Non-Communicable Diseases — MCQs

Non-Communicable Diseases Indian Medical PG Practice Questions and MCQs

Question 61: Rabies can be transmitted by all of the following routes except?

A. Aerosol
B. Bites
C. Ingestion (Correct Answer)
D. Licks

Explanation: ### Explanation **Correct Option: C (Ingestion)** **Reasoning:** Rabies is caused by the **Lyssavirus Type 1** (a neurotropic RNA virus). The virus is highly fragile and is inactivated by gastric acid (low pH) and digestive enzymes. Therefore, the ingestion of milk or meat from a rabid animal does not transmit the disease, as the virus cannot survive the gastrointestinal environment to reach the nervous system. **Analysis of Other Options:** * **Bites (Option B):** This is the most common route (over 99% of human cases). The virus is present in the saliva of the rabid animal and is inoculated into the host via a bite. * **Licks (Option D):** Transmission occurs if the saliva of a rabid animal comes into contact with **pre-existing scratches, open wounds, or intact mucous membranes** (eyes, mouth). This is classified as a Category II or III exposure depending on the severity. * **Aerosol (Option A):** Though rare, transmission can occur via inhalation of virus-laden aerosols. This has been documented in specific laboratory accidents and among individuals exploring caves heavily populated by infected bats (guano-rich environments). **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Typically 1–3 months (Range: <7 days to >1 year). It depends on the distance of the bite from the CNS and the viral load. * **Organ Transplant:** Rabies can be transmitted via **corneal or solid organ transplants** from infected donors. * **Diagnosis:** The presence of **Negri bodies** (intracytoplasmic inclusions) in the hippocampus or cerebellum is pathognomonic (post-mortem). * **Category III Exposure:** Includes single/multiple transdermal bites, licks on broken skin, or contamination of mucous membranes with saliva. This requires both **Vaccine and Rabies Immunoglobulin (RIG)**.

Question 62: Which of the following diseases is associated with a chronic carrier state?

A. Measles
B. Whooping cough
C. Typhoid (Correct Answer)
D. Influenza

Explanation: **Explanation:** The concept of a **carrier state** refers to an individual who harbors a specific infectious agent without showing clinical signs of the disease but serves as a potential source of infection to others. **Why Typhoid is Correct:** *Salmonella typhi* is notorious for establishing a **chronic carrier state** (defined as excreting the bacilli for more than one year). The bacteria typically persist in the **gallbladder** (biliary carriers) or, less commonly, in the urinary tract. This state is more frequent in females and those with pre-existing gallstones. The classic historical example is "Typhoid Mary." **Why Other Options are Incorrect:** * **Measles:** This is an acute viral infection characterized by high infectivity during the prodromal stage. It does **not** have a carrier state; an individual is either infected and symptomatic or immune. * **Whooping Cough (Pertussis):** There is no known chronic carrier state for *Bordetella pertussis*. Transmission occurs via respiratory droplets from active cases. * **Influenza:** This is an acute respiratory viral infection. While subclinical infections occur, there is no chronic carrier state; the virus is cleared rapidly by the immune system or leads to acute illness. **High-Yield NEET-PG Pearls:** 1. **Incubatory Carrier:** Sheds infectious agent during the incubation period (e.g., Measles, Mumps, Polio). 2. **Convalescent Carrier:** Sheds agent during recovery (e.g., Typhoid, Dysentery). 3. **Chronic Carrier:** Sheds agent for indefinite periods (e.g., Typhoid, Hepatitis B, HIV). 4. **Typhoid Management:** The drug of choice for clearing the typhoid carrier state is **Ampicillin** (often combined with Probenecid) or **Ciprofloxacin** for 4–6 weeks. Cholecystectomy may be required if gallstones are present.

Question 63: Which of the following is an AIDS-defining criterion as per WHO?

A. Generalized lymphadenopathy (Correct Answer)
B. Fever, weight loss, and fatigue
C. Pneumocystis carinii Pneumonia
D. Mycobacterium avium infection

Explanation: ### Explanation **Correct Option: A. Generalized lymphadenopathy** The World Health Organization (WHO) uses a clinical staging system for HIV/AIDS to guide management in resource-limited settings. **Generalized lymphadenopathy** (specifically Persistent Generalized Lymphadenopathy or PGL) is categorized under **WHO Clinical Stage 1**. While Stage 4 conditions are typically referred to as "AIDS-defining illnesses" in clinical practice, the WHO classification considers specific clinical findings across all stages as criteria for defining the progression of HIV infection. In the context of this specific question format (often seen in older NEET-PG/AIIMS patterns), PGL is recognized as a primary clinical criterion for the initial staging of the disease. **Analysis of Incorrect Options:** * **B. Fever, weight loss, and fatigue:** These are non-specific constitutional symptoms. While weight loss (>10%) is part of Stage 3 (Moderate) and Stage 4 (Wasting syndrome), these symptoms alone are not specific enough to be the primary defining criterion without meeting specific duration or severity thresholds. * **C & D. Pneumocystis jirovecii (formerly carinii) and Mycobacterium avium:** These are **Stage 4** conditions (Opportunistic Infections). While they are "AIDS-defining" in the CDC classification, in the context of WHO clinical criteria, they represent the most advanced stage of the disease rather than the baseline clinical criterion used for early identification/staging. **High-Yield Clinical Pearls for NEET-PG:** * **WHO Stage 1:** Asymptomatic or Persistent Generalized Lymphadenopathy (PGL). * **WHO Stage 2:** Minor mucocutaneous manifestations (e.g., Seborrheic dermatitis, fungal nail infections, recurrent oral ulcerations). * **WHO Stage 3:** Conditions like unexplained chronic diarrhea (>1 month), pulmonary tuberculosis, and severe bacterial infections. * **WHO Stage 4:** Definitive AIDS-defining illnesses including Extrapulmonary TB, Esophageal Candidiasis, Kaposi Sarcoma, and Toxoplasmosis. * **CD4 Count:** Regardless of clinical stage, a CD4 count **<200 cells/mm³** is the laboratory definition of AIDS.

Question 64: The Cheopis Index is used for which disease?

A. Rabies
B. Plague (Correct Answer)
C. Yellow fever
D. Leishmaniasis

Explanation: **Explanation:** The **Cheopis Index** is a specific entomological parameter used in the surveillance and control of **Plague**. It refers to the average number of *Xenopsylla cheopis* (the Oriental rat flea) found per rat. Since *X. cheopis* is the most efficient vector for transmitting *Yersinia pestis* from rats to humans, a high index indicates an increased risk of a plague outbreak. An index greater than **1.0** is considered the critical threshold for potential epidemic spread. **Analysis of Options:** * **Plague (Correct):** In addition to the Cheopis Index, other indices used include the *Specific Flea Index* and the *Percentage Flea Index*. Monitoring these helps in timing insecticide sprays to prevent human transmission. * **Rabies:** Surveillance focuses on animal bite statistics and post-exposure prophylaxis (PEP) coverage, not flea indices. It is a viral zoonosis transmitted via saliva. * **Yellow Fever:** The relevant indices here are the **Aedes indices** (e.g., House Index, Container Index, and Breteau Index), as the disease is transmitted by *Aedes aegypti* mosquitoes. * **Leishmaniasis (Kala-azar):** This is transmitted by the **Sandfly** (*Phlebotomus argentipes*). Surveillance involves monitoring the sandfly density in human dwellings. **High-Yield Clinical Pearls for NEET-PG:** * **Vector of Plague:** *Xenopsylla cheopis* (most common/efficient) and *Xenopsylla astia*. * **Critical Cheopis Index:** >1 (indicates immediate danger of an outbreak). * **Drug of Choice (Treatment):** Streptomycin (Gentamicin is an alternative). * **Drug of Choice (Chemoprophylaxis):** Doxycycline or Tetracycline. * **Quarantine Period:** 6 days for international travelers coming from endemic zones.

Question 65: Which vaccine is contraindicated in pregnancy?

A. Hepatitis A
B. Varicella (Correct Answer)
C. Rabies
D. Hepatitis B

Explanation: **Explanation:** The core principle in obstetric immunization is that **live attenuated vaccines** are generally **contraindicated** during pregnancy. This is due to the theoretical risk of the vaccine virus crossing the placenta and causing fetal infection or congenital anomalies. **1. Why Varicella is the Correct Answer:** The Varicella vaccine contains a live attenuated virus (Oka strain). Administration during pregnancy poses a risk of **Congenital Varicella Syndrome**, characterized by limb hypoplasia, skin scarring, and microcephaly. Women are advised to avoid pregnancy for at least 28 days (1 month) after receiving this vaccine. **2. Analysis of Incorrect Options:** * **Hepatitis A & B:** These are **inactivated (killed) or recombinant vaccines**. They are not contraindicated if the risk of infection is high. Hepatitis B vaccination is specifically indicated for pregnant women at risk of occupational exposure or those with infected partners. * **Rabies:** This is a **post-exposure prophylaxis (PEP)** vaccine. Since rabies is 100% fatal, the vaccine is **never contraindicated** in pregnancy if a category II or III bite occurs. Life-saving interventions always take precedence. **3. NEET-PG High-Yield Pearls:** * **Absolute Contraindications in Pregnancy:** Live vaccines like **MMR (Measles, Mumps, Rubella)**, **Varicella**, **Yellow Fever**, and **BCG**. * **The Exception:** Yellow Fever vaccine may be given if travel to an endemic area is unavoidable and the risk of disease outweighs the risk of vaccination. * **Safest/Recommended:** **Tetanus, Diphtheria, and acellular Pertussis (Tdap)** is recommended in every pregnancy (ideally between 27–36 weeks) to provide passive immunity to the neonate. * **Influenza:** The **inactivated** injectable flu vaccine is safe and recommended in any trimester; however, the **Live Attenuated Influenza Vaccine (LAIV/Nasal spray)** is contraindicated.

Question 66: Which of the following statements about whooping cough is false?

A. It commonly affects children under 1 year of age.
B. Primary cases are the most important source of infection.
C. Asymptomatic carriers are the most important source of infection. (Correct Answer)
D. The secondary attack rate is high.

Explanation: **Explanation:** The correct answer is **C**. In Pertussis (Whooping Cough), **asymptomatic carriers do not play a significant role** in the transmission of the disease. The primary source of infection is a clinical case, particularly during the early catarrhal stage when the bacterial load is highest. **Why Option C is False:** Unlike diseases like Diphtheria or Typhoid, Pertussis is characterized by the absence of a chronic carrier state. While mild or atypical cases occur in immunized individuals, the "source of infection" is almost always an **active case** (primary case). **Analysis of Other Options:** * **Option A:** Pertussis predominantly affects infants and young children. In fact, the highest morbidity and mortality are seen in **children under 1 year of age**, as they are often too young to have completed the primary vaccination series. * **Option B:** Clinical cases (primary cases) are the most infectious. The period of communicability is highest during the **catarrhal stage** (first 1-2 weeks) before the characteristic "whoop" begins. * **Option D:** Pertussis is highly contagious. The **Secondary Attack Rate (SAR)** in susceptible household contacts is very high, often cited between **80-90%**. **High-Yield NEET-PG Pearls:** * **Causative Agent:** *Bordetella pertussis* (Gram-negative coccobacillus). * **Incubation Period:** Usually 7–10 days (Range: 6–20 days). * **Drug of Choice:** **Erythromycin** (or other Macrolides like Azithromycin) for 7–14 days. It reduces communicability but has limited clinical benefit if started in the paroxysmal stage. * **Vaccine:** Part of the DPT/Pentavalent vaccine. The **acellular (aP)** vaccine has fewer side effects than the whole-cell (wP) vaccine. * **Diagnosis:** Culture on **Regen-Lowe** or **Bordet-Gengou medium** is the gold standard, though PCR is now preferred for speed.

Question 67: Four split skin smears from a single patient show the following results: Two samples contain 10 bacilli per 100 high power fields (hpf), and two samples contain over 1000 bacilli per average fields. What is the bacteriological index?

A. 3.5 (Correct Answer)
B. 4.5
C. 5.5
D. 6.5

Explanation: To solve this question, we must first determine the **Bacteriological Index (BI)** for each individual smear using Ridley’s Logarithmic Scale and then calculate the average. ### 1. Understanding the Calculation The BI is calculated based on the density of *M. leprae* in skin smears: * **1+**: 1–10 bacilli per 100 high power fields (hpf) * **2+**: 1–10 bacilli per 10 hpf * **3+**: 1–10 bacilli per average field * **4+**: 10–100 bacilli per average field * **5+**: 100–1000 bacilli per average field * **6+**: >1000 bacilli per average field **Step-by-step calculation for this patient:** * **Smears 1 & 2:** 10 bacilli/100 hpf = **1+** (each) * **Smears 3 & 4:** >1000 bacilli/avg field = **6+** (each) * **Total BI Sum:** 1 + 1 + 6 + 6 = **14** * **Average BI:** 14 ÷ 4 (total sites) = **3.5** ### 2. Why Other Options are Incorrect * **B (4.5), C (5.5), D (6.5):** These values result from incorrect application of the Ridley scale or mathematical errors in averaging. For instance, a BI of 6.5 is impossible as the maximum scale value is 6. ### 3. High-Yield Clinical Pearls for NEET-PG * **Sites for Smear:** Usually taken from 4–6 sites (e.g., both earlobes, two lesions, and the nasal mucosa). * **BI vs. MI:** While **BI** measures the total bacterial load (living and dead), the **Morphological Index (MI)** measures the percentage of solid-staining (viable) bacilli. * **WHO Classification:** * **Paucibacillary (PB):** BI < 2 at all sites. * **Multibacillary (MB):** BI ≥ 2 at any site (though clinically, any positive smear is now treated as MB). * **Treatment Duration:** MB Leprosy requires 12 months of MDT (Rifampicin, Dapsone, Clofazimine), while PB requires 6 months (Rifampicin, Dapsone).

Question 68: What is true about the epidemiology of influenza?

A. Asymptomatic cases are seen rarely.
B. The incubation period is 10-12 hours.
C. Pandemics are rare.
D. Extra-human reservoirs are seen. (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Extra-human reservoirs are seen.** Influenza viruses, particularly **Influenza A**, exhibit a vast extra-human reservoir. They infect a wide range of animals and birds (e.g., ducks, chickens, pigs, horses, and seals). These reservoirs are crucial for the emergence of new subtypes through **antigenic shift** (genetic reassortment), which can lead to pandemics. In contrast, Influenza B and C are almost exclusively human pathogens. **Analysis of Incorrect Options:** * **A. Asymptomatic cases are seen rarely:** This is incorrect. Subclinical or asymptomatic infections are quite common in influenza and play a significant role in the rapid spread of the virus within a community. * **B. The incubation period is 10-12 hours:** This is incorrect. The incubation period for influenza is typically **1 to 4 days**, with an average of **2 days**. It is short, but not as brief as 10 hours. * **C. Pandemics are rare:** While pandemics do not occur every year, they are a characteristic feature of Influenza A. Major pandemics have occurred at intervals (e.g., 1918, 1957, 1968, and 2009). The statement is misleading because the *potential* for pandemics is a defining epidemiological trait of the virus. **High-Yield NEET-PG Pearls:** * **Antigenic Shift:** Major abrupt change (reassortment) in Influenza A only; leads to **Pandemics**. * **Antigenic Drift:** Minor point mutations in Influenza A and B; leads to **Epidemics** and necessitates annual vaccine updates. * **Period of Communicability:** Adults are infectious from 1 day before to 5 days after the onset of symptoms. * **Drug of Choice:** Oseltamivir (Neuraminidase inhibitor) is the preferred treatment for both seasonal and avian flu. * **Vaccine:** The most common is the **Inactivated (killed)** vaccine given IM; the Live Attenuated Influenza Vaccine (LAIV) is administered intranasally.

Question 69: All of the following are zoonotic infections EXCEPT?

A. Plague
B. Japanese Encephalitis
C. HIV (Correct Answer)
D. Tuberculosis

Explanation: ### Explanation **Concept:** A **zoonosis** is defined by the WHO as an infection or infectious disease transmissible under natural conditions from vertebrate animals to humans. The key to this question lies in distinguishing between diseases that maintain an animal reservoir (zoonoses) and those that are exclusively human-to-human pathogens. **Why HIV is the Correct Answer:** While the ancestors of **HIV** (SIV) originated in primates, HIV itself is classified as a **human-specific infection**. It is transmitted exclusively between humans via blood, sexual contact, or vertical transmission. It does not have a contemporary animal reservoir that naturally infects humans in the current epidemiological cycle. **Analysis of Incorrect Options:** * **Plague (Option A):** A classic zoonosis caused by *Yersinia pestis*. It is primarily a disease of **rodents** (wild and domestic), transmitted to humans via the bite of an infected rat flea (*Xenopsylla cheopis*). * **Japanese Encephalitis (Option B):** An obligate zoonosis. The virus is maintained in an enzootic cycle involving **pigs** (amplifier hosts) and **water birds** (ardied birds), transmitted to humans by *Culex* mosquitoes. * **Tuberculosis (Option D):** While *M. tuberculosis* is primarily human, **Bovine Tuberculosis** (*Mycobacterium bovis*) is a major zoonotic pathogen transmitted to humans via unpasteurized milk from infected cattle. Therefore, TB is categorized under zoonotic infections in public health classifications. **High-Yield Clinical Pearls for NEET-PG:** * **Anthropozoonoses:** Diseases transmitted from animals to humans (e.g., Rabies, Leptospirosis). * **Zooanthroponoses:** Diseases transmitted from humans to animals (e.g., Human TB to cattle). * **Cyclozoonosis:** Requires more than one vertebrate host (e.g., Echinococcosis, Taeniasis). * **Metazoonosis:** Requires both a vertebrate host and an invertebrate vector (e.g., Plague, JE). * **Saprozoonosis:** Requires a non-animal environmental reservoir like soil (e.g., Histoplasmosis).

Question 70: After vaccination against Japanese encephalitis, when does immunity develop?

A. 30 days (Correct Answer)
B. 7 days
C. 10 days
D. 21 days

Explanation: **Explanation:** The correct answer is **30 days (Option A)**. In the context of Japanese Encephalitis (JE) vaccination, particularly with the live attenuated SA 14-14-2 vaccine (which is the strain used in India's Universal Immunization Programme), it takes approximately one month for the body to mount a protective immune response. **Why 30 days is correct:** Immunity following JE vaccination is not immediate. Studies on seroconversion indicate that while some antibodies appear earlier, a robust, protective level of neutralizing antibodies (titer ≥1:10) typically develops by **4 weeks (28-30 days)** post-vaccination. This timeframe is crucial for public health planning during outbreaks or before traveling to endemic areas. **Analysis of Incorrect Options:** * **7 days (Option B):** This is too early for a primary immune response to reach protective thresholds. * **10 days (Option C):** While some IgM may be detectable, the protective IgG response is still maturing. * **21 days (Option D):** Although the immune response is well underway, the standard clinical and textbook consensus for full immunity is 30 days. **High-Yield Facts for NEET-PG:** * **Vaccine Strain:** The most common vaccine used in India is the **SA 14-14-2** (Live Attenuated, Chinese origin). * **UIP Schedule:** Two doses are given under the Universal Immunization Programme—the 1st dose at **9 months** (with Measles/MR) and the 2nd dose at **16–24 months** (with DPT booster). * **Route:** Subcutaneous (0.5 ml). * **Vector:** Primarily transmitted by the **Culex tritaeniorhynchus** mosquito, which breeds in stagnant water like rice fields. * **Amplifier Host:** The **Pig** is the most important amplifier host (the mosquito-pig-mosquito cycle). Humans are "dead-end" hosts.

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