Non-Communicable Diseases — MCQs

Non-Communicable Diseases Indian Medical PG Practice Questions and MCQs

Question 301: What is true regarding antigenic shift?

A. Gradual changes
B. Seen in influenza A and B
C. Due to genetic recombination (Correct Answer)
D. Due to point mutation

Explanation: **Explanation:** The concept of antigenic variation in the Influenza virus is a high-yield topic for NEET-PG, categorized into two types: **Antigenic Shift** and **Antigenic Drift**. **Why the correct answer is right:** **Antigenic Shift** refers to an abrupt, major change in the virus resulting in new Hemagglutinin (H) and/or Neuraminidase (N) proteins. This occurs due to **genetic recombination** (specifically **reassortment**) of genetic segments between two or more different influenza strains infecting the same cell. Because the population has little to no immunity against this new subtype, it often leads to **Pandemics**. **Analysis of Incorrect Options:** * **A. Gradual changes:** This describes Antigenic Drift, which involves slow, continuous changes over time. * **B. Seen in influenza A and B:** Antigenic Shift occurs **only in Influenza A** because it has a broad host range (humans, birds, pigs), allowing for reassortment. Influenza B only undergoes Drift. * **D. Due to point mutation:** This is the mechanism for **Antigenic Drift**. Point mutations in the RNA lead to minor changes in the surface antigens, necessitating the update of annual flu vaccines. **High-Yield Clinical Pearls for NEET-PG:** * **Shift = Pandemic:** Sudden, major change, Influenza A only, reassortment. * **Drift = Epidemic:** Gradual, minor change, Influenza A and B, point mutation. * **Host for Shift:** The pig is often called the "mixing vessel" for antigenic shift between avian and human influenza viruses. * **Vaccine Strain:** The WHO reviews the vaccine composition annually primarily due to Antigenic Drift.

Question 302: Which of the following diseases is notifiable internationally?

A. Cholera (Correct Answer)
B. Relapsing fever
C. Influenza
D. Louse borne typhus

Explanation: **Explanation:** The concept of "Notifiable Diseases" under the **International Health Regulations (IHR 2005)** is a high-yield topic for NEET-PG. According to the IHR (2005), there are specific diseases that must be notified to the World Health Organization (WHO) because they constitute a Public Health Emergency of International Concern (PHEIC). **1. Why Cholera is Correct:** Under the current IHR (2005), **Cholera**, **Plague**, and **Yellow Fever** are specifically listed as diseases that are "special causes for concern." These diseases have a high potential for international spread and require immediate notification to the WHO if a single case occurs, as they can trigger a PHEIC. **2. Analysis of Incorrect Options:** * **Relapsing Fever (B) and Louse-borne Typhus (D):** These were previously considered "Quarantinable diseases" under the older IHR (1969). However, in the updated IHR (2005), they are no longer listed as internationally notifiable diseases, though they remain important for national surveillance. * **Influenza (C):** While "Human influenza caused by a new subtype" (like H5N1 or pandemic strains) is notifiable, seasonal influenza is not. Since the option only mentions "Influenza," it is less specific than Cholera. **Clinical Pearls for NEET-PG:** * **IHR 2005 Mandatory Notifications:** Always notify WHO for: Smallpox, Poliomyelitis (wild-type), Human Influenza (new subtype), and SARS. * **The "Big Three":** Historically and practically, Cholera, Plague, and Yellow Fever remain the core focus of international quarantine and notification. * **National vs. International:** Do not confuse "Internally Notifiable" (state/national level) with "Internationally Notifiable" (WHO level). Cholera is both.

Question 303: Tuberculin test denotes?

A. Previous or present sensitivity to tubercle proteins (Correct Answer)
B. Patient is resistant to tuberculosis
C. Person is susceptible to tuberculosis
D. Protective immune status of individual against tuberculosis

Explanation: ### Explanation The **Tuberculin Skin Test (TST)**, also known as the Mantoux test, is based on a **Type IV (Delayed-type) Hypersensitivity reaction**. When Purified Protein Derivative (PPD) is injected intradermally, it triggers a response in individuals whose T-lymphocytes have been previously sensitized to the antigens of *Mycobacterium tuberculosis*. **Why Option A is correct:** A positive test (induration of $\geq$ 10 mm in most cases) indicates that the individual’s immune system has recognized the tubercle proteins. This sensitivity occurs due to a **past or present infection** with *M. tuberculosis*. It does not distinguish between a latent infection and active disease; it merely confirms that the body has encountered the pathogen before. **Why other options are incorrect:** * **Option B & D:** A positive TST does **not** imply immunity or resistance. Unlike some viral antibodies, the presence of delayed hypersensitivity to PPD does not correlate with clinical protection against the disease. * **Option C:** A negative test does not necessarily mean a person is "susceptible" in a clinical sense; it simply means they have not been infected yet (or are in the pre-allergic window period of 2–10 weeks). **High-Yield Clinical Pearls for NEET-PG:** * **Reading the test:** The result is read after **48–72 hours**. Only the **induration** (palpable hardness) is measured, not the erythema (redness). * **False Positives:** Can occur due to prior **BCG vaccination** or infection with Non-Tuberculous Mycobacteria (NTM). * **False Negatives (Anergy):** Seen in severe malnutrition, miliary TB, HIV/AIDS, or recent viral infections (e.g., Measles). * **Standard Dose:** 0.1 ml of PPD containing **5 Tuberculin Units (TU)** is injected on the volar aspect of the forearm.

Question 304: All of the following are true regarding primary prevention EXCEPT?

A. Immunization
B. Specific protection
C. Early diagnosis and treatment (Correct Answer)
D. Contraceptives

Explanation: ### Explanation The concept of **Levels of Prevention** is a high-yield topic in Community Medicine. To answer this question, one must distinguish between actions taken before the onset of disease versus those taken after the disease process has started. **Why "Early diagnosis and treatment" is the correct answer:** Early diagnosis and treatment (e.g., sputum microscopy for TB or Pap smears for cervical cancer) constitute **Secondary Prevention**. The goal here is to arrest the disease process, prevent complications, and limit the spread of infectious agents. Since the question asks for the "EXCEPT" regarding Primary Prevention, this is the correct choice. **Analysis of Incorrect Options (Primary Prevention):** Primary prevention aims to prevent the initiation of a disease through two main modes of intervention: * **Health Promotion:** Includes health education, environmental modifications, and lifestyle changes. * **Specific Protection:** Includes **Immunization (Option A)**, the use of **Contraceptives (Option D)** to prevent pregnancy, and chemoprophylaxis. * **Option B** is a direct category of Primary Prevention. **NEET-PG High-Yield Pearls:** 1. **Primordial Prevention:** Action taken to prevent the emergence of risk factors (e.g., discouraging children from starting smoking). It deals with "underlying conditions" rather than specific risk factors. 2. **Primary Prevention:** Action taken *before* the onset of disease (Pre-pathogenesis phase). It lowers the **incidence** of disease. 3. **Secondary Prevention:** Action taken in the *early pathogenesis* phase. It lowers the **prevalence** of disease. 4. **Tertiary Prevention:** Includes disability limitation and rehabilitation (Pathogenesis phase).

Question 305: Which of the following diseases is NOT transmitted by mosquitoes?

A. Dengue
B. Malaria
C. Relapsing fever (Correct Answer)
D. Yellow fever

Explanation: **Explanation:** The correct answer is **Relapsing fever** because it is not a mosquito-borne disease. Relapsing fever is caused by spirochetes of the genus *Borrelia* and is transmitted via two primary vectors: 1. **Louse-borne relapsing fever (LBRF):** Transmitted by the human body louse (*Pediculus humanus corporis*). 2. **Tick-borne relapsing fever (TBRF):** Transmitted by soft-bodied ticks of the genus *Ornithodoros*. **Analysis of Incorrect Options:** * **Dengue:** Caused by the Dengue virus (Flavivirus) and transmitted primarily by the **_Aedes aegypti_** mosquito. * **Malaria:** Caused by *Plasmodium* parasites and transmitted by the bite of an infected female **_Anopheles_** mosquito. * **Yellow fever:** An acute viral hemorrhagic disease transmitted by **_Aedes_** and *Haemagogus* species of mosquitoes. **High-Yield Clinical Pearls for NEET-PG:** * **Vector Identification:** Remember the "Big Five" mosquito-borne diseases: Malaria, Filariasis, Dengue, Chikungunya, and Japanese Encephalitis. * **Louse-borne diseases:** Apart from Relapsing fever, the body louse also transmits **Epidemic Typhus** (*Rickettsia prowazekii*) and **Trench Fever** (*Bartonella quintana*). * **Relapsing Fever Mechanism:** The characteristic "relapsing" fever is due to **antigenic variation** of the *Borrelia* surface proteins, allowing the pathogen to evade the host's immune system repeatedly. * **Drug of Choice:** Tetracyclines (like Doxycycline) are generally the treatment of choice for Relapsing fever; however, be alert for the **Jarisch-Herxheimer reaction** following the first dose.

Question 306: Which of the following is the best indicator of cardiovascular disease risk?

A. Skin fold thickness
B. Waist to hip ratio (Correct Answer)
C. Waist circumference
D. Body Mass Index (BMI)

Explanation: **Explanation:** The **Waist-to-Hip Ratio (WHR)** is considered the best clinical indicator of cardiovascular disease (CVD) risk among the given options because it specifically measures **central (android) obesity**. Unlike total body fat, visceral fat stored in the abdominal region is metabolically active and strongly associated with insulin resistance, dyslipidemia, and systemic inflammation—the primary drivers of atherosclerosis and coronary heart disease. **Analysis of Options:** * **Waist-to-Hip Ratio (WHR):** It reflects the distribution of fat. A WHR >0.9 in men and >0.85 in women is a significant predictor of myocardial infarction and metabolic syndrome. * **Body Mass Index (BMI):** While widely used, BMI is a measure of "excess weight" rather than "excess fat." It cannot distinguish between muscle mass and adipose tissue, nor does it account for fat distribution. * **Waist Circumference (WC):** This is a good indicator of abdominal fat, but it does not account for the individual’s overall body frame or pelvic structure as accurately as the ratio does. * **Skinfold Thickness:** This measures subcutaneous fat (fat under the skin) using calipers. While useful for estimating total body fat percentage, it is less predictive of internal visceral fat and long-term cardiovascular outcomes. **High-Yield Clinical Pearls for NEET-PG:** * **WHO Cut-offs for WHR:** >0.90 (Males) and >0.85 (Females) indicate abdominal obesity. * **Metabolic Syndrome (ATP III Criteria):** Waist circumference is the preferred parameter (>102 cm in men, >88 cm in women; for Asians, it is >90 cm in men and >80 cm in women). * **Ponderal Index:** $Weight / Height^3$; used primarily in neonatology to assess intrauterine growth retardation. * **Quetelet’s Index:** Another name for BMI ($Weight / Height^2$).

Question 307: Based on epidemiological studies, which of the following has been found to be most protective against colon cancer?

A. High fiber diet (Correct Answer)
B. Low fat diet
C. Low selenium diet
D. Low protein diet

Explanation: **Explanation:** The relationship between diet and colorectal cancer is a high-yield topic in Community Medicine. **1. Why "High fiber diet" is correct:** Epidemiological studies consistently show that a high-fiber diet (found in fruits, vegetables, and whole grains) is the most significant protective factor against colon cancer. The underlying medical mechanisms include: * **Dilution:** Fiber increases fecal bulk, diluting potential carcinogens in the colon. * **Transit Time:** It speeds up the passage of stool, reducing the time the colonic mucosa is exposed to harmful substances. * **Fermentation:** Gut bacteria ferment fiber into short-chain fatty acids (like butyrate), which have anti-inflammatory and anti-neoplastic properties. **2. Analysis of Incorrect Options:** * **Low fat diet:** While high intake of saturated animal fats is a known *risk factor* (as it increases bile acid secretion which can be converted into carcinogens), the protective effect of reducing fat is statistically less robust than the protective effect of increasing fiber. * **Low selenium diet:** This is incorrect because Selenium is actually an antioxidant. Therefore, a **high** selenium intake (not low) is considered protective against various cancers. * **Low protein diet:** There is no strong evidence that a low-protein diet is protective. However, a diet high in **red meat and processed meats** is a significant risk factor for colon cancer. **3. NEET-PG High-Yield Pearls:** * **Most common site of Colon Cancer:** Sigmoid colon (globally), though the incidence of right-sided (ascending) colon cancer is rising. * **Dietary Risk Factors:** High intake of red meat (beef, lamb), processed meat, and alcohol. * **Protective Factors:** High fiber, Calcium, Vitamin D, and regular physical activity. * **Gold Standard Screening:** Colonoscopy every 10 years, starting at age 45 (as per recent guidelines).

Question 308: What is the protective value of a vaccine when it is stated to be 95%?

A. All individuals who receive the vaccine are completely protected.
B. 95% of vaccinated individuals are immune to the disease.
C. 95% of vaccinated individuals will not contract the disease, while 5% will.
D. There is a 5% probability that a vaccinated individual will get infected. (Correct Answer)

Explanation: ### Explanation **Concept of Vaccine Efficacy/Protective Value** The protective value (efficacy) of a vaccine refers to the proportionate reduction in disease incidence among vaccinated individuals compared to unvaccinated individuals under ideal conditions. It is calculated using the formula: **Vaccine Efficacy = [ (ARU – ARV) / ARU ] × 100** *(Where ARU = Attack Rate in Unvaccinated; ARV = Attack Rate in Vaccinated)* When a vaccine has a 95% protective value, it means the vaccine reduces the risk of disease by 95%. Conversely, there remains a **residual risk of 5%**. Therefore, any single vaccinated individual still carries a 5% probability of contracting the infection if exposed. **Analysis of Options:** * **Option D (Correct):** This accurately reflects the individual risk. If the vaccine is 95% effective, the "failure rate" is 5%, meaning a 5% chance of infection remains. * **Option A:** Incorrect. No vaccine is 100% effective; there are always primary vaccine failures (failure to seroconvert) or secondary failures (waning immunity). * **Option B:** Incorrect. Immunity is a biological state, while protective value is a statistical measure of disease reduction. 95% efficacy does not mean exactly 95% of people are "immune"; some may have low titers but still be protected from severe disease. * **Option C:** Incorrect. This is a common misconception. Efficacy describes a **reduction in risk**, not a fixed census of who will or will not get sick, as the outcome also depends on the force of infection in the community. **High-Yield Clinical Pearls for NEET-PG:** 1. **Vaccine Effectiveness:** Refers to how the vaccine performs in "real-world" field conditions (includes storage, handling, and provider factors). 2. **Cold Chain:** The most critical factor in maintaining the protective value of live vaccines (e.g., OPV, Measles). 3. **Herd Immunity Threshold:** Calculated as **$H = 1 - (1/R_0)$**. To achieve herd immunity, the percentage of the population immune must exceed this threshold.

Question 309: A 30-year-old female has sputum-positive tuberculosis. Her child is 3 years old. What is the recommended chemoprophylaxis for the child?

A. Isoniazid (INH) 3 mg/kg for 3 months
B. Isoniazid (INH) 5 mg/kg for 3 months
C. Isoniazid (INH) 3 mg/kg for 6 months
D. Isoniazid (INH) 5 mg/kg for 6 months (Correct Answer)

Explanation: **Explanation** The correct answer is **D. Isoniazid (INH) 5 mg/kg for 6 months.** **1. Underlying Medical Concept** Under the National Tuberculosis Elimination Program (NTEP) guidelines, chemoprophylaxis is indicated for household contacts of a sputum-positive pulmonary TB patient who are at high risk of developing the disease. Children **under 6 years of age** are particularly vulnerable. Once active TB is ruled out in the child, they should receive **Isoniazid Preventive Therapy (IPT)**. The standard regimen is **5 mg/kg body weight of Isoniazid daily for a duration of 6 months**. This prevents the progression of latent infection to active disease. **2. Analysis of Incorrect Options** * **Options A & B (3 months):** A 3-month duration is insufficient for standard Isoniazid monotherapy. While shorter regimens (like 3 months of Rifampicin + Isoniazid) exist in some international guidelines, the standard IPT duration in India remains 6 months. * **Option C (3 mg/kg):** The dose of 3 mg/kg is sub-therapeutic for children. The recommended pediatric dose for prophylaxis is 5 mg/kg (up to a maximum of 300 mg/day). **3. High-Yield Clinical Pearls for NEET-PG** * **Target Group:** All household contacts <6 years of age of a smear-positive index case, regardless of their BCG vaccination status. * **HIV Patients:** All HIV-infected individuals (adults and children) should receive IPT for 6 months after ruling out active TB. * **Pyridoxine (Vitamin B6):** Should be co-administered (10 mg/day) with INH to prevent peripheral neuropathy, especially in malnourished children or those with HIV. * **Newer Guidelines (3HP):** Note that NTEP is transitioning towards shorter regimens like **3HP** (once-weekly Isoniazid and Rifapentine for 12 weeks) for TB Preventive Treatment (TPT) in certain populations.

Question 310: What is the recommended duration of daily moderate exercise for an adult?

A. 15 minutes
B. 30 minutes (Correct Answer)
C. 45 minutes
D. 60 minutes

Explanation: **Explanation:** The correct answer is **30 minutes (Option B)**. This recommendation is based on the World Health Organization (WHO) and the National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke (NPCDCS) guidelines for physical activity in adults (18–64 years). **Why 30 minutes is correct:** To maintain cardiovascular health and reduce the risk of non-communicable diseases (NCDs) like hypertension and Type 2 Diabetes, adults are advised to engage in at least **150 minutes of moderate-intensity aerobic physical activity throughout the week**. When distributed over 5 days a week, this equates to **30 minutes per day**. Moderate-intensity exercise is defined as activity that noticeably increases heart rate and breathing (e.g., brisk walking). **Analysis of Incorrect Options:** * **Option A (15 minutes):** This duration is insufficient to meet the minimum metabolic equivalent (MET) requirements for significant chronic disease prevention. * **Option C (45 minutes):** While beneficial, this exceeds the minimum baseline recommendation for general health maintenance. * **Option D (60 minutes):** This is the specific recommendation for **children and adolescents (5–17 years)**, who require more activity for healthy growth and development. **NEET-PG High-Yield Pearls:** * **Vigorous Intensity:** If the exercise is vigorous (e.g., running), the recommendation is **75 minutes per week** (approx. 15 mins/day). * **Muscle Strengthening:** Should be done involving major muscle groups on **2 or more days** a week. * **Sedentary Behavior:** The latest guidelines emphasize "Every move counts" to offset the risks of prolonged sitting. * **Weight Loss:** For additional health benefits or weight loss, the duration should ideally be increased to 300 minutes of moderate activity per week.

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