when individuals swim in **warm fresh water**, such as ponds or lakes, allowing the amoeba to enter the brain via the nasal passages. - The **incubation period is typically 1-9 days** (commonly around 5 days), which matches the clinical timeline in this case. *Cryptococcus* - **Cryptococcal meningitis** is an opportunistic infection typically seen in immunocompromised individuals, such as those with HIV/AIDS. - It is usually acquired by inhaling fungal spores from the environment, not directly from swimming in ponds. *Enterococcus* - **Enterococcus** is a bacterium that can cause meningitis, particularly in neonates, the elderly, or those with underlying medical conditions or hospital-acquired infections. - It is not typically associated with exposure to pond water as a primary risk factor for meningitis. *Meningococcus* - **Neisseria meningitidis (Meningococcus)** is a common bacterial cause of meningitis, often transmitted person-to-person through respiratory droplets. - While it causes meningitis, its transmission is not linked to swimming in ponds.

Q: A pregnant lady had no complaints but mild cervical lymphadenopathy in first trimester. She was prescribed spiramycin but she was noncompliant. Baby was born with hydrocephalus and intracerebral calcification. Which of these is likely cause ?

Toxoplasmosis. ***Toxoplasmosis*** - The combination of **hydrocephalus** and **intracerebral calcifications** in a newborn is highly characteristic of **congenital toxoplasmosis**. The mother's mild cervical lymphadenopathy in the first trimester, coupled with non-compliance to spiramycin (an agent used to limit vertical transmission), further supports this diagnosis. - While many maternal infections are asymptomatic, fetal infection can lead to severe consequences. **Spiramycin** is used to reduce the risk of transplacental transmission, but does not treat established fetal infection. *CMV* - **Congenital cytomegalovirus (CMV)** can also cause **intracerebral calcifications**, but these are typically **periventricular**, unlike the diffuse calcifications seen in toxoplasmosis. - CMV often presents with **microcephaly** rather than hydrocephalus, and can also involve symptoms like **sensorineural hearing loss** and hepatosplenomegaly. *Rubella* - **Congenital rubella syndrome** is characterized by the classic triad of **cataracts**, **sensorineural hearing loss**, and **congenital heart defects** (e.g., patent ductus arteriosus). - While it can cause some central nervous system abnormalities, **hydrocephalus** and **intracerebral calcifications** are not its primary or characteristic presentation. *Herpes* - **Congenital herpes simplex virus (HSV) infection** typically presents with skin vesicles, keratitis, and encephalitis. - While it can cause neurological complications, **hydrocephalus** and prominent **intracerebral calcifications** similar to those described are not the hallmark features.

Q: All of the following are known to cause biliary obstruction EXCEPT:

Ancylostoma. ***Ancylostoma*** - **Ancylostoma**, or **hookworm**, primarily infects the small intestine, causing **iron deficiency anemia** due to blood loss. - It does not directly obstruct the biliary tree as it does not migrate there. *Fasciola* - **Fasciola hepatica**, the **sheep liver fluke**, can migrate to the **biliary ducts** and cause inflammation, fibrosis, and obstruction. - Its presence can lead to **cholangitis**, **cholecystitis**, and **formation of gallstones**. *Ascariasis* - **Ascaris lumbricoides**, a large intestinal nematode, can **migrate from the gut** into the **biliary tree** through the ampulla of Vater. - This can cause **acute cholangitis**, **pancreatitis**, or even **biliary obstruction** due to the physical presence of the worms. *Clonorchis* - **Clonorchis sinensis**, the **Chinese liver fluke**, specifically inhabits the **biliary ducts** of its human host. - Chronic infection can lead to profound **biliary obstruction**, **cholangitis**, and is a significant risk factor for **cholangiocarcinoma**.

Q: Brain abscess in immunodeficient person is due to :

Toxoplasma gondii. ***Toxoplasma gondii*** - **Toxoplasma gondii** is a very common cause of **brain abscesses** (cerebral toxoplasmosis) in individuals with compromised immune systems, especially those with AIDS. - The parasite is usually latent in many people and reactivates when the immune system weakens. *Aspergillus* - While *Aspergillus* can cause central nervous system infections, including brain abscesses, this is usually seen in severely **neutropenic** or transplant patients. - *Aspergillus* typically invades via **hematogenous spread** from a primary pulmonary infection or directly from sinusitis. *Cryptococcus* - *Cryptococcus neoformans* is a significant cause of **meningitis** in immunocompromised patients, particularly those with HIV/AIDS. - While it can cause **cryptococcomas** (focal lesions), pure abscess formation is less common than with *Toxoplasma*. *Candida* - *Candida* species can cause **brain microabscesses** or multifocal lesions, especially in patients with disseminated candidiasis originating from prolonged hospitalization or indwelling catheters. - However, large, solitary brain abscesses are less typical for *Candida* compared to *Toxoplasma gondii*.

Q: Cyclops play an important role in the transmission of:

Dracunculiasis. ***Dracunculiasis*** - **Cyclops** (copepods) are the intermediate hosts for the guinea worm (**Dracunculus medinensis**), the causative agent of **dracunculiasis**. - Humans become infected by drinking water containing Cyclops that have ingested **Dracunculus larvae**. *Typhoid* - Typhoid fever is caused by **Salmonella typhi** and is transmitted through **feco-oral contamination** of food and water. - It does not involve Cyclops or any insect intermediate host in its transmission cycle. *Ancylostomiasis* - **Ancylostomiasis** (hookworm infection) is caused by **Ancylostoma duodenale** or **Necator americanus**. - Transmission occurs when **larvae penetrate the skin**, typically from contaminated soil, not through Cyclops. *Yellow fever* - Yellow fever is a viral disease transmitted to humans primarily through the bite of infected **Aedes mosquitoes**. - Cyclops are not involved in the transmission of this arbovirus.

Q: Diarrhea syndrome in an AIDS patient can be due to which of the following? a) Rota virus b) Cryptosporidium c) Adenovirus d) E. coli

Cryptosporidium. ***Cryptosporidium*** - **Cryptosporidium parvum** is a common cause of **chronic, severe, watery diarrhea** in AIDS patients due to their compromised immune system [1]. - Infection can lead to **malabsorption** and significant weight loss in immunocompromised individuals [1]. *Adenovirus* - While adenoviruses can cause **gastroenteritis**, particularly in children, they are generally not a primary cause of severe, chronic diarrhea in AIDS patients. - Other opportunistic pathogens are usually more prevalent and cause more severe disease in immunocompromised hosts. *Rota virus* - **Rotavirus** is a common cause of **acute gastroenteritis** in infants and young children worldwide. - While it can infect immunocompromised individuals, it typically causes self-limiting illness and is less likely than Cryptosporidium to cause persistent, severe diarrhea in AIDS patients. *E. coli* - Various strains of **Escherichia coli** can cause diarrhea, ranging from traveler's diarrhea (e.g., ETEC) to hemorrhagic colitis (e.g., EHEC). - While some E. coli infections can be severe, they are not specifically or predominantly linked to chronic diarrhea in AIDS patients in the way opportunistic pathogens like Cryptosporidium are.

Q: In a rural clinic, a 3-year-old girl child is brought by her mother and is emaciated. Her hemoglobin was 5 g/dL. The girl also has edema over her knees and ankles with discrete rash on her knees, ankles and elbows. The most likely worm infestation causing these manifestations is:

Hookworm. ***Hookworm*** - **Hookworm infection** (Ancylostoma duodenale/Necator americanus) leads to chronic blood loss from the intestines, causing **microcytic hypochromic anemia** and **severe emaciation** due to persistent nutrient loss and malabsorption. - The combination of severe **anemia (Hb 5 g/dL)**, **emaciation**, and **edema** (due to **hypoalbuminemia**, a consequence of protein-losing enteropathy and poor nutrition) is highly characteristic of hookworm infestation in children. - The **discrete rash** on pressure points (knees, ankles, elbows) may represent **ground itch** (pruritic papulovesicular rash at larval penetration sites) or dermatitis secondary to malnutrition and edema. *Roundworm* - **Ascaris lumbricoides** can cause malnutrition and growth delays, but typically does not lead to the severe anemia and edema seen here unless there is a massive infestation leading to intestinal obstruction or biliary obstruction. - Its primary impact is often related to **nutrient competition** and mechanical obstruction, not significant blood loss. *Pinworm* - **Enterobius vermicularis** (pinworm) infection primarily causes **perianal itching**, especially at night. - It does not typically cause systemic symptoms like **severe anemia**, **emaciation**, or **edema**, as it does not feed on blood or cause significant nutrient malabsorption. *Whipworm* - **Trichuris trichiura** (whipworm) can cause chronic dysentery, **rectal prolapse**, and **anemia** in heavy infections due to blood loss. - While it can contribute to **growth retardation** and anemia, it is less likely to cause the profound emaciation and edema described compared to hookworm, especially with a hemoglobin level of 5 g/dL, which points strongly to major chronic blood loss.

Q: The spike of fever in malaria is at the time of release of ?

Merozoites. ***Merozoites*** - The **fever spikes** characteristic of malaria coincide with the synchronized **rupture of infected red blood cells** [1] and the release of new **merozoites** into the bloodstream. - These released merozoites then invade new red blood cells [1], continuing the cycle and triggering the host's inflammatory response, leading to fever. *Sporozoites* - **Sporozoites** are the forms injected by the mosquito into the human host and travel to the liver. - Their release from infected liver cells as **merozoites** into the bloodstream does not directly cause the characteristic fever spikes. *Hypnozoites* - **Hypnozoites** are dormant forms of *Plasmodium vivax* and *P. ovale* that persist in the liver and are responsible for **relapses** [1] weeks or months after the initial infection. - They do not directly cause the acute fever spikes associated with the erythrocytic cycle. *None of the options* - This option is incorrect because the release of merozoites is directly responsible for the fever spikes in malaria.

Question 1

All of the following helps in the diagnosis of leishmaniasis except:

Accepted Answer

Immobilisation test

Answer

Examination of the bone marrow

Answer

Blood smear

Answer

Aldehyde test

Question 2

Which of the following parasite infections predispose to malignancies? (Select all that apply)

Accepted Answer

Schistosomiasis

Answer

Clonorchiasis

Answer

Guinea worm infection

Answer

Paragonimus westermani

Question 3

18 years old male developed meningitis 5 days after taking a bath in a pond. The likely causative organism -

Accepted Answer

Naegleria fowleri

Answer

Cryptococcus

Answer

Enterococcus

Answer

Meningococcus

Question 4

A pregnant lady had no complaints but mild cervical lymphadenopathy in first trimester. She was prescribed spiramycin but she was noncompliant. Baby was born with hydrocephalus and intracerebral calcification. Which of these is likely cause ?

Accepted Answer

Toxoplasmosis

Answer

CMV

Answer

Rubella

Answer

Herpes

Question 5

All of the following are known to cause biliary obstruction EXCEPT:

Accepted Answer

Ancylostoma

Answer

Fasciola

Answer

Ascariasis

Answer

Clonorchis

Question 6

Brain abscess in immunodeficient person is due to :

Accepted Answer

Toxoplasma gondii

Answer

Aspergillus

Answer

Cryptococcus

Answer

Candida

Question 7

Cyclops play an important role in the transmission of:

Accepted Answer

Dracunculiasis

Answer

Typhoid

Answer

Ancylostomiasis

Answer

Yellow fever

Question 8

Diarrhea syndrome in an AIDS patient can be due to which of the following? a) Rota virus b) Cryptosporidium c) Adenovirus d) E. coli

Accepted Answer

Cryptosporidium

Answer

Adenovirus

Answer

Rota virus

Answer

E. coli

Question 9

In a rural clinic, a 3-year-old girl child is brought by her mother and is emaciated. Her hemoglobin was 5 g/dL. The girl also has edema over her knees and ankles with discrete rash on her knees, ankles and elbows. The most likely worm infestation causing these manifestations is:

Accepted Answer

Hookworm

Answer

Roundworm

Answer

Pinworm

Answer

Whipworm

Question 10

The spike of fever in malaria is at the time of release of ?

Accepted Answer

Merozoites

Answer

Sporozoites

Answer

Hypnozoites

Answer

None of the options

Parasitology — MCQs

Parasitology — MCQs

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