Non-Communicable Diseases — MCQs

Non-Communicable Diseases Indian Medical PG Practice Questions and MCQs

Question 401: Which of the following is a true statement regarding the tuberculin test?

A. Used for the definitive diagnosis of active tuberculosis
B. Measures the incidence of tuberculosis infection in a population
C. An induration of more than 10 mm after 72 hours indicates a positive test (Correct Answer)
D. Measures the level of acquired immunity against tuberculosis

Explanation: **Explanation:** The Tuberculin Skin Test (TST), or Mantoux test, is a classic example of a **Type IV (Delayed-type) Hypersensitivity reaction**. It utilizes Purified Protein Derivative (PPD) to detect cell-mediated immunity against *Mycobacterium tuberculosis*. **1. Why Option C is Correct:** The test is read **48 to 72 hours** after the intradermal injection of 5 TU (Tuberculin Units) of PPD. The result is determined by measuring the **transverse diameter of induration** (palpable hardening), not erythema. In India and most high-prevalence settings, an induration of **≥10 mm** is considered a positive result, indicating prior exposure or infection. **2. Why Other Options are Incorrect:** * **Option A:** TST is a screening tool for infection, not a definitive diagnostic test for active disease. Definitive diagnosis requires sputum microscopy, culture, or CBNAAT (GeneXpert). * **Option B:** TST measures the **prevalence** of tuberculosis infection (the total pool of infected individuals) and the **Annual Risk of Tuberculosis Infection (ARTI)**, but it does not measure the *incidence* (new cases of active disease) in a population. * **Option D:** A positive TST indicates **hypersensitivity** to the tubercle bacilli; it does **not** correlate with the level of protective immunity or the likelihood of developing active disease. **High-Yield Clinical Pearls for NEET-PG:** * **False Negatives:** Can occur in severe malnutrition, miliary TB, HIV/AIDS (CD4 <200), and recent viral infections (e.g., Measles). * **False Positives:** Can occur due to prior BCG vaccination or exposure to Non-Tuberculous Mycobacteria (NTM). * **Cut-off variations:** In HIV-positive individuals, an induration of **≥5 mm** is considered positive. * **Standard Dose:** 0.1 ml of PPD (5 TU) injected intradermally on the volar aspect of the forearm.

Question 402: Which of the following statements about polio vaccination is NOT true?

A. Follow-up of acute flaccid paralysis (AFP) for 30 days. (Correct Answer)
B. The Salk vaccine contains all three types of poliovirus.
C. Pulse polio doses are given in addition to routine immunization.
D. The oral polio vaccine also provides intestinal immunity.

Explanation: **Explanation:** The correct answer is **A**. In the Global Polio Eradication Initiative, the standard protocol for the follow-up of **Acute Flaccid Paralysis (AFP)** cases is **60 days**, not 30 days. If a child presents with AFP, a clinical examination must be repeated after 60 days to check for residual paralysis, which helps differentiate poliomyelitis from other transient causes of paralysis. **Analysis of other options:** * **Option B:** The Salk vaccine (Inactivated Polio Vaccine - IPV) is a trivalent vaccine containing inactivated (killed) strains of poliovirus types 1, 2, and 3. * **Option C:** Pulse Polio Immunization (PPI) is a mass campaign strategy where extra doses of OPV are administered to all children under 5 years, regardless of their previous routine immunization status. These are "supplementary" doses. * **Option D:** The Oral Polio Vaccine (OPV) is a live-attenuated vaccine that replicates in the gut, inducing **local secretory IgA antibodies**. This provides intestinal immunity, which prevents the wild virus from multiplying in the gut and breaking the chain of transmission—a feature the IPV lacks. **High-Yield Clinical Pearls for NEET-PG:** * **AFP Surveillance Criteria:** 1) Report all cases of AFP in children <15 years. 2) Collect two "adequate" stool samples within 14 days of onset of paralysis, 24 hours apart. * **VAPP vs. VDPV:** Vaccine-Associated Paralytic Polio (VAPP) occurs in the vaccine recipient; Vaccine-Derived Poliovirus (VDPV) occurs due to the circulation of the mutated virus in the community. * **Switch:** India switched from Trivalent OPV to Bivalent OPV (Types 1 & 3) in 2016 because Type 2 wild virus was eradicated.

Question 403: Xpert MTB/RIF is used in the diagnosis of which disease?

A. Tuberculosis (Correct Answer)
B. Malaria
C. HIV/AIDS
D. Hepatitis C Virus (HCV)

Explanation: **Explanation:** **Xpert MTB/RIF** is a revolutionary molecular diagnostic test for **Tuberculosis (TB)**. It utilizes a cartridge-based nucleic acid amplification test (CBNAAT) platform to simultaneously detect the DNA of *Mycobacterium tuberculosis* complex and mutations associated with **Rifampicin resistance** (a proxy for multidrug-resistant TB). It is the preferred initial diagnostic test according to the National Tuberculosis Elimination Program (NTEP) due to its high sensitivity and rapid results (within 2 hours). **Analysis of Incorrect Options:** * **B. Malaria:** Diagnosis primarily relies on peripheral blood smears (Gold Standard) or Rapid Diagnostic Tests (RDTs) detecting parasite antigens like HRP-2 or LDH. * **C. HIV/AIDS:** Initial screening is done via ELISA (p24 antigen and antibodies), while confirmation and monitoring involve Western Blot or Viral Load (RT-PCR). * **D. Hepatitis C:** Diagnosis involves anti-HCV antibody screening followed by HCV RNA quantification using PCR to confirm active infection. **High-Yield Clinical Pearls for NEET-PG:** * **Sample:** Sputum is most common, but it can also be used on gastric aspirate, tissue biopsy, and CSF (Extrapulmonary TB). * **Sensitivity:** It is significantly more sensitive than sputum smear microscopy, especially in smear-negative and HIV-associated TB. * **Rifampicin Resistance:** If Xpert MTB/RIF detects resistance, the patient is managed as **MDR-TB** until further drug susceptibility testing (DST) is performed. * **Truenat:** An indigenous Indian chip-based real-time PCR test similar to CBNAAT, also used under NTEP for TB diagnosis at the primary health care level.

Question 404: Which vaccine strain needs to be changed every year?

A. Measles
B. Mumps
C. Influenza (Correct Answer)
D. Polio

Explanation: **Explanation:** The correct answer is **Influenza** because of the unique genetic characteristics of the Influenza virus, specifically **Antigenic Drift**. **1. Why Influenza?** Influenza viruses (Type A and B) undergo frequent point mutations in the genes coding for surface glycoproteins, **Hemagglutinin (HA)** and **Neuraminidase (NA)**. This process, known as *Antigenic Drift*, results in new virus strains that can evade the immune system of individuals previously infected or vaccinated. Consequently, the World Health Organization (WHO) monitors global circulation and updates the vaccine composition annually (Northern and Southern Hemisphere strains) to ensure a close antigenic match. **2. Why the other options are incorrect:** * **Measles & Mumps:** These are caused by viruses that are antigenically stable. The surface antigens do not undergo significant mutations over time, meaning the immunity conferred by the standard MMR vaccine remains effective for decades. * **Polio:** The three serotypes of Poliovirus (1, 2, and 3) are stable. While the world has switched from Trivalent to Bivalent OPV (removing Type 2), the strains themselves do not require annual updates. **High-Yield Clinical Pearls for NEET-PG:** * **Antigenic Drift:** Seen in both Influenza A and B; leads to **epidemics**. * **Antigenic Shift:** Seen **only in Influenza A**; involves genetic reassortment leading to a major change (new subtype); leads to **pandemics**. * **Vaccine Timing:** In India, it is ideally administered before the monsoon season. * **Composition:** Most modern vaccines are **Quadrivalent** (2 strains of Influenza A and 2 lineages of Influenza B).

Question 405: Which body fluid has the maximum HIV load?

A. Urine
B. Blood (Correct Answer)
C. Breast milk
D. Saliva

Explanation: **Explanation:** The concentration of HIV (viral load) varies significantly across different body fluids, which directly determines the risk of transmission. **1. Why Blood is the Correct Answer:** Blood contains the highest concentration of HIV virions. This is because HIV primarily infects and replicates within CD4+ T-lymphocytes and macrophages, which are abundant in the bloodstream. Consequently, percutaneous exposure to infected blood (e.g., needle-stick injuries or blood transfusions) carries the highest risk of transmission compared to other body fluids. **2. Analysis of Incorrect Options:** * **Breast Milk:** While breast milk contains enough virus to facilitate mother-to-child transmission (MTCT), the viral concentration is significantly lower than that found in blood or semen. * **Urine & Saliva:** These are considered "non-infectious" fluids in the context of HIV (unless visibly contaminated with blood). They contain negligible amounts of the virus or possess inhibitory enzymes (like secretory leukocyte protease inhibitor in saliva) that neutralize the virus, making transmission via these routes virtually impossible. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hierarchy of Viral Load:** Blood > Semen > Vaginal Secretions > Breast Milk. * **Transmission Risk:** The highest risk of transmission per single act is through **Blood Transfusion** (approx. 90-95%), followed by Receptive Anal Intercourse. * **Window Period:** The time between infection and the appearance of detectable antibodies (usually 2-8 weeks). The **p24 antigen** is the earliest marker detectable in the blood after the eclipse phase. * **Post-Exposure Prophylaxis (PEP):** Should ideally be started within 2 hours, but no later than 72 hours, and continued for 28 days.

Question 406: World Anti-TB Day is observed on which date?

A. 30th January
B. 4th February
C. 24th March (Correct Answer)
D. 1st December

Explanation: **Explanation:** **Correct Option: C (24th March)** World Tuberculosis (TB) Day is observed annually on **March 24th**. This date commemorates the day in **1882** when **Dr. Robert Koch** announced his discovery of *Mycobacterium tuberculosis*, the bacillus that causes tuberculosis. This discovery opened the way toward diagnosing and curing the disease. The goal of this day is to raise public awareness about the devastating health, social, and economic consequences of TB and to step up efforts to end the global TB epidemic. **Analysis of Incorrect Options:** * **A. 30th January:** This is **World Leprosy Day** (specifically in India, coinciding with Mahatma Gandhi’s martyrdom). Globally, it is observed on the last Sunday of January. It is also observed as **Anti-Leprosy Day**. * **B. 4th February:** This is **World Cancer Day**, organized by the Union for International Cancer Control (UICC) to promote awareness and education regarding cancer prevention. * **D. 1st December:** This is **World AIDS Day**, dedicated to raising awareness of the AIDS pandemic caused by the spread of HIV infection. **High-Yield Facts for NEET-PG:** * **NTEP:** The Revised National TB Control Programme (RNTCP) was renamed the **National Tuberculosis Elimination Program (NTEP)** in 2020. * **Target:** India aims to eliminate TB by **2025**, five years ahead of the global Sustainable Development Goal (SDG) target of 2030. * **Nikshay Poshan Yojana:** A direct benefit transfer (DBT) scheme providing ₹500/month for nutritional support to TB patients. * **TrueNat/CBNAAT:** These are the preferred first-line molecular diagnostic tests under current guidelines to detect drug resistance early.

Question 407: Which of the following is not a barrier method?

A. Centchroman (Correct Answer)
B. Today
C. Barrier contraceptive
D. None

Explanation: **Explanation:** The correct answer is **Centchroman** because it is a **hormonal (non-steroidal) oral contraceptive pill**, not a barrier method. **1. Why Centchroman is the correct answer:** Centchroman (commercially known as **Chhaya** or **Saheli**) is a Selective Estrogen Receptor Modulator (SERM). It works by preventing the implantation of the blastocyst by altering the endometrial receptivity. It is unique because it is the world’s first non-steroidal oral contraceptive, developed by CDRI, Lucknow. Since it acts systemically via hormonal receptors rather than providing a physical or chemical block at the cervix, it is not a barrier method. **2. Analysis of incorrect options:** * **Today:** This is a brand name for a **vaginal contraceptive sponge**. It acts as a barrier method by providing a physical block to the cervix and a chemical block via the spermicide (Nonoxynol-9) it contains. * **Barrier contraceptive:** This is a broad category that includes physical devices (condoms, diaphragms) and chemical agents (foams, jellies) designed to prevent sperm from entering the uterus. **High-Yield Clinical Pearls for NEET-PG:** * **Centchroman Dosage:** Under the National Family Planning Program (Antara program), it is taken **twice a week for the first 3 months**, followed by **once a week** thereafter. * **Ideal Candidate:** It is the contraceptive of choice for breastfeeding mothers (does not affect lactation) and women who want to avoid steroidal side effects like weight gain or nausea. * **Pearl:** The most effective barrier method for preventing STIs/HIV is the male condom. * **Spermicides:** Most common chemical barrier used is **Nonoxynol-9**, which acts by disrupting the sperm cell membrane.

Question 408: Which of the following statements about meningococcal meningitis is FALSE?

A. The source of infection is mainly clinical cases. (Correct Answer)
B. The disease is more common in dry and cold months of the year.
C. Chemoprophylaxis of close contacts of cases is recommended.
D. The vaccine is not effective in children below 2 years of age.

Explanation: **Explanation:** **1. Why Option A is the correct (False) statement:** In Meningococcal Meningitis (caused by *Neisseria meningitidis*), the primary source of infection is **carriers**, not clinical cases. The ratio of carriers to cases is estimated to be around **100:1**. Carriers harbor the bacteria in their nasopharynx and are responsible for the continued transmission and maintenance of the infection in the community. Clinical cases represent only the "tip of the iceberg." **2. Analysis of other options:** * **Option B:** This is **True**. The disease shows a distinct seasonal pattern, with a higher incidence during **dry and cold months** (winter and spring). Low humidity and dust facilitate the colonization of the nasopharynx. * **Option C:** This is **True**. Chemoprophylaxis is mandatory for **close contacts** (household members, daycare contacts) to eliminate the carrier state. **Rifampicin** is the drug of choice; alternatives include Ciprofloxacin or Ceftriaxone. * **Option D:** This is **True** for the older **Polysaccharide vaccines** (MPSV4), which are poorly immunogenic in children under 2 years due to an immature T-cell independent immune response. However, newer Conjugate vaccines (MCV4) are effective in infants. **High-Yield Clinical Pearls for NEET-PG:** * **Reservoir:** Exclusively human (no animal reservoir). * **Portal of Entry:** Nasopharynx (via droplet infection). * **Incubation Period:** 3 to 4 days (range 2–10 days). * **Drug of Choice for Treatment:** Ceftriaxone or Penicillin G. * **Chemoprophylaxis:** Rifampicin (5-10 mg/kg) for 2 days. * **Epidemic Indicator:** An attack rate of >15 cases per 100,000 per week for two consecutive weeks indicates an outbreak.

Question 409: What is true about the varicella vaccine?

A. It is poorly immunogenic.
B. Its immunity lasts for 4-6 months.
C. Salicylates should be avoided for 4-6 weeks after vaccination. (Correct Answer)
D. It is given to children less than 12 months of age who do not have chickenpox.

Explanation: **Explanation:** The correct answer is **C: Salicylates should be avoided for 4-6 weeks after vaccination.** **Why Option C is Correct:** The varicella vaccine is a **live-attenuated vaccine** (Oka strain). There is a theoretical risk of developing **Reye’s Syndrome** if salicylates (aspirin) are administered following vaccination with a live varicella virus. Reye’s Syndrome is a rare but fatal condition characterized by acute encephalopathy and fatty liver degeneration, typically occurring when aspirin is used during wild-type influenza or varicella infections. To mitigate this risk, it is recommended to avoid salicylates for at least 6 weeks after receiving the vaccine. **Analysis of Incorrect Options:** * **Option A:** The vaccine is **highly immunogenic**. A single dose produces seroconversion in approximately 95% of children. * **Option B:** The immunity is long-lasting. It provides protection for at least **10–20 years**, not just 4–6 months. * **Option C:** The vaccine is generally **not recommended for children less than 12 months of age** due to the presence of maternal antibodies which can interfere with the immune response. The first dose is typically given at 12–15 months. **High-Yield Clinical Pearls for NEET-PG:** * **Strain:** Oka strain (Live attenuated). * **Schedule:** 2 doses. 1st dose at 12–15 months; 2nd dose at 4–6 years. * **Post-exposure Prophylaxis:** Effective if given within **3–5 days** of exposure. * **Contraindications:** Pregnancy (avoid pregnancy for 1 month post-vaccination), immunocompromised states, and neomycin allergy. * **Breakthrough Varicella:** Occurs in vaccinated individuals; it is usually mild, with fewer than 50 lesions and no fever.

Question 410: What is the prevalence of HIV in Andhra Pradesh and Tamil Nadu?

A. Low
B. Moderate
C. High (Correct Answer)
D. Low moderate

Explanation: **Explanation:** In the context of India’s National AIDS Control Programme (NACP), states are categorized based on their HIV prevalence. Andhra Pradesh and Tamil Nadu are historically classified as **High Prevalence** states. This classification is primarily based on sentinel surveillance data showing an HIV prevalence of >5% among High-Risk Groups (HRGs) and >1% among antenatal clinic (ANC) attendees. **Why "High" is correct:** Andhra Pradesh and Tamil Nadu, along with Maharashtra, Karnataka, Manipur, and Nagaland, have consistently reported high HIV burdens. This is attributed to high-density migration, large populations of female sex workers (FSWs), and high rates of sexually transmitted infections (STIs) in these regions. Although recent NACP interventions have successfully stabilized or reduced the incidence, they remain in the high-prevalence category for epidemiological tracking. **Why other options are incorrect:** * **Low/Moderate:** These categories apply to states where ANC prevalence is <1% and HRG prevalence is lower. States like Kerala or those in Central India often fall into these categories. * **Low moderate:** This is not a standard epidemiological classification used by NACO (National AIDS Control Organisation). **High-Yield Pearls for NEET-PG:** * **Most common mode of transmission in India:** Heterosexual (approx. 85-88%). * **State with highest prevalence (Adults):** Mizoram (followed by Nagaland and Manipur). * **Sentinel Surveillance:** The primary tool for monitoring HIV trends in India. * **Targeted Intervention (TI):** The core strategy for HRGs (FSWs, MSM, IDUs) to prevent the transition from a concentrated to a generalized epidemic.

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