Non-Communicable Diseases — MCQs

Non-Communicable Diseases Indian Medical PG Practice Questions and MCQs

Question 221: What is the recommended duration of treatment for MDR/XDR tuberculosis?

A. 6 months
B. 12 months
C. 18 months
D. 24 months (Correct Answer)

Explanation: **Explanation:** The treatment of Drug-Resistant Tuberculosis (DR-TB) is significantly more complex and prolonged than drug-sensitive TB. According to the National Strategic Plan and WHO guidelines (NTEP), the standard duration for a **conventional MDR/XDR-TB regimen is 18 to 24 months**. In the context of NEET-PG, where a single duration is often sought, **24 months** is the established benchmark for the total duration (comprising 6–9 months of Intensive Phase and 18 months of Continuation Phase). **Why Option D is Correct:** MDR-TB (resistance to at least Isoniazid and Rifampicin) and XDR-TB (MDR plus resistance to a fluoroquinolone and at least one second-line injectable) require second-line drugs that are less potent and slower-acting. A duration of 24 months ensures complete sterilization of the slow-growing bacilli and prevents relapse. **Analysis of Incorrect Options:** * **Option A (6 months):** This is the standard duration for **Drug-Sensitive TB (DS-TB)** using the 2HREZ/4HR regimen. * **Option B (12 months):** While the newer "Shorter MDR-TB Regimen" (BPaL/BPaLM) can last 6–9 months, 12 months is not the standard for conventional MDR/XDR protocols. * **Option C (18 months):** This is the minimum duration for the Continuation Phase alone in conventional regimens; however, the *total* duration including the Intensive Phase extends to 24 months. **High-Yield Clinical Pearls for NEET-PG:** * **MDR-TB Definition:** Resistance to **H** (Isoniazid) and **R** (Rifampicin). * **Pre-XDR TB:** MDR-TB + resistance to any **Fluoroquinolone**. * **XDR-TB:** MDR-TB + resistance to any Fluoroquinolone + resistance to at least one **Group A drug** (Bedaquiline or Linezolid). * **BPaL Regimen:** A newer 6-month all-oral regimen (Bedaquiline, Pretomanid, Linezolid) is now being implemented for highly resistant cases, but 24 months remains the classic answer for conventional MDR/XDR-TB.

Question 222: What is the validity period of a certificate of yellow fever vaccination?

A. 10 days after date of vaccination up to 7 years
B. 10 days after date of vaccination up to 7 years
C. 10 days after date of vaccination up to 10 years (Correct Answer)
D. 7 days after date of vaccination up to 7 years

Explanation: **Explanation:** The validity of the International Certificate of Vaccination or Prophylaxis against Yellow Fever is a high-yield topic in Community Medicine. **1. Why Option C is correct:** According to the International Health Regulations (IHR), the certificate traditionally becomes valid **10 days** after the date of vaccination (the time required for protective antibody levels to develop) and lasts for a period of **10 years**. **Important Update for NEET-PG:** While the question reflects the traditional 10-year rule, the WHO amended the IHR in **July 2016**, stating that a single dose of Yellow Fever vaccine provides **life-long immunity**. Therefore, for international travel, the certificate is now technically valid for the life of the person vaccinated. However, in many exams, the "10 days to 10 years" rule is still frequently tested as the standard answer based on older textbook editions. **2. Why other options are incorrect:** * **Options A, B, and D:** These are incorrect because the minimum period for the development of immunity is 10 days, not 7. Furthermore, the 7-year duration has never been a standard for Yellow Fever; it is often confused with the validity of other vaccines or older quarantine protocols. **3. Clinical Pearls & High-Yield Facts:** * **Vaccine Strain:** 17D strain (Live attenuated). * **Route & Dose:** 0.5 ml, Subcutaneous. * **Contraindications:** Infants <6 months, egg allergy, and immunocompromised individuals. * **Quarantine:** If a traveler arrives from an endemic zone without a valid certificate, they are placed in mosquito-proof isolation for **6 days** (the incubation period of the disease). * **Validity of Re-vaccination:** If a person is re-vaccinated before the expiry of the previous certificate, the new certificate becomes valid **immediately** on that day (no 10-day wait).

Question 223: El Tor Vibrio can be differentiated from classical Vibrio by the fact that El Tor Vibrio:

A. Agglutinates chicken and sheep erythrocytes
B. Is resistant to classical phage IV
C. Is resistant to polymyxin B-50 unit disc
D. All of the above (Correct Answer)

Explanation: The differentiation between the **Classical** and **El Tor** biotypes of *Vibrio cholerae* (Serogroup O1) is a high-yield topic in Community Medicine and Microbiology. While both cause clinical cholera, they exhibit distinct laboratory characteristics. ### **Explanation of the Correct Answer (D)** The correct answer is **All of the above** because El Tor Vibrio possesses specific phenotypic traits that distinguish it from the Classical biotype: 1. **Haemagglutination (Option A):** El Tor Vibrio has the ability to agglutinate red blood cells (RBCs) of chickens and sheep. The Classical biotype typically does not show this property. 2. **Phage Susceptibility (Option B):** In the Mukerjee phage typing system, El Tor is **resistant** to Group IV bacteriophage, whereas the Classical biotype is sensitive. 3. **Polymyxin B Resistance (Option C):** El Tor is **resistant** to Polymyxin B (using a 50-unit disc), while the Classical biotype is sensitive and shows a zone of inhibition. ### **Why other options are considered together** Since El Tor satisfies all three laboratory criteria mentioned above, selecting any single option would be incomplete. Modern diagnostic protocols use these tests collectively to confirm the biotype during epidemiological surveillance. ### **High-Yield Clinical Pearls for NEET-PG** * **Voges-Proskauer (VP) Test:** El Tor is usually **VP positive** (produces acetylmethylcarbinol), while Classical is VP negative. * **Hemolysis:** El Tor is typically **haemolytic** (Greig test), whereas Classical is non-haemolytic. * **Epidemiology:** The **7th Pandemic** was caused by the El Tor biotype. It is more "hardy," survives longer in the environment, and causes a higher ratio of asymptomatic carriers to clinical cases (up to 100:1) compared to the Classical biotype. * **Current Status:** The Classical biotype is now largely extinct worldwide, except for sporadic isolations in Bangladesh.

Question 224: Herd immunity is not important in which of the following?

A. Tetanus (Correct Answer)
B. Pertussis
C. Diphtheria
D. All

Explanation: **Explanation:** The concept of **Herd Immunity** (Community Immunity) refers to the indirect protection from an infectious disease that happens when a large percentage of a population becomes immune, thereby stopping the chain of transmission. **1. Why Tetanus is the Correct Answer:** Herd immunity applies only to diseases that spread from **person to person**. Tetanus is caused by *Clostridium tetani* spores found in the soil and environment. It is acquired through direct contact with contaminated wounds, not through human transmission. Therefore, even if 99% of the population is vaccinated, the remaining 1% remains at risk if they sustain a dirty injury. There is no "chain of transmission" to break; hence, herd immunity does not exist for Tetanus. **2. Why the Other Options are Incorrect:** * **Pertussis (Whooping Cough):** This is a highly contagious respiratory infection spread via droplets. Vaccination reduces the reservoir of *Bordetella pertussis* in the community, protecting unvaccinated infants through herd immunity. * **Diphtheria:** Caused by *Corynebacterium diphtheriae*, it spreads through respiratory droplets or direct contact. High vaccine coverage (DPT) reduces the carrier state and transmission, providing herd immunity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Prerequisite for Herd Immunity:** The disease agent must be restricted to a single host species (humans) and have a direct transmission mechanism. * **Tetanus Exception:** Tetanus is the classic example of a vaccine-preventable disease where **individual protection** is the only safeguard. * **Eradication vs. Elimination:** Herd immunity is essential for the eradication of diseases like Smallpox and Polio. Since the environmental reservoir for Tetanus cannot be eliminated, Tetanus can be **eliminated** (e.g., Neonatal Tetanus) but never **eradicated**.

Question 225: For the field diagnosis of trachoma, the WHO recommends that follicular and intense trachoma inflammation should be assessed in which age group?

A. Women aged 15-45 years
B. Population aged 10 to 28 years
C. Children aged 0-10 years (Correct Answer)
D. Population above 25 years of age irrespective of sex

Explanation: ### Explanation **Correct Answer: C. Children aged 0-10 years** **1. Why it is correct:** Trachoma, caused by *Chlamydia trachomatis*, is the leading infectious cause of blindness worldwide. For epidemiological surveillance and field diagnosis, the WHO focuses on the **0–10 year age group** (specifically children aged 1–9 years) to assess the prevalence of active disease. This group represents the **reservoir of infection** where active inflammatory signs—**Trachomatous inflammation—Follicular (TF)** and **Trachomatous inflammation—Intense (TI)**—are most prevalent. Monitoring this cohort allows health authorities to determine if the community requires mass drug administration (MDA) with Azithromycin. **2. Why the other options are incorrect:** * **Option A & D:** While adult women and older populations are at the highest risk for **Trachomatous Trichiasis (TT)** and corneal scarring due to repeated childhood infections, they are not the primary group used for diagnosing the *active* transmission of the disease in a community. * **Option B:** The age range of 10–28 years is too broad and misses the peak window of active follicular infection, which typically declines after age 10 as immunity develops. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **WHO SAFE Strategy:** **S**urgery (for trichiasis), **A**ntibiotics (Azithromycin), **F**acial cleanliness, and **E**nvironmental improvement. * **WHO Simplified Grading System (FISTO):** * **TF:** 5 or more follicles (>0.5mm) on the upper tarsal conjunctiva. * **TI:** Thickening obscuring >50% of deep tarsal vessels. * **TS:** Trachomatous Scarring. * **TT:** Trachomatous Trichiasis (at least one lash rubbing the eyeball). * **CO:** Corneal Opacity. * **Elimination Threshold:** Prevalence of TF in children aged 1–9 years must be **<5%** to indicate elimination as a public health problem.

Question 226: What is considered a definite case of Polio?

A. Paralysis lasting more than 6 weeks
B. Antibody titre more than 4 times the normal value
C. Demonstration of Polio virus in stool (Correct Answer)
D. Acute encephalitis with paralysis

Explanation: ### Explanation In the context of the Global Polio Eradication Initiative, the definition of a "confirmed" or "definite" case of poliomyelitis has evolved from clinical criteria to virological confirmation. **Why Option C is Correct:** The gold standard for diagnosing a definite case of polio is the **isolation and demonstration of wild poliovirus in the stool**. According to WHO protocols, a case is confirmed if wild poliovirus is isolated from stool samples of a patient with Acute Flaccid Paralysis (AFP). Ideally, two "adequate" stool samples must be collected 24–48 hours apart within 14 days of the onset of paralysis. **Analysis of Incorrect Options:** * **Option A:** Residual paralysis lasting more than 6 weeks was part of the **clinical case definition** used before the virological era. While suggestive, it is not definitive as other conditions (like GBS) can cause lasting paralysis. * **Option B:** While a rise in antibody titer indicates infection, it is not used for "definite" case confirmation in surveillance programs because it cannot distinguish between wild virus infection, vaccine-derived virus, or previous immunization. * **Option C:** Polio primarily manifests as **Acute Flaccid Paralysis (AFP)**, not encephalitis. Encephalitis involves the brain parenchyma and presents with altered sensorium, which is atypical for classic spinal polio. **High-Yield Clinical Pearls for NEET-PG:** * **AFP Surveillance:** The most sensitive tool for detecting polio. The target non-polio AFP rate should be **>2 per 100,000 children** under 15 years. * **VAPP vs. VDPV:** Vaccine-Associated Paralytic Polio (VAPP) occurs in the vaccine recipient; Vaccine-Derived Poliovirus (VDPV) is a mutated strain circulating in the community. * **Last Case in India:** Reported on **January 13, 2011**, in Howrah, West Bengal. India was declared Polio-free on **March 27, 2014**. * **Stool Sample Storage:** Samples must be sent under "reverse cold chain" (maintained at 2–8°C).

Question 227: Growth rate is calculated by?

A. Crude birth rate / Crude death rate
B. Net reproduction rate - Crude death rate
C. Total fertility rate - Crude death rate
D. Crude birth rate - Crude death rate (Correct Answer)

Explanation: **Explanation** The **Growth Rate** (specifically the Natural Increase Rate) of a population is the difference between the number of live births and the number of deaths occurring in a year, expressed per 1,000 population. **1. Why Option D is Correct:** The fundamental formula for natural population growth is: **Growth Rate = Crude Birth Rate (CBR) - Crude Death Rate (CDR)** This represents the "natural increase" of a population. When expressed as a percentage, it is calculated as: $\frac{CBR - CDR}{10}$. It reflects how much a population is expanding or contracting based solely on vital events, excluding migration. **2. Why Other Options are Incorrect:** * **Option A:** Dividing CBR by CDR does not yield a standard demographic rate; it would merely provide a ratio of births to deaths. * **Option B:** **Net Reproduction Rate (NRR)** measures the number of daughters a newborn girl will bear during her lifetime. Subtracting CDR from NRR is mathematically incorrect as they use different denominators and represent different concepts. * **Option C:** **Total Fertility Rate (TFR)** is the average number of children a woman would have if she survives to the end of her reproductive years. It is a cohort measure, whereas CDR is a period measure; they cannot be directly subtracted to find the growth rate. **3. High-Yield Clinical Pearls for NEET-PG:** * **Demographic Transition Model:** India is currently in **Stage 3** (Late expanding), characterized by a falling birth rate and a low death rate. * **Vital Statistics:** The CBR and CDR are "crude" because they do not account for the age or sex structure of the population. * **Replacement Level Fertility:** An **NRR of 1** (or TFR of 2.1) is the target for population stabilization. * **Rule of 70:** To calculate the **doubling time** of a population, divide 70 by the annual growth rate percentage.

Question 228: Post-exposure measles vaccine must be given within how many days of exposure?

A. 1 day
B. 3 days (Correct Answer)
C. 7 days
D. 10 days

Explanation: **Explanation:** **1. Why 3 days is correct:** The measles vaccine is highly effective as post-exposure prophylaxis (PEP) if administered within **72 hours (3 days)** of exposure. This is because the incubation period of measles is relatively long (typically 10–14 days). Administering the live-attenuated vaccine early induces an immune response faster than the natural virus can replicate and cause disease, effectively preventing or significantly modifying the clinical course of the infection. **2. Why other options are incorrect:** * **1 day:** While giving the vaccine within 24 hours is excellent, the window of efficacy extends up to 3 days. * **7 and 10 days:** By this stage, the virus has already undergone significant replication and primary viremia. The vaccine will no longer be effective in preventing the disease. For individuals exposed more than 3 days ago but less than 6 days ago, **Immunoglobulin (IG)** is the preferred intervention instead of the vaccine. **3. High-Yield Clinical Pearls for NEET-PG:** * **Vaccine vs. Immunoglobulin:** * Vaccine: Within **3 days** (72 hours). * Immunoglobulin (IG): Within **6 days**. * **Dosage of IG:** 0.25 mL/kg (Standard) or 0.5 mL/kg in immunocompromised children (Max dose 15 mL). * **Contraindication:** If IG is given, the MMR/Measles vaccine must be delayed by **8 to 11 months** to avoid interference with the immune response. * **Incubation Period:** 10 days to onset of fever; 14 days to onset of rash. * **Infectivity:** 4 days before to 4 days after the appearance of the rash.

Question 229: In cases of sexually transmitted diseases (STDs), a patient is asked to name other persons in his socio-sexual group, who are then investigated. This is an example of:

A. Screening
B. Contact tracing (Correct Answer)
C. Mass screening
D. High-risk screening

Explanation: ### Explanation **Correct Answer: B. Contact tracing** **Why it is correct:** Contact tracing is a fundamental public health strategy used to identify, assess, and manage individuals who have been exposed to an infectious disease to prevent further transmission. In the context of STDs, it involves identifying the "index case" and then locating their sexual partners or members of their socio-sexual group. This process is essential because many STDs are asymptomatic; by tracing contacts, healthcare providers can diagnose and treat infected individuals who might otherwise continue the chain of transmission. **Why incorrect options are wrong:** * **A. Screening:** This is the presumptive identification of unrecognized disease in an **apparently healthy** population using tests or examinations. It is a broader proactive approach, whereas contact tracing is reactive to a known case. * **C. Mass screening:** This involves screening the **entire population** (e.g., everyone in a city), regardless of their risk profile or exposure history. * **D. High-risk screening:** This targets specific groups known to have a higher prevalence of disease (e.g., screening commercial sex workers for HIV). While contact tracing deals with high-risk individuals, it specifically targets those with **known exposure** to a confirmed case. **High-Yield Clinical Pearls for NEET-PG:** * **Contact Tracing** is most effective for diseases with a low prevalence, long incubation period, and high infectivity (e.g., Syphilis, Tuberculosis, and COVID-19). * **Partner Notification:** This is a specific form of contact tracing used in STD management. * **Epidemiological Treatment:** In some STDs (like Gonorrhea), contacts are treated even before test results are available to break the chain of transmission immediately. * **The "Iceberg Phenomenon":** Contact tracing helps uncover the "submerged" portion of the iceberg (asymptomatic/undiagnosed cases) in the community.

Question 230: Scrub typhus is caused by which of the following vectors?

A. Mite (Correct Answer)
B. Louse
C. Tick
D. Flea

Explanation: **Explanation:** **Scrub Typhus** (also known as Tsutsugamushi disease) is a zoonotic rickettsial infection caused by the bacterium ***Orientia tsutsugamushi***. 1. **Why Mite is Correct:** The disease is transmitted to humans through the bite of the larval stage (known as **chiggers**) of trombiculid mites, specifically *Leptotrombidium deliense*. These mites serve as both the vector and the reservoir (via transovarial transmission). The infection is typically characterized by a necrotic skin lesion called an **eschar** at the site of the bite. 2. **Why Other Options are Incorrect:** * **Louse:** Transmits **Epidemic Typhus** (*Rickettsia prowazekii*). * **Tick:** Transmits **Rocky Mountain Spotted Fever** (*R. rickettsii*) and **Indian Tick Typhus** (*R. conorii*). * **Flea:** Transmits **Endemic (Murine) Typhus** (*R. typhi*). **High-Yield Clinical Pearls for NEET-PG:** * **The Eschar:** A "punched-out" ulcer with a black crust; it is the most pathognomonic clinical sign of Scrub Typhus. * **Habitat:** Often found in "scrub" vegetation (secondary growth of grass/shrubs), hence the name. * **Diagnosis:** The **Weil-Felix test** shows agglutination with **OX-K** strain (negative for OX-19 and OX-2). However, the Gold Standard is the Indirect Immunofluorescence Assay (IFA). * **Treatment:** **Doxycycline** is the drug of choice for all age groups. Azithromycin is an alternative, especially in pregnancy.

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