Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 91: After initiation of DOTS therapy for category-I, when is the first sputum examination done?

A. 1 month of treatment
B. 2 months of treatment (Correct Answer)
C. 4 months of treatment
D. 6 months of treatment

Explanation: **Explanation:** Under the National Tuberculosis Elimination Program (NTEP), the monitoring of treatment response for **Category-I (New cases)** is primarily done through follow-up sputum smear microscopy. **Why Option B is correct:** Category-I treatment consists of an **Intensive Phase (IP)** of 2 months (HRZE) followed by a **Continuation Phase (CP)** of 4 months (HRE). The first follow-up sputum examination is scheduled at the **end of the Intensive Phase (2 months)**. This is a critical milestone to assess "sputum conversion" (from positive to negative), which indicates the effectiveness of the treatment and a reduction in the patient's infectivity. **Why other options are incorrect:** * **Option A (1 month):** This is too early to assess microbiological conversion for standard pulmonary TB. * **Option C (4 months):** Under previous guidelines, a smear was done at 4 months, but current protocols emphasize testing at the end of IP (2 months) and at the end of treatment (6 months). * **Option D (6 months):** This is the timing for the **final** sputum examination to declare the patient "Cured." **High-Yield Clinical Pearls for NEET-PG:** * **Follow-up Schedule:** For New cases, sputum is checked at **2 months** (end of IP) and **6 months** (end of CP). * **If Smear is Positive at 2 Months:** In the current NTEP algorithm, if the 2-month smear is positive, the patient is still transitioned to the Continuation Phase, but a **NAAT (CBNAAT/Truenat)** must be performed to rule out Drug-Resistant TB (DR-TB). * **Definition of "Cured":** A patient who was initially smear-positive, completed treatment, and had a negative smear at the end of treatment (6 months) plus at least one previous negative result.

Question 92: Which of the following are not sexually transmitted infections?

A. Hepatitis A virus (HAV) and Varicella zoster virus (VZV) (Correct Answer)
B. Human Immunodeficiency Virus (HIV)
C. Hepatitis A virus (HAV) and Human T-lymphotropic virus type I (HTLV-I)
D. Hepatitis A virus (HAV) and Human Papillomavirus (HPV)

Explanation: **Explanation:** The core concept of this question lies in distinguishing between pathogens primarily transmitted through sexual contact and those transmitted via respiratory or feco-oral routes. **Why Option A is Correct:** * **Hepatitis A Virus (HAV):** It is primarily transmitted via the **feco-oral route** (contaminated food/water). While sexual transmission can occur among men who have sex with men (MSM) due to oral-anal contact, it is not classified as a classic Sexually Transmitted Infection (STI). * **Varicella Zoster Virus (VZV):** This virus causes Chickenpox and Herpes Zoster. It is transmitted via **respiratory droplets** or direct contact with vesicle fluid. It is never classified as an STI. **Analysis of Incorrect Options:** * **Option B (HIV):** HIV is a classic STI, transmitted through blood, semen, and vaginal fluids. * **Option C (HTLV-I):** This retrovirus is transmitted through sexual contact, blood transfusion, and breastfeeding. It is a recognized STI. * **Option D (HPV):** Human Papillomavirus is one of the most common STIs globally, leading to genital warts and cervical cancer. **NEET-PG High-Yield Pearls:** * **Hepatitis & Sex:** Hepatitis B, C, and D are considered STIs (HBV being the most sexually transmissible). Hepatitis A and E are feco-oral. * **Ulcerative vs. Non-Ulcerative STIs:** Remember that Syphilis, Chancroid, and LGV are ulcerative, while Gonorrhea and Chlamydia are typically non-ulcerative. * **VZV Transmission:** VZV is highly contagious via the respiratory route *before* the rash appears. Once lesions crust over, they are no longer infectious.

Question 93: What is the recommended prophylactic treatment for close contacts of meningococcal meningitis?

A. Rifampicin (Correct Answer)
B. Erythromycin
C. Penicillin
D. Cephalosporins

Explanation: **Explanation:** **1. Why Rifampicin is Correct:** Rifampicin is the drug of choice for the chemoprophylaxis of meningococcal meningitis. The goal of prophylaxis is to eradicate the nasopharyngeal carriage of *Neisseria meningitidis* in close contacts (e.g., household members, daycare contacts, or healthcare workers exposed to respiratory secretions). Rifampicin achieves high concentrations in salivary and respiratory secretions, effectively eliminating the carrier state and preventing secondary cases. The standard adult dose is 600 mg twice daily for 2 days. **2. Why the Other Options are Incorrect:** * **Erythromycin:** While a macrolide, it is not the standard of care for meningococcal prophylaxis as it is less effective at eradicating the nasopharyngeal carrier state compared to Rifampicin. * **Penicillin:** Although Penicillin G is the treatment of choice for the *active disease* (meningococcemia/meningitis), it does not reliably eliminate the nasopharyngeal carriage and therefore is not used for prophylaxis. * **Cephalosporins:** While 3rd generation cephalosporins (like Ceftriaxone) are used for treatment and can be used as an alternative for prophylaxis (via a single IM injection), they are not the primary first-line oral recommendation over Rifampicin in standard guidelines. **3. High-Yield Clinical Pearls for NEET-PG:** * **Alternative Prophylaxis:** If Rifampicin is contraindicated (e.g., pregnancy), **Ciprofloxacin** (500 mg single dose) or **Ceftriaxone** (250 mg IM single dose) are the preferred alternatives. * **Timing:** Prophylaxis should ideally be administered within 24 hours of identifying the index case. * **Side Effect Note:** Warn patients that Rifampicin may turn urine, sweat, and tears orange/red. * **Vaccination:** Chemoprophylaxis is necessary even if the contact has been previously vaccinated, as vaccines do not protect against all serogroups (especially Serogroup B).

Question 94: World Tuberculosis Day is celebrated on which date?

A. 24th March (Correct Answer)
B. 7th April
C. 22nd April
D. 1st December

Explanation: **Explanation:** **Correct Option: A (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 bacterium that causes tuberculosis. This discovery was a turning point in medical history, paving the way for the diagnosis and treatment of the disease. **Analysis of Incorrect Options:** * **B. 7th April:** This is **World Health Day**, marking the founding anniversary of the World Health Organization (WHO) in 1948. * **C. 22nd April:** This is **Earth Day**, an international event focused on environmental protection. * **D. 1st December:** This is **World AIDS Day**, dedicated to raising awareness of the AIDS pandemic caused by HIV infection. **High-Yield Clinical Pearls for NEET-PG:** * **Etiology:** TB is caused by the *Mycobacterium tuberculosis* complex (Acid-Fast Bacilli). * **National Program:** In India, the program is currently known as the **National Tuberculosis Elimination Program (NTEP)**, formerly RNTCP. * **Goal:** India aims to **eliminate TB by 2025**, five years ahead of the global Sustainable Development Goal (SDG) of 2030. * **Diagnostic Gold Standard:** **CBNAAT (GeneXpert)** is the preferred initial diagnostic test for TB and Rifampicin resistance. * **Public Health Notification:** TB is a **notifiable disease** in India since 2012. * **Nikshay Poshan Yojana:** A central scheme providing ₹500/month nutritional support to TB patients.

Question 95: Which of the following is true for Directly Observed Treatment, Short-course (DOTS)?

A. Treatment is provided under direct supervision (Correct Answer)
B. All patients receive the exact same treatment regimen
C. Streptomycin is administered to every patient
D. The treatment regimen is administered daily

Explanation: **Explanation:** **Directly Observed Treatment, Short-course (DOTS)** is the internationally recommended strategy for tuberculosis control. The core principle of DOTS is to ensure **treatment adherence** and prevent the development of multi-drug resistant TB (MDR-TB). 1. **Why Option A is Correct:** The hallmark of DOTS is that a trained health worker or a designated community member (DOT provider) watches the patient swallow their medication. This **direct supervision** ensures that the patient completes the full course of treatment, addressing the primary cause of treatment failure: non-compliance. 2. **Why Other Options are Incorrect:** * **Option B:** Patients do not receive the "exact same" regimen. Treatment is categorized based on the type of TB (e.g., Drug-Sensitive vs. Drug-Resistant). Under RNTCP/NTEP, regimens differ for adults versus pediatric patients (weight-band based dosing). * **Option C:** Streptomycin is an injectable aminoglycoside and is **not** administered to every patient. It was previously used in Category II (re-treatment) cases, but current guidelines prioritize oral regimens and have largely phased out Streptomycin due to toxicity and the shift toward DST-guided (Drug Susceptibility Testing) treatment. * **Option D:** While the current **NTEP (National TB Elimination Program)** in India has shifted to a **Daily Regimen** using Fixed-Dose Combinations (FDCs), historically DOTS was famous for its Intermittent Regimen (thrice weekly). Therefore, "daily administration" is a feature of the current *regimen*, but "direct supervision" remains the defining *definition* of DOTS itself. **High-Yield Pearls for NEET-PG:** * **5 Pillars of DOTS:** Political commitment, Good quality microscopy, Uninterrupted supply of drugs, Recording/Reporting system, and Direct observation. * **NTEP Update:** India has moved from "Intermittent" to **Daily Dosing** using **FDCs** (Fixed-Dose Combinations) based on weight bands. * **Ethambutol** is now given in both the Intensive Phase and the Continuation Phase for new cases.

Question 96: All of the following are the targets of the STOP TB STRATEGY partnership except:

A. Achieve a diagnosis rate of > 70% and a cure rate of > 85% by 2005
B. Reduce prevalence to < 150 per 100,000 population per year by 2010
C. Lower deaths to < 1 per 100,000 population per year by 2010
D. Achieve global incidence of TB disease < 1 case per million population per year (Correct Answer)

Explanation: The **Stop TB Strategy (2006–2015)** was launched by the WHO to build upon the DOTS strategy and address challenges like HIV-associated TB and MDR-TB. Understanding the specific timelines and targets is crucial for NEET-PG. ### **Explanation of the Correct Answer** **Option D** is the correct answer because it represents the goal of the **"End TB Strategy" (2016–2035)**, not the Stop TB Strategy. The target of achieving an incidence of **< 1 case per million population** is the definition of **TB Elimination**, which is the ultimate vision for the year **2050**. ### **Analysis of Incorrect Options** * **Option A:** This was the primary interim target for the year **2005**. The goal was to detect at least 70% of new sputum smear-positive cases and cure at least 85% of them. * **Option B:** One of the Millennium Development Goal (MDG) linked targets for **2015** (often cited in 2010 mid-term reviews) was to reduce the prevalence of TB to less than 150 per 100,000. * **Option C:** Reducing TB mortality to less than 1 per 100,000 population was a specific target aimed at reducing the global burden of deaths by 50% relative to 1990 levels. ### **High-Yield Clinical Pearls for NEET-PG** * **Stop TB Strategy (2006-2015):** Focused on "Halving the prevalence and deaths" compared to 1990 levels. * **End TB Strategy (2016-2035):** * **90% reduction** in TB deaths by 2035 (compared to 2015). * **80% reduction** in TB incidence rate by 2030. * **Zero** catastrophic costs for TB-affected families. * **National Strategic Plan (India):** Aims for TB elimination in India by **2025** (5 years ahead of the global target).

Question 97: According to guidelines for infant care programs addressing lower abdominal pain, what is the color code of the treatment kit?

A. White
B. Green
C. Yellow (Correct Answer)
D. Grey

Explanation: **Explanation:** The question refers to the **Syndromic Management of Sexually Transmitted Infections (STIs) and Reproductive Tract Infections (RTIs)** under the National AIDS Control Programme (NACP). This approach uses standardized color-coded kits to provide immediate treatment based on clinical symptoms rather than waiting for laboratory confirmation. **1. Why Yellow is Correct:** The **Yellow Kit (Kit 6)** is specifically designated for the management of **Lower Abdominal Pain** in women, which clinically indicates **Pelvic Inflammatory Disease (PID)**. It contains a combination of three drugs to cover common pathogens like *N. gonorrhoeae*, *C. trachomatis*, and anaerobes: * **Cefixime** (400 mg, single dose) * **Metronidazole** (400 mg, twice daily for 14 days) * **Doxycycline** (100 mg, twice daily for 14 days) **2. Why other options are incorrect:** * **White (Kit 1):** Used for **Urethral Discharge** (males), Anorectal discharge, or Cervicitis. Contains Azithromycin and Cefixime. * **Green (Kit 2):** Used for **Vaginal Discharge** (Candidiasis/Trichomoniasis/Bacterial Vaginosis). Contains Secnidazole and Fluconazole. * **Grey (Kit 3):** Used for **Genital Ulcer Disease (Non-Herpetic)**. Contains Azithromycin and Benzathine Penicillin. **Clinical Pearls for NEET-PG:** * **Red Kit (Kit 4):** For Genital Ulcers in patients allergic to Penicillin (uses Doxycycline instead). * **Blue Kit (Kit 5):** For Genital Ulcers (Herpetic). Contains Acyclovir. * **Black Kit (Kit 7):** For Inguinal Bubo. Contains Doxycycline and Azithromycin. * **Key Concept:** Syndromic management is cost-effective, ensures same-day treatment, and breaks the chain of transmission in resource-limited settings.

Question 98: Which of the following statements about hepatitis B is FALSE?

A. Vertical transmission is more important than horizontal transmission. (Correct Answer)
B. The communicable period lasts for months.
C. The virus can be found in the blood 1 month before jaundice appears.
D. The age of onset determines the prognosis.

Explanation: **Explanation:** In Hepatitis B (HBV) epidemiology, the mode of transmission varies significantly by region. In **low-prevalence areas** (like India and the West), **horizontal transmission** (via percutaneous/permucosal routes, sexual contact, and contaminated needles) is the primary driver of the epidemic. While vertical (mother-to-child) transmission carries a high risk of chronicity, it is not the most frequent route globally compared to horizontal spread. Therefore, statement A is false. **Analysis of other options:** * **Option B:** HBV is highly infectious. The communicable period is prolonged, lasting throughout the incubation period and the clinical phase. In chronic carriers, the virus can remain communicable for **years or even a lifetime**. * **Option C:** HBsAg (the first marker) typically appears in the blood **2 to 8 weeks before** the onset of jaundice or clinical symptoms, making this statement accurate. * **Option D:** The age of infection is the **strongest predictor of chronicity**. Approximately 90% of infected infants become chronic carriers, compared to only 5–10% of adults. Thus, age directly determines the long-term prognosis. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** 30–180 days (Average: 75 days). * **First Marker:** HBsAg is the first to appear; **Anti-HBs** indicates immunity (via recovery or vaccination). * **Window Period:** The interval when HBsAg is cleared but Anti-HBs hasn't appeared; **Anti-HBc IgM** is the only diagnostic marker during this phase. * **Infectivity Marker:** **HBeAg** indicates high viral replication and maximum infectivity.

Question 99: In which anatomical location is the tuberculin test typically performed?

A. Dorsum of the left arm
B. Dorsum of the right arm
C. Ventral aspect of the left forearm (Correct Answer)
D. Ventral aspect of the right forearm

Explanation: ### Explanation The **Tuberculin Skin Test (TST)**, also known as the **Mantoux test**, is the standard method for determining whether a person is infected with *Mycobacterium tuberculosis*. **1. Why the Correct Answer is Right:** The **ventral (volar) aspect of the left forearm** is the internationally standardized site for the Mantoux test. * **Anatomical Advantage:** The skin on the ventral forearm is thin, hairless, and lacks major superficial veins, making it ideal for performing a precise **intradermal injection** (using a 26 or 27-gauge needle) to produce a distinct wheal (6–10 mm). * **Standardization:** The **left arm** is chosen by convention to ensure uniformity in clinical practice, making it easier for healthcare providers to locate and read the induration 48–72 hours later. **2. Why the Other Options are Wrong:** * **Dorsum of the arm (Options A & B):** The dorsal surface has thicker skin, more hair follicles, and a higher density of subcutaneous fat, which interferes with the intradermal technique and the subsequent measurement of induration. * **Ventral aspect of the right forearm (Option D):** While physiologically identical to the left, the right arm is avoided by convention to prevent confusion with other diagnostic tests or vaccinations (like BCG, which is traditionally given in the left deltoid). **3. High-Yield Clinical Pearls for NEET-PG:** * **Technique:** 0.1 ml of **PPD (Purified Protein Derivative)** containing **5 TU (Tuberculin Units)** is injected intradermally. * **Reading the Result:** Only the **induration** (palpable hardening) is measured, NOT the erythema (redness). * **Interpretation:** * **≥5 mm:** Positive in HIV+ patients or recent contacts of TB cases. * **≥10 mm:** Positive in high-risk populations (healthcare workers, IV drug users). * **≥15 mm:** Positive in persons with no known risk factors. * **False Negative:** Can occur in miliary TB, malnutrition, sarcoidosis, or immunosuppression (Anergy).

Question 100: HIV infection is known to be transmitted during all of the following EXCEPT?

A. Breast feeding
B. Child birth
C. Heterosexual intercourse
D. Kissing (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Kissing**. HIV (Human Immunodeficiency Virus) is transmitted through specific body fluids, including blood, semen, vaginal secretions, and breast milk. **Why Kissing is the Correct Answer:** Social kissing (dry kissing) does not transmit HIV because the virus is not present in sufficient concentrations in **saliva** to cause infection. While extremely rare, transmission during "deep" or "French" kissing is only theoretically possible if both partners have significant bleeding gums or open sores, allowing direct blood-to-blood contact. In the context of standard medical examinations, kissing is considered a non-transmission route. **Analysis of Incorrect Options:** * **Breast feeding:** This is a known route of **Vertical Transmission** (Post-natal). The risk of transmission via breast milk is approximately 5–20%. * **Child birth:** This is the most common period for vertical transmission (Intra-partum). Transmission occurs through contact with infected maternal blood and vaginal secretions during delivery. * **Heterosexual intercourse:** Globally, this is the **most common mode of transmission**. The risk is higher for the receptive partner due to a larger surface area of mucous membrane exposure. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most common mode of transmission (Global & India):** Heterosexual route. 2. **Highest risk of transmission per act:** Blood transfusion (approx. 90-95%). 3. **Vertical Transmission:** Overall risk without intervention is 15–45%. This can be reduced to <1% with effective Antiretroviral Therapy (ART). 4. **Window Period:** The time between infection and the appearance of detectable antibodies (usually 2–8 weeks). 5. **Rule of Thumb:** HIV is **NOT** transmitted by fomites, insects (mosquitoes), swimming pools, or sharing utensils.

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