Vector-Borne Diseases Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Vector-Borne Diseases. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Vector-Borne Diseases Indian Medical PG Question 1: Vector for Zika virus disease is:
- A. Culex
- B. Aedes Aegypti (Correct Answer)
- C. Phlebotomus
- D. Anopheles stephensi
Vector-Borne Diseases Explanation: ***Aedes aegypti***
- The **Aedes aegypti mosquito** is the primary vector responsible for transmitting the Zika virus to humans.
- This mosquito species is also known to transmit other arboviruses, including **dengue** and **chikungunya** viruses.
*Culex*
- **Culex mosquitoes** are known vectors for diseases such as **West Nile virus** and **Japanese encephalitis**.
- They are generally not considered primary vectors for the Zika virus.
*Phlebotomus*
- **Phlebotomus (sandflies)** are vectors for parasitic diseases, most notably **leishmaniasis**.
- They are not involved in the transmission of viral infections like Zika.
*Anopheles stephensi*
- **Anopheles mosquitoes**, particularly *Anopheles stephensi*, are the main vectors for **malaria**.
- They do not play a role in the transmission of the Zika virus.
Vector-Borne Diseases Indian Medical PG Question 2: Which of the following diseases has the largest submerged portion in the iceberg model of disease?
- A. Influenza (Correct Answer)
- B. Chickenpox
- C. Tetanus
- D. Rabies
Vector-Borne Diseases Explanation: **The Iceberg Model of Disease** represents the concept that for many diseases, only a small portion of cases (the "tip" above water) are clinically apparent and reported, while a much larger portion (the "submerged" part) consists of asymptomatic, subclinical, or undiagnosed cases.
***Influenza***
- Has the **largest submerged portion** among the given options, with **50-75% of infections being asymptomatic or mild** and going undiagnosed
- High transmissibility and varied clinical presentation contribute to significant hidden burden
- Only severe cases requiring hospitalization typically get reported, representing just the "tip of the iceberg"
- Classic example of diseases with large subclinical-to-clinical ratio
*Chickenpox*
- Most cases are **clinically apparent** with characteristic vesicular rash
- Asymptomatic infections are rare due to distinctive clinical features
- High visibility of cases reduces the submerged portion significantly
*Tetanus*
- **Severe, acute neurological condition** with distinct clinical manifestations (trismus, risus sardonicus, opisthotonus)
- Almost all cases are diagnosed due to dramatic presentation
- Virtually no submerged portion - what exists clinically is recognized
*Rabies*
- **Nearly uniformly fatal** once symptoms appear, making all symptomatic cases clinically evident
- No asymptomatic or mild phase after symptom onset
- Minimal to no submerged portion in the iceberg model
Vector-Borne Diseases Indian Medical PG Question 3: Which of the following diseases is transmitted by Mansonia?
- A. Chikungunya
- B. Bancroftian filariasis (Correct Answer)
- C. Japanese encephalitis
- D. Dengue
Vector-Borne Diseases Explanation: ***Bancroftian filariasis***
- **Bancroftian filariasis** (caused by *Wuchereria bancrofti*) is commonly transmitted by three mosquito genera: *Culex*, *Anopheles*, and *Mansonia*.
- *Mansonia* mosquitoes are known vectors for the larvae of *Wuchereria bancrofti*, which mature into adult worms in the human lymphatic system.
*Chikungunya*
- Chikungunya virus is primarily transmitted by mosquitoes of the genus *Aedes*, particularly **_Aedes aegypti_** and **_Aedes albopictus_**.
- *Mansonia* mosquitoes are not considered primary or significant vectors for the transmission of Chikungunya.
*Japanese encephalitis*
- Japanese encephalitis virus is mainly transmitted by mosquitoes of the genus _Culex_, specifically **_Culex tritaeniorhynchus_**.
- While *Mansonia* mosquitoes may occasionally carry the virus, they are not primary vectors for its transmission to humans.
*Dengue*
- Dengue virus is primarily transmitted by **_Aedes aegypti_** and **_Aedes albopictus_** mosquitoes.
- *Mansonia* mosquitoes are not implicated in the transmission cycle of Dengue fever.
Vector-Borne Diseases Indian Medical PG Question 4: A patient hailing from Delhi presents with fever, arthralgia, and extensive petechial rash for 3 days. Lab investigations revealed a hemoglobin of 9 g/ dL, a white blood cell count of 9000 cells/mm3, a platelet count of 20000 cells/mm3, and a prolonged bleeding time. The clotting time was normal. What is the most likely diagnosis?
- A. Dengue (Correct Answer)
- B. Malaria
- C. Scrub typhus
- D. Typhoid
Vector-Borne Diseases Explanation: Dengue
- The combination of **fever, arthralgia, extensive petechial rash**, and severe **thrombocytopenia** (platelet count 20,000/mm³) with **prolonged bleeding time** is highly characteristic of severe dengue infection, especially in an endemic area like Delhi [1].
- While leukocytosis (WBC 9000/mm³) is not typical for dengue (usually causes leukopenia), the other features strongly point to dengue hemorrhagic fever [1].
*Malaria*
- Typically presents with **intermittent high fever**, chills, and sweats. While it can cause some thrombocytopenia and anemia, the **extensive petechial rash** is not a characteristic feature.
- **Thrombocytopenia** in malaria is usually milder than observed here, and prolonged bleeding time is less common [2].
*Scrub typhus*
- Caused by Orientia tsutsugamushi, it is characterized by **fever, headache, myalgia, and a characteristic eschar** (necrotic ulcer) at the bite site, which is not mentioned.
- While it can cause rash and some thrombocytopenia, the **petechial rash** and such severe thrombocytopenia with prolonged bleeding time are less typical.
*Typhoid*
- Presents with **sustained high fever**, headache, bradycardia, and sometimes a **rose spot rash** (maculopapular), which is different from a petechial rash.
- Typhoid typically causes **leukopenia** and can lead to gastrointestinal complications like intestinal bleeding, but severe thrombocytopenia and extensive petechiae are not common presenting features.
Vector-Borne Diseases Indian Medical PG Question 5: Which of the following diseases is transmitted by Aedes aegypti?
- A. Japanese encephalitis
- B. Filariasis
- C. Malaria
- D. Yellow fever (Correct Answer)
Vector-Borne Diseases Explanation: ***Yellow fever***
- **Yellow fever** is a viral hemorrhagic disease transmitted primarily by the **Aedes aegypti** mosquito.
- This mosquito species is also responsible for transmitting other arboviruses like **Dengue**, **Chikungunya**, and **Zika** viruses.
*Japanese encephalitis*
- **Japanese encephalitis** is typically transmitted by mosquitoes of the **Culex** genus, particularly **Culex tritaeniorhynchus**.
- It is a leading cause of viral encephalitis in Asia, affecting the brain and central nervous system.
*Filariasis*
- **Lymphatic filariasis** is transmitted by several mosquito genera, including **Culex**, **Anopheles**, and **Aedes**, but it's not exclusively carried by **Aedes aegypti**.
- It is caused by parasitic worms and can lead to severe swelling (lymphedema) and elephantiasis.
*Malaria*
- **Malaria** is transmitted exclusively by infected female **Anopheles mosquitoes**.
- The parasite Plasmodium causes malaria, and different species infect humans, leading to cyclical fevers and chills.
Vector-Borne Diseases Indian Medical PG Question 6: 26-year-old man from Bihar presents with erythematous papules on the face and back of the neck, which are hypopigmented and normoaesthetic, with no nerve thickening. A history of prolonged fever in childhood is present. What is the diagnosis?
- A. Tuberculoid leprosy
- B. Lepromatous leprosy
- C. Lupus vulgaris
- D. Dermal leishmaniasis (PKDL) (Correct Answer)
Vector-Borne Diseases Explanation: ***Dermal leishmaniasis (PKDL)***
- PKDL presents with **erythematous papules** on the face and neck, which are **hypopigmented and normoaesthetic** (intact sensation), fitting the patient's description perfectly.
- A history of **prolonged fever in childhood** in Bihar is highly suggestive of prior **visceral leishmaniasis (kala-azar)**, after which PKDL typically develops (months to years post-treatment).
- The **absence of nerve thickening** and **normal sensation** are key features distinguishing PKDL from leprosy.
- Bihar is an **endemic area** for visceral leishmaniasis in India.
*Tuberculoid leprosy*
- Characterized by **hypopigmented, anaesthetic patches** with **thickened nerves** - both features are absent in this case.
- The **normoaesthetic** nature of lesions here rules out tuberculoid leprosy.
- Lesions are typically **well-demarcated** and few in number.
*Lepromatous leprosy*
- Involves widespread, symmetrical lesions that are often **erythematous nodules** or **diffuse infiltrations**, with multiple nerve involvements.
- Would show **nerve thickening** and eventual sensory loss, which are not present here.
- The clinical picture does not match lepromatous leprosy.
*Lupus vulgaris*
- A form of **cutaneous tuberculosis** presenting as red-brown plaques with an **"apple-jelly" appearance** on diascopy.
- While it can occur on the face, there is no history of fever or connection to visceral leishmaniasis.
- The morphology (papules vs plaques) and epidemiological context favor PKDL.
Vector-Borne Diseases Indian Medical PG Question 7: Which of the following diseases is spread by mosquitoes?
- A. Dengue (Correct Answer)
- B. Listeriosis
- C. Kala azar
- D. Trypanosomiasis
Vector-Borne Diseases Explanation: ***Dengue*** is the correct answer.
- **Dengue fever** is a **mosquito-borne** viral disease transmitted primarily by **Aedes aegypti** and **Aedes albopictus** mosquitoes.
- Symptoms range from mild flu-like illness to severe dengue hemorrhagic fever or dengue shock syndrome.
*Listeriosis*
- Caused by **Listeria monocytogenes**, transmitted through contaminated food consumption.
- **Not spread by mosquitoes** but through foodborne routes or contact with infected animals.
*Kala azar*
- Visceral leishmaniasis caused by **Leishmania parasites**, transmitted by infected **sandflies**, not mosquitoes.
- Affects internal organs including spleen, liver, and bone marrow.
*Trypanosomiasis*
- Includes **African sleeping sickness** (transmitted by **tsetse flies**) and **Chagas disease** (transmitted by **reduviid bugs/kissing bugs**).
- Neither vector is a mosquito.
Vector-Borne Diseases Indian Medical PG Question 8: All are true regarding Japanese encephalitis disease except:
- A. Man acts as reservoir (Correct Answer)
- B. Pig vaccination control transmission
- C. Vector is Culex vishnui
- D. None of the options are true
Vector-Borne Diseases Explanation: ***Man acts as reservoir***
- Humans are considered **dead-end hosts** for Japanese encephalitis; they do not develop sufficiently high viremia to transmit the virus back to mosquitoes.
- The primary reservoirs for the Japanese encephalitis virus are **pigs** and **wading birds**.
*Pig vaccination control transmission*
- **Vaccinating pigs** is an effective strategy to control Japanese encephalitis transmission because pigs are significant amplifier hosts, producing high levels of viremia.
- By reducing the viral load in the pig population, pig vaccination helps **break the transmission cycle** between mosquitoes and humans.
*Vector is Culex vishnui*
- The primary vector involved in the transmission of Japanese encephalitis is indeed **Culex mosquitoes**, with **Culex vishnui complex** being a significant group responsible for its spread in many endemic regions.
- These mosquitoes primarily breed in **rice paddies** and other stagnant water sources, which are common in areas where the disease is prevalent.
*None of the options are true*
- This option is incorrect because the statements regarding **pig vaccination** and the **Culex vishnui** vector are true in the context of Japanese encephalitis.
- The initial premise that "Man acts as reservoir" is the false statement, making it the correct answer to the "except" question.
Vector-Borne Diseases Indian Medical PG Question 9: Kala azar is transmitted by:
- A. Tse tse fly
- B. Sandfly (Correct Answer)
- C. Hard tick
- D. Culex mosquito
Vector-Borne Diseases 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.
Vector-Borne Diseases Indian Medical PG Question 10: All following are at-risk group adults meriting Hepatitis B vaccination in low endemic areas except for which of the following?
- A. Medical/nursing personnel
- B. Patients with chronic liver disease
- C. Diabetics on insulin (Correct Answer)
- D. Patients on chronic hemodialysis
Vector-Borne Diseases Explanation: ***Diabetics on insulin***
- This is the correct answer as the exception based on **guidelines at the time of this exam (2012)**.
- At that time, diabetics were **not routinely listed** as a standard at-risk group for hepatitis B vaccination in low endemic areas, though the ACIP was beginning to recognize increased risk in this population.
- **Current Update (Post-2012):** The **CDC/ACIP now recommends** hepatitis B vaccination for all previously unvaccinated adults with diabetes aged 19-59 years, due to documented increased risk of HBV infection associated with:
- Shared blood glucose monitoring devices
- Assisted blood glucose monitoring in healthcare settings
- Outbreak investigations showing higher transmission rates
- For the purpose of this historical exam question, diabetics were the exception among the listed groups.
*Medical/nursing personnel*
- Healthcare workers are at **high occupational risk** due to frequent exposure to blood and body fluids.
- This has been a **standard, long-standing recommendation** for HBV vaccination regardless of endemic status.
- The risk remains present even in low endemic areas due to potential exposure to infected patients.
*Patients with chronic liver disease*
- Individuals with pre-existing chronic liver disease are at risk of **severe outcomes** if they acquire hepatitis B infection.
- Superimposed acute HBV infection can lead to:
- Rapid progression to cirrhosis
- Acute-on-chronic liver failure
- Hepatocellular carcinoma
- Vaccination is **crucial for prevention** and has been a standard recommendation.
*Patients on chronic hemodialysis*
- Hemodialysis patients face **elevated risk** of HBV acquisition due to:
- Frequent vascular access procedures
- Prolonged time in healthcare settings
- Potential for nosocomial transmission in dialysis units
- Their **immunocompromised state** increases risk of chronic infection and complications.
- Vaccination is a **standard preventive measure** in this population.
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