Air-Borne Diseases Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Air-Borne Diseases. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Air-Borne Diseases Indian Medical PG Question 1: Which of the following infectious diseases has the highest proportion of asymptomatic chronic carriers?
- A. Measles
- B. Rabies
- C. Diphtheria
- D. Hepatitis B (Correct Answer)
Air-Borne Diseases Explanation: ***Hepatitis B***
- **Hepatitis B** infection has a significant proportion of **chronic asymptomatic carriers**, particularly when infection occurs perinatally or in early childhood.
- In adults, approximately **5% develop chronic infection** after acute exposure, and many of these chronic carriers remain asymptomatic while maintaining infectivity.
- Chronic carriers can harbor the virus for years or decades without clinical symptoms, making them an important reservoir for transmission.
- This is a major public health concern as asymptomatic carriers can unknowingly transmit the virus.
*Measles*
- **Measles** is highly contagious and typically presents with **symptomatic disease** in nearly all infected individuals.
- Clinical features include characteristic maculopapular rash, cough, coryza, conjunctivitis, and Koplik's spots.
- Asymptomatic infection is **extremely rare** with measles virus.
*Diphtheria*
- While **asymptomatic pharyngeal carriage** of *Corynebacterium diphtheriae* can occur, it is not the predominant pattern.
- Clinical diphtheria typically presents with pseudomembrane formation, sore throat, and potential systemic toxin effects.
- Carrier rates vary but are not as epidemiologically significant as with Hepatitis B.
*Rabies*
- **Rabies** is almost **100% symptomatic** once the virus reaches the central nervous system.
- There is **no chronic asymptomatic carrier state** in humans.
- Once clinical symptoms appear (encephalitis, hydrophobia, paralysis), the disease is virtually always fatal.
Air-Borne Diseases Indian Medical PG Question 2: Koplik's spots occur in which phase of measles -
- A. Post exanthematous phase
- B. End of prodromal phase (Correct Answer)
- C. Recrudescence phase
- D. Exanthematous phase
Air-Borne Diseases Explanation: ***End of prodromal phase***
- **Koplik's spots**, pathognomonic for measles, typically appear 1-2 days before the onset of the **maculopapular rash**, marking the very end of the **prodromal phase**.
- These are small, white spots with a bluish-white center on an erythematous base, found on the **buccal mucosa** opposite the molars.
*Post exanthematous phase*
- This phase occurs *after* the rash has faded and is characterized by **desquamation** and **cough**, not the appearance of Koplik's spots.
- Koplik's spots would have long disappeared by this stage.
*Recrudescence phase*
- This term usually refers to the **reappearance of symptoms** after a period of improvement, which is not characteristic of Koplik's spots in measles.
- Koplik's spots represent an initial diagnostic sign rather than a recurrent symptom.
*Exanthematous phase*
- The **exanthematous phase** is when the characteristic **maculopapular rash** appears and spreads, typically starting a few days *after* Koplik's spots have already emerged and are beginning to fade.
- While overlap can occur, Koplik's spots are *most prominent* and diagnostic *before* the rash fully develops.
Air-Borne Diseases Indian Medical PG Question 3: Which of the following statements is true regarding the epidemiology of influenza?
- A. Pandemics cannot occur with influenza viruses.
- B. Incubation period is typically 7-10 days.
- C. Humans are the only reservoir for influenza.
- D. Asymptomatic cases can occur and may contribute to transmission. (Correct Answer)
Air-Borne Diseases Explanation: ***Asymptomatic cases can occur and may contribute to transmission.***
- Asymptomatic or mildly symptomatic individuals can shed the virus, contributing to the silent spread of influenza within a community.
- This characteristic makes **influenza control** challenging, as not all infected individuals seek medical attention or are easily identified.
*Incubation period is typically 7-10 days.*
- The typical incubation period for influenza is much shorter, usually **1 to 4 days**, with an average of 2 days.
- A 7-10 day incubation period is more characteristic of infections like **measles** or **mumps**, not influenza.
*Pandemics cannot occur with influenza viruses.*
- Influenza viruses are well-known for their potential to cause **pandemics** through antigenic shifts, leading to novel strains against which the population has little to no immunity.
- Historically, there have been several major influenza pandemics, such as the **1918 Spanish Flu** and the 2009 H1N1 pandemic.
*Humans are the only reservoir for influenza.*
- While humans are a significant reservoir, influenza viruses also circulate in **animal reservoirs** such as birds (especially wild aquatic birds) and pigs.
- These animal reservoirs can serve as sources for new human strains through **inter-species transmission** and genetic reassortment.
Air-Borne Diseases Indian Medical PG Question 4: Which TB drug causes optic neuritis as a side effect?
- A. Isoniazid
- B. Pyrazinamide
- C. Rifampicin
- D. Ethambutol (Correct Answer)
Air-Borne Diseases Explanation: ***Ethambutol***
- **Ethambutol** is known to cause **optic neuritis**, leading to **decreased visual acuity** and impaired **red-green color discrimination**.
- This side effect is **dose-dependent** and usually **reversible** upon discontinuing the drug, though permanent damage can occur with prolonged use.
*Isoniazid*
- **Isoniazid** is primarily associated with **peripheral neuropathy** and **hepatotoxicity**, which can be mitigated with **pyridoxine (vitamin B6)** supplementation.
- While visual disturbances can occur, **optic neuritis** is not its most characteristic or frequent ocular side effect.
*Pyrazinamide*
- The main side effects of **pyrazinamide** include **hepatotoxicity** and **hyperuricemia**, which can lead to **gouty arthritis**.
- It does not typically cause **optic neuritis** or other significant ocular complications.
*Rifampicin*
- **Rifampicin** is well-known for causing **hepatotoxicity**, **red-orange discoloration of body fluids** (urine, tears, sweat), and various **drug interactions** due to enzyme induction.
- Ocular side effects like **optic neuritis** are not a common or characteristic adverse effect of rifampicin.
Air-Borne Diseases Indian Medical PG Question 5: All of the following statements regarding measles are true, except:
- A. Koplik spot are seen on retina (Correct Answer)
- B. I-P is 10-14 days
- C. Long term complication may be seen in form of SSPE
- D. Caused by RNA virus
- E. Rash appears first on face
Air-Borne Diseases Explanation: ***Koplik spot are seen on retina***
- **Koplik spots** are pathognomonic for measles and are typically found on the **buccal mucosa** (inside the cheeks), not on the retina [1].
- These are small, white, or bluish-white lesions with a red halo, appearing before the characteristic rash.
*I-P is 10-14 days*
- The **incubation period (I-P)** for measles, from exposure to the onset of symptoms, typically ranges from **10 to 14 days**.
- This period includes the initial prodromal symptoms before the rash appears.
*Long term complication may be seen in form of SSPE*
- **Subacute sclerosing panencephalitis (SSPE)** is a rare, but fatal, **late complication** of measles infection [1].
- It results from persistent measles virus infection in the central nervous system, often developing years after the initial infection [1].
*Caused by RNA virus*
- Measles is caused by the **measles virus**, which is a **single-stranded RNA virus** belonging to the *Paramyxoviridae* family.
- It is an enveloped virus that primarily infects respiratory epithelial cells and replicates in lymphoid tissues.
*Rash appears first on face*
- The characteristic **maculopapular rash** of measles typically begins on the **face and behind the ears**.
- It then spreads downwards to the trunk and extremities, fading in the same order [1].
Air-Borne Diseases Indian Medical PG Question 6: Which of the following statements about the influenza virus is NOT true?
- A. Drift is the accumulation of point mutations.
- B. Only type A shows antigenic drift.
- C. All types exhibit antigenic shift. (Correct Answer)
- D. None of the above.
Air-Borne Diseases Explanation: ***All types exhibit antigenic shift.***
- This statement is **incorrect** (and thus the correct answer to this question asking for what is NOT true).
- **Antigenic shift** is a major genetic reassortment event that occurs primarily in **Influenza A virus**, where entire gene segments are exchanged between different strains, potentially leading to pandemic strains.
- **Influenza B** can undergo antigenic drift but does NOT typically exhibit antigenic shift due to its limited host range (primarily humans) and lack of reassortment opportunities.
- **Influenza C** causes mild respiratory illness and shows minimal antigenic variation.
*Only type A shows antigenic drift.*
- This statement is **false**. Both **Influenza A and Influenza B** undergo **antigenic drift**.
- Antigenic drift involves gradual accumulation of point mutations in hemagglutinin (HA) and neuraminidase (NA) genes, allowing immune evasion.
- This is why this is also an incorrect statement, but the question asks for one answer, and "all types exhibit shift" is the more clearly false statement.
*Drift is the accumulation of point mutations.*
- This statement is **true**.
- **Antigenic drift** results from **point mutations** in genes encoding surface proteins (HA and NA).
- These minor changes allow the virus to evade existing immunity, causing seasonal epidemics.
*None of the above.*
- This option is incorrect because there IS a false statement among the options ("All types exhibit antigenic shift").
Air-Borne Diseases Indian Medical PG Question 7: True about measles
- A. Long term complication follows in form of SSPE (Correct Answer)
- B. Rash appear first on leg
- C. Koplik spots are seen in retina
- D. Caused by DNA virus
Air-Borne Diseases Explanation: ***Long term complication follows in form of SSPE***
- **Subacute sclerosing panencephalitis (SSPE)** is a rare, but fatal, progressive neurodegenerative disease that can develop years after a measles infection [1].
- It is caused by persistent measles virus in the brain, leading to **neurological deterioration** and eventually death [2].
*Rash appear first on leg*
- The characteristic rash of measles typically appears first on the **face and behind the ears**, then spreads downward to the trunk and extremities [1].
- The rash is usually **maculopapular** and confluent, turning brownish and fading in the same order it appeared [1].
*Koplik spots are seen in retina*
- **Koplik spots** are pathognomonic for measles and are found on the **buccal mucosa** (inside the cheeks), opposite the molars [1].
- They appear as small, white, or bluish-white spots with an erythematous base before the onset of the rash.
*Caused by DNA virus*
- Measles is caused by the **measles virus**, which is a **single-stranded RNA virus** belonging to the genus *Morbillivirus* in the family *Paramyxoviridae*.
- It is not a DNA virus; this classification has significant implications for its replication cycle and vaccine development.
Air-Borne Diseases Indian Medical PG Question 8: A patient with TB on DOTS develops orange-red discoloration of urine and tears. Which drug is responsible?
- A. Ethambutol
- B. Rifampicin (Correct Answer)
- C. Pyrazinamide
- D. Isoniazid
Air-Borne Diseases Explanation: ***Rifampicin***
- **Rifampicin** is well-known for causing **orange-red discoloration** of urine, sweat, tears, and other body fluids due to its intrinsic color.
- This side effect is benign and does not indicate liver damage or other serious toxicity, but patients should be informed about it.
*Ethambutol*
- **Ethambutol** is primarily associated with **optic neuritis**, leading to decreased visual acuity and red-green color blindness.
- It does not cause discoloration of body fluids.
*Pyrazinamide*
- **Pyrazinamide** is commonly associated with **hepatotoxicity** and **hyperuricemia**, which can lead to gout.
- It does not cause discoloration of body fluids.
*Isoniazid*
- **Isoniazid** is known to cause **peripheral neuropathy** (prevented by pyridoxine supplementation) and **hepatotoxicity**.
- It does not cause discoloration of body fluids.
Air-Borne Diseases Indian Medical PG Question 9: Which immunization is typically given at 6 months of age?
- A. Measles vaccine
- B. DPT vaccine (Correct Answer)
- C. BCG vaccine
- D. None of the options
Air-Borne Diseases Explanation: **DPT vaccine**
- The DPT (diphtheria, pertussis, and tetanus) vaccine is administered in multiple doses during infancy as part of the primary immunization series.
- At **6 months of age**, the **third dose of DPT** is typically given (following doses at 6 weeks, 10 weeks, and 14 weeks according to the Indian immunization schedule).
- Among the options provided, DPT is the only vaccine routinely administered at 6 months of age.
- This vaccine protects against three serious bacterial infections: **diphtheria**, which can cause breathing problems; **pertussis (whooping cough)**, a severe respiratory illness; and **tetanus**, which causes painful muscle spasms.
*Measles vaccine*
- The measles vaccine (given as part of the **MMR vaccine** or as MR vaccine in India) is typically administered at **9 to 12 months of age** for the first dose, and a second dose between 15-18 months or 4-6 years.
- It is not routinely given at 6 months, as maternal antibodies can interfere with its effectiveness at this younger age.
*BCG vaccine*
- The BCG (Bacillus Calmette-Guérin) vaccine protects against **tuberculosis** and is given at **birth** or in early infancy as a single dose.
- It is not administered at 6 months of age.
*None of the options*
- This option is incorrect because the **DPT vaccine** (third dose) is a standard immunization given at 6 months of age according to the Indian immunization schedule.
- Multiple vaccines are actually given at 6 months (including OPV, Hepatitis B, Hib, PCV), but among the listed options, only DPT is correct.
Air-Borne Diseases Indian Medical PG Question 10: A child comes with fever, cold, cough, and a membrane over the tonsils; a nasal swab is taken. On which medium should the culture be done for the earliest diagnosis of diphtheria?
- A. L. J. media
- B. MC Conkey's Agar
- C. Citrate media
- D. Loffler's serum slope (Correct Answer)
Air-Borne Diseases Explanation: ***Loffler's serum slope***
- This medium promotes the rapid growth of *Corynebacterium diphtheriae*, allowing for early identification based on characteristic microscopic morphology within 6-8 hours.
- It enhances the production of **metachromatic granules** (Babes-Ernst bodies), which are key diagnostic features for diphtheria.
*L. J. media*
- **Lowenstein-Jensen (LJ) medium** is primarily used for the isolation and culture of **mycobacteria**, particularly *Mycobacterium tuberculosis*.
- It is not suitable for the rapid growth or specific identification of *Corynebacterium diphtheriae*.
*MC Conkey's Agar*
- **MacConkey agar** is a selective and differential medium used for the isolation and differentiation of **Gram-negative enteric bacilli**.
- It inhibits the growth of Gram-positive bacteria and is not appropriate for culturing *Corynebacterium diphtheriae*, which is Gram-positive.
*Citrate media*
- **Citrate media**, such as Simmons citrate agar, are used to test an organism's ability to utilize citrate as its sole source of carbon.
- This is a biochemical test for bacterial differentiation and not a primary isolation medium for *Corynebacterium diphtheriae*.
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