Parasitology Practice Questions

Q: Tropical pulmonary eosinophilia is most characteristically seen due to which of the following infections?

Filaria. *Filaria* - **Tropical pulmonary eosinophilia (TPE)** is a hypersensitivity reaction to microfilariae from filarial nematodes like *Wuchereria bancrofti* and *Brugia malayi* [1]. - It is characterized by cough, dyspnea, wheezing, and marked **peripheral eosinophilia**, with interstitial infiltrates on chest X-ray [1]. *Roundworm* - **Ascaris lumbricoides** can cause **Loeffler's syndrome**, a transient pulmonary infiltration with eosinophilia during larval migration, but not chronic TPE [2]. - Symptoms are usually less severe and self-limiting compared to TPE [2]. *Trichinella* - **Trichinella spiralis** causes **trichinellosis**, presenting with muscle pain, fever, and periorbital edema, possibly with eosinophilia, but typically does not manifest as TPE. - Pulmonary involvement is rare and not the characteristic feature. *Ancylostoma* - **Hookworm (Ancylostoma duodenale, Necator americanus)** larvae can cause mild pulmonary symptoms and eosinophilia during migration through the lungs [3]. - However, they also do not typically lead to the severe and chronic pulmonary symptoms seen in TPE [3].

Q: Babesiosis is most commonly transmitted by:

Ticks. **_Ticks_** - Babesiosis is a **tick-borne illness** caused by *Babesia* parasites, primarily *Babesia microti* in North America. - The main vector is the **deer tick** (*Ixodes scapularis*), which also transmits **Lyme disease**. *Rats* - Rats are known reservoirs for various diseases (e.g., **hantavirus**, **leptospirosis**), but they are not the primary vectors for babesiosis. - While *Babesia microti* can infect rodents, **direct transmission** to humans from rats is not the most common route. *Sand fly* - Sand flies are vectors for diseases like **leishmaniasis** and **Bartonellosis**. - They are not associated with the transmission of *Babesia* parasites. *Pigs* - Pigs can be reservoirs for certain zoonotic diseases (e.g., **cysticercosis**, **trichinellosis**). - They do not typically serve as vectors for babesiosis transmission to humans.

Q: Montenegro test is used for diagnosis of:

Kala azar. ***Kala azar*** - The Montenegro test, also known as the **leishmanin skin test (LST)**, detects delayed-type hypersensitivity to **Leishmania antigens**, indicating past or present infection with *Leishmania donovani*, the causative agent of **kala azar (visceral leishmaniasis)** [1]. - A **positive reaction** (induration of 5 mm or more) signifies cell-mediated immunity against the parasite [1]. *Leptospirosis* - Diagnosed primarily through **serological tests** like the **Microscopic Agglutination Test (MAT)** or by detecting the organism through **culture** or **PCR**. - The Montenegro test is not used for the diagnosis of **leptospirosis**. *Malaria* - Diagnosed by identifying **parasites in blood smears** (thick and thin films) or by **antigen detection rapid diagnostic tests (RDTs)**. - The Montenegro test plays no role in the diagnosis of **malaria**. *Leprosy* - Diagnosed through **clinical signs and symptoms**, microscopic examination of **skin or nerve biopsies for acid-fast bacilli**, or sometimes the **lepromin skin test**. - While the lepromin test is a skin test, it targets *Mycobacterium leprae* antigens and is distinct from the Montenegro test for leishmaniasis.

Q: The following parasitic infections predispose to malignancies: A) Paragonimus westermani B) Guinea worm infection C) Clonorchiasis D) Schistosomiasis

C and D. ***C and D*** - **Clonorchiasis**, caused by *Clonorchis sinensis*, is strongly linked to **cholangiocarcinoma**, cancer of the bile ducts. - **Schistosomiasis**, particularly infection with *Schistosoma haematobium*, is a significant risk factor for **bladder cancer** [1]. *A and B* - **Paragonimus westermani** (lung fluke) can cause chronic inflammation and fibrosis in the lungs but is not directly associated with malignancy. - **Guinea worm infection** (*Dracunculus medinensis*) causes painful ulcers but does not predispose to cancer. *B and D* - **Guinea worm infection** does not cause cancer. - While **Schistosomiasis** does predispose to malignancy [1], the pairing with Guinea worm makes this option incorrect overall. *A and C* - **Paragonimus westermani** is not known to cause malignancy. - **Clonorchiasis** is linked to malignancy, but its pairing with an incorrect option makes this choice wrong.

Q: Which disease is transmitted by all components of blood?

Malaria. ***Malaria*** - **Malaria** is caused by *Plasmodium* parasites and is uniquely transmissible through **all blood components** including whole blood, packed RBCs, platelets, fresh frozen plasma, and cryoprecipitate - The parasites exist within **red blood cells** during the blood stage and can also be present as **free merozoites** in plasma during rupture of RBCs - **Critical for blood bank safety**: Even small volumes of any blood component from an infected donor can transmit malaria - Blood donations require extensive screening for malaria in endemic areas and from donors with travel history *Hepatitis B* - **Hepatitis B virus (HBV)** is highly transmissible through blood and present in plasma, but modern blood banking practice includes **universal HBsAg screening** which has virtually eliminated transmission - While technically present in multiple components, the question emphasizes diseases where **all components** pose equal transmission risk without modern screening *Syphilis* - **Syphilis** caused by *Treponema pallidum* can be transmitted via blood transfusion, but the organism is **fragile** and does not survive beyond 72-96 hours in refrigerated blood - Transmission risk is significantly reduced by standard blood storage conditions and routine serological screening - Not efficiently transmitted through all stored blood components *Toxoplasma* - **Toxoplasma gondii** transmission occurs primarily through **leukocyte-containing products** (whole blood, platelet concentrates) - Transmission via **cell-free plasma** or washed RBCs is uncommon - Does not have the same broad transmission profile across all blood components as malaria

Q: All of the following diseases may be acquired by ingestion except -

Leishmaniasis. ***Leishmaniasis*** - Leishmaniasis is typically acquired through the bite of an infected **sandfly vector**, not by ingestion. - The parasite lives and multiplies in the sandfly's midgut and is transmitted to humans during a blood meal. *Taeniasis* - **Taeniasis** is acquired by ingesting undercooked meat containing **Taenia larvae** (cysticerci). - Humans can get infected by eating raw or undercooked beef (for *Taenia saginata*) or pork (for *Taenia solium*). *Guinea worm* - **Guinea worm disease** (*Dracunculus medinensis*) is acquired by ingesting water contaminated with water fleas (copepods) that harbor the infective larvae. - The larvae mature in the human host after ingestion of the infected water. *Toxoplasmosis* - **Toxoplasmosis** can be acquired by ingesting undercooked meat containing **Toxoplasma cysts** or by consuming food/water contaminated with cat feces (containing oocysts). - It can also be transmitted congenitally from mother to fetus.

Q: A 65-year old man presented with skin lesions on his chest and left arm and shoulder six weeks after returning from a vacation in Belize at the beach in the rain forest. The lesions occasionally stung, drained a dark exudates, and enlarged despite two weeks of treatment with cephalexin. The patient had no constitutional symptoms. Physical examination revealed five nodules of varying sizes with surrounding erythema and a central pore through which a single, moving larva was observed. The larvae coming out of the pores are-

Dermatobia hominis. ***Dermatobia hominis*** - The description of **cutaneous nodules** with a central pore from which a **moving larva** is observed, particularly after travel to a tropical region like Belize, is classic for **furuncular myiasis** caused by **Dermatobia hominis** larvae (human botfly). - The **"occasional stinging"** and **"dark exudate"** are characteristic symptoms of the larva burrowing in the skin and secreting waste products. *Loa loa* - **Loa loa** (African eye worm) is a filarial nematode that migrates through **subcutaneous tissues** and occasionally across the eye, causing **Calabar swellings**. - It does not present as a **furuncular lesion** with a visible central moving larva emerging from a pore. *Diphyllobothrium latum* - **Diphyllobothrium latum** is a **tapeworm** that infects the intestines and is acquired by consuming undercooked infected fish. - It causes gastrointestinal symptoms and can lead to **vitamin B12 deficiency**, but it does not produce **skin lesions with moving larvae**. *Dracunculus medinensis* - **Dracunculus medinensis** (guinea worm) infection typically results in a **painful blister** on the lower limbs, from which the female worm emerges to release larvae when exposed to water. - While it involves a skin lesion, the presentation of **multiple nodules with a central pore revealing a moving larva** is not consistent with **dracunculiasis**.

Q: Casoni's test is used in the diagnosis of which of the following infections?

Echinococcus granulosus. ***Echinococcus granulosus*** - The **Casoni's test** is an intradermal skin test historically used to detect antigens of **Echinococcus granulosus**, the causative agent of **hydatid disease**. - A **positive reaction** indicates previous exposure to Echinococcus antigens, leading to a local hypersensitivity reaction. *Toxocariasis* - Diagnosis of **toxocariasis** (visceral larva migrans) primarily relies on **serological tests** like ELISA to detect antibodies against *Toxocara* antigens. - While Casoni's test involves an immune reaction, it is not specific or used for **Toxocara** detection. *Toxoplasmosis* - **Toxoplasmosis** is diagnosed through **serological tests** measuring IgG and IgM antibodies to *Toxoplasma gondii*, or by PCR for detecting parasitic DNA. - The Casoni's test has no role in the diagnosis of **Toxoplasma** infection. *Syphilis* - Diagnosis of **syphilis** involves **nontreponemal tests** (e.g., VDRL, RPR) for screening and **treponemal tests** (e.g., TPPA, FTA-ABS) for confirmation. - The Casoni's test is entirely unrelated to the diagnostic methods for **syphilis**.

Q: Which micro–organism is responsible for classical presentation of hydrocephalus, chorioretinitis, intracerebral calcification ?

Toxoplasmosis. ***Toxoplasmosis*** - This classic triad of **hydrocephalus**, **chorioretinitis**, and **intracerebral calcifications** is highly indicative of congenital toxoplasmosis. - *Toxoplasma gondii* is an intracellular parasite acquired transplacentally, leading to these severe neurological and ocular manifestations in the fetus. *CMV* - While congenital CMV can cause **intracerebral calcifications** (often periventricular), it typically presents with **microcephaly** rather than hydrocephalus. - CMV is also commonly associated with **sensorineural hearing loss** and hepatosplenomegaly. *Measles* - Congenital measles is extremely rare and can lead to **miscarriage** or **premature birth**, but not the classic triad described. - Measles is known for causing **subacute sclerosing panencephalitis (SSPE)** much later in life, an entirely different clinical picture. *Rubella* - Congenital rubella syndrome (CRS) is characterized by a different constellation of symptoms, including a **PDA (patent ductus arteriosus)**, **cataracts**, and **sensorineural hearing loss**. - While it can cause some central nervous system abnormalities, it does not typically present with hydrocephalus or chorioretinitis with intracerebral calcifications.

Question 1

Tropical pulmonary eosinophilia is most characteristically seen due to which of the following infections?

Accepted Answer

Filaria

Answer

Roundworm

Answer

Trichinella

Answer

Ancylostoma

Question 2

Babesiosis is most commonly transmitted by:

Accepted Answer

Ticks

Answer

Rats

Answer

Sand fly

Answer

Pigs

Question 3

Montenegro test is used for diagnosis of:

Accepted Answer

Kala azar

Answer

Leptospirosis

Answer

Malaria

Answer

Leprosy

Question 4

Which of the following statements regarding diagnosis of malaria are true?

Accepted Answer

Jaswant Singh Bhattacharya (JSB) Stain is used.

Answer

Thin blood film is used to determine parasite concentration.

Answer

As the sensitivity of microscopy is low, it is useful to detect parasite load at high concentrations only.

Answer

Thick blood film is used to detect plasmodium species causing infection.

Question 5

The following parasitic infections predispose to malignancies: A) Paragonimus westermani B) Guinea worm infection C) Clonorchiasis D) Schistosomiasis

Accepted Answer

C and D

Answer

A and B

Answer

B and D

Answer

A and C

Question 6

Which disease is transmitted by all components of blood?

Accepted Answer

Malaria

Answer

Syphilis

Answer

Toxoplasma

Answer

Hepatitis B

Question 7

All of the following diseases may be acquired by ingestion except -

Accepted Answer

Leishmaniasis

Answer

Taeniasis

Answer

Guinea worm

Answer

Toxoplasmosis

Question 8

A 65-year old man presented with skin lesions on his chest and left arm and shoulder six weeks after returning from a vacation in Belize at the beach in the rain forest. The lesions occasionally stung, drained a dark exudates, and enlarged despite two weeks of treatment with cephalexin. The patient had no constitutional symptoms. Physical examination revealed five nodules of varying sizes with surrounding erythema and a central pore through which a single, moving larva was observed. The larvae coming out of the pores are-

Accepted Answer

Dermatobia hominis

Answer

Loa loa

Answer

Diphyllobothrium latum

Answer

Dracunculus medinensis

Question 9

Casoni's test is used in the diagnosis of which of the following infections?

Accepted Answer

Echinococcus granulosus

Answer

Toxocariasis

Answer

Toxoplasmosis

Answer

Syphilis

Question 10

Which micro–organism is responsible for classical presentation of hydrocephalus, chorioretinitis, intracerebral calcification ?

Accepted Answer

Toxoplasmosis

Answer

CMV

Answer

Measles

Answer

Rubella

Parasitology — MCQs

Parasitology — MCQs

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