Emerging and Re-emerging Infections Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Emerging and Re-emerging Infections. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Emerging and Re-emerging Infections Indian Medical PG Question 1: All of the following are zoonosis, except:
- A. Japanese Encephalitis
- B. Plague
- C. Tuberculosis
- D. HIV (Correct Answer)
Emerging and Re-emerging Infections Explanation: ***HIV***
- While HIV originated from **simian immunodeficiency virus (SIV)** in non-human primates, it is **no longer considered a zoonosis** because transmission now occurs exclusively **human-to-human**.
- The virus has fully adapted to **human hosts**, and there is **no ongoing animal reservoir** contributing to the current epidemic.
- Zoonotic diseases require **active animal-to-human transmission**, which does not apply to HIV in its current form.
*Japanese Encephalitis*
- This is a **mosquito-borne viral disease** that primarily circulates between **mosquitoes, pigs, and birds**.
- Humans are **accidental dead-end hosts**, making this a true **zoonotic disease**.
*Plague*
- Caused by **Yersinia pestis**, which naturally infects **small mammals (rodents)** and their fleas.
- Humans become infected through **flea bites** or direct contact with infected animals, making it a **classic zoonosis**.
*Tuberculosis*
- While most human TB is caused by **M. tuberculosis** (human-to-human), **M. bovis** causes **zoonotic TB**.
- Transmitted from **infected cattle** to humans via **unpasteurized dairy products** or close contact with infected animals.
- This animal-to-human transmission qualifies TB as a **zoonotic disease**.
Emerging and Re-emerging Infections Indian Medical PG Question 2: Urban malaria is spread by
- A. Anopheles stephensi (Correct Answer)
- B. Culex fatigans
- C. Anopheles gambiae
- D. Anopheles culicifacies
Emerging and Re-emerging Infections Explanation: ***Anopheles stephensi***
- This mosquito species is a predominant vector for **urban malaria**, particularly in India and the Middle East, due to its ability to breed in artificial containers and urban water sources.
- Its presence in urban environments facilitates the transmission of malaria in densely populated areas.
*Culex fatigans*
- This species is better known as **Culex quinquefasciatus** and is a primary vector for **filariasis** (elephantiasis), not malaria.
- It also transmits **West Nile virus** and **Japanese encephalitis**, but is not a significant vector for human malaria.
*Anopheles gambiae*
- This is the primary vector for malaria in **sub-Saharan Africa** due to its highly efficient transmission and opportunistic breeding habits.
- While it causes significant malaria burden globally, its distribution is largely rural and sub-Saharan, not typically urban malaria in the context of the Indian subcontinent.
*Anopheles culicifacies*
- This species is a major vector for **rural malaria in India**, thriving in agricultural areas and fresh water collections.
- It is not typically associated with the spread of malaria in densely populated urban settings, unlike *Anopheles stephensi*.
Emerging and Re-emerging Infections Indian Medical PG Question 3: Match List-I with List-II and select the correct answer using the code given below the Lists:
List-I (Vectors):
A. Hard ticks
B. Sandflies
C. Louse
D. Soft ticks
List-II (Diseases):
1. Oriental sore
2. Epidemic typhus
3. Tularemia
4. Relapsing fever
- A. A→4 B→1 C→3 D→2
- B. A→1 B→2 C→3 D→4
- C. A→2 B→4 C→1 D→3
- D. A→3 B→1 C→2 D→4 (Correct Answer)
Emerging and Re-emerging Infections Explanation: ***A→3 B→1 C→2 D→4***
- **Hard ticks** (A) are primary vectors for **tularemia** (3), transmitting *Francisella tularensis* through their bite during blood feeding.
- **Sandflies** (B) transmit **oriental sore** (1), the cutaneous form of **leishmaniasis** caused by *Leishmania tropica* and other species.
*A→4 B→1 C→3 D→2*
- Incorrectly matches **hard ticks** with **relapsing fever**, which is specifically transmitted by **soft ticks** (*Ornithodoros* species).
- Misassociates **louse** with **tularemia**, when **body lice** are established vectors for **epidemic typhus**.
*A→1 B→2 C→3 D→4*
- Wrongly pairs **hard ticks** with **oriental sore**, which requires **sandfly** vectors for transmission of *Leishmania* parasites.
- Incorrectly matches **sandflies** with **epidemic typhus**, a louse-borne disease caused by *Rickettsia prowazekii*.
*A→2 B→4 C→1 D→3*
- Mismatches **hard ticks** with **epidemic typhus**, which is transmitted by **body lice**, not tick species.
- Incorrectly associates **soft ticks** with **tularemia**, when they are specific vectors for **relapsing fever** caused by *Borrelia* species.
Emerging and Re-emerging Infections Indian Medical PG Question 4: Match the following: A) Caplan syndrome- 1) Found first in coal worker B) Asbestosis- 2) Upper lobe predominance C) Mesothelioma- 3) Involves lower lobe D) Sarcoidosis- 4) Pleural effusion is seen
- A. A-3, B-4, C-2, D-1
- B. A-1, B-4, C-3, D-2 (Correct Answer)
- C. A-4, B-2, C-3, D-1
- D. A-2, B-4, C-3, D-1
Emerging and Re-emerging Infections Explanation: **A-1, B-4, C-3, D-2**
- **Caplan syndrome** was first described in **coal workers** with **rheumatoid arthritis** and progressive massive fibrosis.
- **Asbestosis** is often associated with **pleural effusion**, which can be benign or malignant.
- **Mesothelioma** typically involves the **lower lobes** of the lungs, specifically the pleura, and is strongly linked to asbestos exposure.
- **Sarcoidosis** is characterized by **non-caseating granulomas**, which have a predilection for the **upper lobes** of the lungs.
*A-3, B-4, C-2, D-1*
- This option incorrectly states that Caplan syndrome involves the lower lobe; **Caplan syndrome** is defined by the presence of large nodules in the lungs of coal workers with rheumatoid arthritis, and their specific lobar distribution is not a defining characteristic.
- This option incorrectly states that Mesothelioma has an upper lobe predominance; **Mesothelioma** is a pleural malignancy and typically involves the **lower lobes**, extending along the pleura.
*A-4, B-2, C-3, D-1*
- This option incorrectly associates Caplan syndrome with pleural effusion; **Caplan syndrome** manifests as rheumatoid nodules in the lungs, not primarily pleural effusion.
- This option incorrectly states that Asbestosis has an upper lobe predominance; **Asbestosis** predominantly affects the **lower lobes** of the lungs, causing interstitial fibrosis.
*A-2, B-4, C-3, D-1*
- This option incorrectly states that Caplan syndrome has an upper lobe predominance; the defining feature of **Caplan syndrome** is the combination of rheumatoid arthritis and pneumoconiosis, not specific lobar involvement.
- This option correctly identifies pleural effusion with asbestosis and lower lobe involvement with mesothelioma, but **Caplan syndrome** is not characterized by upper lobe predominance.
Emerging and Re-emerging Infections Indian Medical PG Question 5: Influenza virus causes new epidemic by (3-5 yrs)-
- A. Cycle trends
- B. Antigenic drift (Correct Answer)
- C. Mosaicism
- D. Antigenic shift
Emerging and Re-emerging Infections Explanation: ***Antigenic drift***
- **Antigenic drift** involves minor changes in the **hemagglutinin (HA)** and **neuraminidase (NA)** surface proteins of the influenza virus due to point mutations.
- These minor changes allow the virus to slightly evade the host's immune system, leading to **seasonal epidemics** (typically every 2-3 years) as pre-existing immunity is less effective.
*Cycle trends*
- This term is too general and does not specifically describe the ** virological mechanism** responsible for influenza epidemics.
- While influenza does exhibit cyclical patterns, "cycle trends" doesn't explain the underlying biological process of viral evolution.
*Mosaicism*
- **Mosaicism** refers to the presence of two or more populations of cells with different genotypes within a single individual.
- This genetic phenomenon is completely unrelated to how influenza viruses cause new epidemics.
*Antigenic shift*
- **Antigenic shift** involves abrupt, major changes in the HA or NA proteins, usually through **gene reassortment** when two different influenza viruses co-infect the same cell.
- This leads to entirely **new viral subtypes** that can cause global **pandemics** (less frequently, perhaps every 10-40 years), not the more regular 3-5 year epidemics.
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