Tropical Medicine — MCQs
All of the following helps in the diagnosis of leishmaniasis except:
A person presents to the hospital with fever and chills. Fever profile is ordered and is found to be negative for malaria and dengue. Rk39 test is found to be positive. What is the treatment of choice?
Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?
Which of the following statements regarding dengue fever is false?
A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?
Sheathed microfilariae with two nuclei at the tail tip is suggestive of?
Which of the following drugs has gametocidal action against all species of Plasmodium?
Kala azar is transmitted by:
In which of the following conditions is glucocorticoid used?
All of the following are seen in cerebral malaria, except:
Tropical Medicine Indian Medical PG Practice Questions and MCQs
Question 1: All of the following helps in the diagnosis of leishmaniasis except:
- A. Immobilisation test (Correct Answer)
- B. Examination of the bone marrow
- C. Blood smear
- D. Aldehyde test
Explanation: ***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.
Question 2: A person presents to the hospital with fever and chills. Fever profile is ordered and is found to be negative for malaria and dengue. Rk39 test is found to be positive. What is the treatment of choice?
- A. Amphotericin B (Correct Answer)
- B. Dapsone
- C. Hydroxychloroquine
- D. Griseofulvin
Explanation: Amphotericin B - A positive RK39 test suggests visceral leishmaniasis (kala-azar), especially with fever and chills in an endemic area [1]. - Amphotericin B (specifically liposomal Amphotericin B) is a highly effective and often the drug of choice for treating visceral leishmaniasis, particularly in severe cases or regions with antimonial resistance. Dapsone - Dapsone is primarily used in the treatment of leprosy and بعض forms of dermatitis (e.g., dermatitis herpetiformis). - It has no significant role in treating leishmaniasis. Hydroxychloroquine - Hydroxychloroquine is an antimalarial drug also used for certain autoimmune diseases like lupus and rheumatoid arthritis [2]. - It is ineffective against leishmaniasis. Griseofulvin - Griseofulvin is an antifungal medication used to treat dermatophyte infections (e.g., ringworm of the skin, hair, or nails). - It has no activity against Leishmania parasites.
Question 3: Patient: fever, joint pain, rash. Recent history of mosquito bite. Most likely diagnosis in urban area?
- A. Dengue
- B. Japanese Encephalitis
- C. Malaria
- D. Chikungunya (Correct Answer)
Explanation: ***Chikungunya*** - **Chikungunya** is a viral disease transmitted by mosquitoes that commonly presents with **fever**, severe **joint pain** (polyarthralgia), and a **rash**, fitting the patient's symptoms. - Its high prevalence in **urban areas** and recent history of **mosquito bites** make it a strong diagnostic consideration. *Dengue* - While Dengue also causes **fever** [1] and a **rash**, it is more typically associated with **severe muscle and bone pain** ("breakbone fever"), and **hemorrhagic manifestations** or shock, which are not mentioned. - **Joint pain** in dengue is usually less debilitating than in chikungunya. *Japanese Encephalitis* - This is a serious **neurological infection** characterized by **fever**, **headache**, seizures, and altered mental status, rather than prominent joint pain and rash. - It primarily affects the **brain** and is less likely to present with this specific symptom triad. *Malaria* - Malaria is characterized by **cyclic fevers**, chills, sweating, and fatigue, but typically **does not present with a rash** [1] or significant joint pain. - It is caused by a **parasite** transmitted by *Anopheles* mosquitoes, and its clinical picture differs from the described symptoms.
Question 4: Which of the following statements regarding dengue fever is false?
- A. Common in south Asian region
- B. Transmitted by Aedes aegypti
- C. Thrombocytopenia
- D. Subclinical cases never occur (Correct Answer)
Explanation: **Subclinical cases never occur** - This statement is false because **subclinical** or **asymptomatic infections** are common in dengue fever, meaning many infected individuals do not develop noticeable symptoms but can still transmit the virus. - Studies indicate that the ratio of asymptomatic to symptomatic cases can be as high as 4:1, playing a significant role in **virus transmission** and **herd immunity**. *Common in south Asian region* - This statement is true; **dengue fever** is highly **endemic** in South Asian regions, including countries like India, Bangladesh, and Pakistan, due to suitable climatic conditions for the **Aedes mosquito** and high population density. - The region experiences annual outbreaks, particularly during **monsoon seasons**, leading to a substantial public health burden. *Transmitted by Aedes aegypti* - This statement is true. Dengue fever is primarily transmitted to humans through the bite of infected female **Aedes aegypti mosquitoes**. - **Aedes albopictus** can also act as a vector, but **Aedes aegypti** is considered the main vector in most urban areas. *Thrombocytopenia* - This statement is true. **Thrombocytopenia** (low platelet count) is a hallmark of dengue fever, often correlating with disease severity and risk of **hemorrhage**. - As platelet counts drop, patients are at higher risk of **bleeding complications**, especially in **severe dengue**.
Question 5: A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?
- A. Strongyloides stercoralis (Correct Answer)
- B. Ascaris lumbricoides
- C. Ancylostoma duodenale
- D. Schistosoma mansoni
Explanation: ***Strongyloides stercoralis*** - The presence of **larvae** in the stool [2], particularly **rhabditiform larvae**, is characteristic of *Strongyloides stercoralis* infection, as this parasite has an **autoinfective cycle** involving larval stages in the human host [2]. - In HIV-positive patients, *Strongyloides* can cause **hyperinfection syndrome**, leading to severe gastrointestinal symptoms like foul-smelling stools, and increased larval shedding [2]. *Ascaris lumbricoides* - *Ascaris lumbricoides* is a large intestinal nematode, but it typically presents with **ova** (eggs) in the stool, not larvae, as the eggs hatch in the small intestine. - While it can cause gastrointestinal symptoms, the hallmark microscopic finding in stool samples is the presence of **mammillated or decorticated eggs**. *Ancylostoma duodenale* - *Ancylostoma duodenale* (hookworm) infections are identified by the presence of **eggs** in the stool [1], which are typically oval with a thin shell and contain a developing larva. - Hookworm larvae usually develop in **soil** and infect humans through skin penetration, rather than being commonly found in stool samples from intestinal infection [1]. *Schistosoma mansoni* - *Schistosoma mansoni* is a **blood fluke** that causes intestinal schistosomiasis, characterized by the presence of **spined eggs** in the stool. - The parasite's life cycle involves **freshwater snails** as intermediate hosts, and a **larval stage (cercariae)** that penetrates human skin, but larvae are not typically found in human stool.
Question 6: Sheathed microfilariae with two nuclei at the tail tip is suggestive of?
- A. Onchocerca volvulus
- B. Brugia malayi (Correct Answer)
- C. Wuchereria bancrofti
- D. Loa loa
Explanation: ***Brugia malayi*** - Microfilariae of *Brugia malayi* are characterized by a **sheathed tail** with **two distinct nuclei** at the very tip of the tail. - This morphological feature, along with the presence of multiple discrete nuclei throughout the body, is key for its identification. *Wuchereria bancrofti* - While *Wuchereria bancrofti* also has a **sheathed tail**, its tail is typically **free of nuclei** or has terminal nuclei that are not distinct or paired. - The nuclei of *W. bancrofti* are more scattered and less clearly defined throughout the body compared to *Brugia*. *Onchocerca volvulus* - *Onchocerca volvulus* microfilariae are **unsheathed** and have a **tapered tail without nuclei**. - They are typically found in the skin, not the blood, and lack the characteristic two nuclei at the tail tip. *Loa loa* - *Loa loa* microfilariae are also **sheathed** but have a **tapered tail with nuclei extending to the tip**, not specifically two distinct nuclei at the tail. - Their nuclei are irregularly arranged within the tail, differentiating them from *Brugia malayi*.
Question 7: Which of the following drugs has gametocidal action against all species of Plasmodium?
- A. Primaquine (Correct Answer)
- B. Quinine
- C. Chloroquine
- D. None of the options
Explanation: ***Primaquine*** - **Primaquine** is a **8-aminoquinoline** that is effective against the **gametocytes** of all *Plasmodium* species, including *P. falciparum*. - Its gametocidal action is crucial for **blocking transmission** of malaria, as gametocytes are the parasite forms ingested by mosquitoes. *Quinine* - **Quinine** is a **blood schizonticide** primarily used for treating acute, uncomplicated malaria, especially due to **chloroquine-resistant *P. falciparum***. - While it has some activity against *P. vivax* and *P. malariae* gametocytes, its action against mature *P. falciparum* gametocytes is limited. *Chloroquine* - **Chloroquine** is a highly effective **blood schizonticide** for **sensitive *P. falciparum***, *P. vivax*, *P. ovale*, and *P. malariae*. - It rapidly clears asexual parasites but has no effect on **mature *P. falciparum* gametocytes** and therefore does not prevent transmission of this species. *None of the options* - This option is incorrect because **Primaquine** possesses the described broad-spectrum gametocidal activity.
Question 8: Kala azar is transmitted by:
- A. Tse tse fly
- B. Sandfly (Correct Answer)
- C. Hard tick
- D. Culex mosquito
Explanation: ***Sandfly*** - **Kala azar**, also known as **visceral leishmaniasis**, is a severe parasitic disease caused by **Leishmania donovani**. - This parasite is transmitted to humans through the bite of an infected female **phlebotomine sandfly**. *Tse tse fly* - The **tse tse fly** is the vector for **African trypanosomiasis**, also known as **sleeping sickness**. - It transmits **Trypanosoma brucei**, a different parasitic organism than the one causing kala azar. *Hard tick* - **Hard ticks** are vectors for several diseases, including **Lyme disease** (Borrelia burgdorferi), **Rocky Mountain spotted fever** (Rickettsia rickettsii), and **anaplasmosis**. - They are not associated with the transmission of leishmaniasis. *Culex mosquito* - The **Culex mosquito** is a common vector for diseases such as **West Nile virus**, **Japanese encephalitis**, and **filariasis**. - It does not transmit the **Leishmania parasite** responsible for kala azar.
Question 9: In which of the following conditions is glucocorticoid used?
- A. Severe typhoid (Correct Answer)
- B. E. coli septicemia
- C. Cerebral malaria
- D. Leishmaniasis
Explanation: ***Severe typhoid*** * **Glucocorticoids** (e.g., **dexamethasone**) are indicated in **severe typhoid fever** with altered mental status, delirium, stupor, coma, or shock, as they can reduce inflammation and improve neurological outcomes. * Their use in severe typhoid can decrease mortality by attenuating the systemic inflammatory response induced by *Salmonella Typhi*. *E. coli septicemia* * The use of **glucocorticoids** in **bacterial sepsis**, including *E. coli* septicemia, is generally controversial and not recommended unless there is confirmed or suspected **adrenal insufficiency**. * Routine use can increase the risk of secondary infections and other adverse effects without clear mortality benefit in immunocompetent patients. *Cerebral malaria* * **Glucocorticoids** are **contraindicated** in **cerebral malaria** because studies have shown they increase the risk of complications (e.g., gastrointestinal bleeding, seizures, hyperglycemia, infections) without improving neurological outcomes or survival. * Their use can worsen immune suppression in a disease already characterized by significant immune dysregulation. *Leishmaniasis* * **Glucocorticoids** are **not a primary treatment** for **leishmaniasis**, which is caused by a protozoan parasite and requires specific antileishmanial drugs. * While they might be used to manage severe inflammatory reactions in specific forms (e.g., post-kala-azar dermal leishmaniasis), they are not a standard therapeutic intervention and can even exacerbate the infection by suppressing the immune response.
Question 10: All of the following are seen in cerebral malaria, except:
- A. Acute respiratory distress syndrome
- B. Heavy parasitemia
- C. Hyperglycaemia (Correct Answer)
- D. Thrombocytopaenia
Explanation: All of the following are seen in cerebral malaria, except: ***Hyperglycaemia*** - **Hypoglycemia**, not hyperglycemia, is a common complication of cerebral malaria, especially in children and pregnant women, due to increased glucose consumption by red blood cells with high parasitic load and quinine treatment. - While extremely rare, **hyperglycemia** is an atypical finding in severe malaria and would warrant investigation for co-existing conditions, as it is not directly caused by the disease pathophysiology. *Thrombocytopaenia* - **Thrombocytopaenia** is a very common hematologic abnormality in both uncomplicated and severe malaria, including cerebral malaria. - It is thought to occur due to increased platelet destruction, splenic sequestration, and bone marrow suppression. *Acute respiratory distress syndrome* - **Acute respiratory distress syndrome (ARDS)** is a severe pulmonary complication that can occur in cerebral malaria, particularly in adults. - It is often associated with fluid overload, inflammation, and pulmonary edema. *Heavy parasitemia* - **Heavy parasitemia** (high parasitic load) is a hallmark of severe malaria, including cerebral malaria [1]. - It involves a significant percentage of red blood cells being infected, leading to widespread microvascular obstruction and organ dysfunction [1].
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