Infectious Diseases Practice Questions

Q: What is the recommended period of isolation for shigellosis?

Until 3 consecutive negative stool cultures.. **Explanation:** Shigellosis (Bacillary Dysentery) is a highly infectious disease caused by *Shigella* species. The primary reason for stringent isolation protocols is the **low infectious dose**; as few as 10–100 organisms can cause clinical disease. **Why Option C is Correct:** According to standard public health guidelines (and Park’s Textbook of Preventive and Social Medicine), a case of shigellosis is considered non-infectious only after clinical recovery and the documentation of **three consecutive negative stool cultures** taken at intervals of at least 24 hours. This rigorous requirement ensures that the patient is not a "convalescent carrier," thereby preventing outbreaks, especially in high-risk settings like daycare centers or food-handling establishments. **Why Other Options are Incorrect:** * **Option A & B:** A single or even two negative cultures are insufficient because *Shigella* shedding can be intermittent. Relying on fewer than three cultures increases the risk of a false negative, potentially allowing a carrier to return to the community while still being infectious. * **Option D:** This is incorrect as specific isolation and clearance criteria are well-established for enteric pathogens. **High-Yield Clinical Pearls for NEET-PG:** * **Mode of Transmission:** Primarily fecal-oral (the "4 Fs": Fingers, Flies, Food, and Fomites). * **Incubation Period:** Usually 1–7 days (commonly 48 hours). * **Drug of Choice:** Ciprofloxacin is generally the first-line treatment, though resistance is increasing (Azithromycin or Ceftriaxone are alternatives). * **Key Difference:** Unlike Typhoid (which requires 3 negative cultures for clearance in food handlers), Shigellosis is more acutely infectious due to its extremely low threshold for infection.

Q: The '3 by 5 Initiative' was launched in developing countries to combat which of the following?

HIV/AIDS. **Explanation:** The **'3 by 5' Initiative** was a global health strategy launched by the **World Health Organization (WHO)** and **UNAIDS** in December 2003. The specific goal was to provide antiretroviral therapy (ART) to **3 million people** living with **HIV/AIDS** in low- and middle-income countries by the end of **2005**. It was a landmark effort to shift the focus from HIV prevention alone to include equitable access to life-saving treatment. **Analysis of Options:** * **HIV/AIDS (Correct):** The initiative targeted the treatment gap in developing nations, promoting the "public health approach" to ART, which simplified treatment regimens and clinical monitoring to scale up delivery. * **Malaria:** While the "Roll Back Malaria" partnership exists, the '3 by 5' branding is specific to HIV treatment targets. * **SARS:** The SARS outbreak (2003) led to strengthened International Health Regulations (IHR), but no specific '3 by 5' initiative was associated with it. * **Tuberculosis:** TB control is primarily managed through the DOTS (Directly Observed Treatment, Short-course) strategy and the "End TB" strategy. **High-Yield Clinical Pearls for NEET-PG:** * **Goal:** 3 million people on ART by 2005. * **Current Target:** The '3 by 5' initiative paved the way for the **95-95-95 targets** (95% diagnosed, 95% on ART, 95% virally suppressed by 2030). * **ART in India:** Free ART was launched in India on **April 1, 2004**, as part of this global momentum. * **NACP Phase:** This initiative coincided with the transition between NACP-II and NACP-III in India.

Q: SIDA functions for which of the following?

Tuberculosis. **Explanation:** The correct answer is **Tuberculosis (B)**. **SIDA** stands for the **Swedish International Development Cooperation Authority**. In the context of public health in India, SIDA has been a major international partner specifically for the **National Tuberculosis Elimination Programme (NTEP)**, formerly known as the RNTCP. 1. **Why Tuberculosis is correct:** SIDA played a pivotal role in the 1990s by providing financial and technical support for the pilot projects of **DOTS (Directly Observed Treatment, Short-course)** in India. Their support was instrumental in the phased expansion of the RNTCP across the country, focusing on drug procurement and laboratory strengthening. 2. **Why other options are incorrect:** * **Leprosy:** The primary international partner for the National Leprosy Eradication Programme (NLEP) is the **WHO** and **ILEP** (International Federation of Anti-Leprosy Associations), along with significant support from the Sasakawa Health Foundation. * **Blindness:** The National Programme for Control of Blindness (NPCB) receives major international assistance from the **World Bank** and organizations like **DANIDA** (Danish International Development Agency). * **Agriculture:** While SIDA does fund rural development, in the medical curriculum and NEET-PG context, it is strictly associated with its landmark contribution to the TB control program. **High-Yield Clinical Pearls for NEET-PG:** * **DANIDA:** Associated with Blindness Control and National Family Welfare programs. * **USAID:** Associated with HIV/AIDS (PACE project) and Maternal & Child Health. * **Rockefeller Foundation:** Historically famous for Hookworm control and supporting the development of the Yellow Fever vaccine (17-D strain). * **CARE:** Primarily focuses on Integrated Child Development Services (ICDS) and nutrition.

Q: A negative Mantoux test is indicated by an induration measuring less than what diameter?

5 mm. **Explanation:** The Mantoux test (Tuberculin Skin Test) is a screening tool for *Mycobacterium tuberculosis* infection. It involves the intradermal injection of 0.1 ml of 5 TU (Tuberculin Units) of Purified Protein Derivative (PPD). The result is read 48–72 hours later by measuring the **diameter of induration** (palpable hardening), not erythema. **1. Why 5 mm is the correct answer:** According to standard diagnostic criteria (including WHO and RNTCP/NTEP guidelines), an induration of **less than 5 mm** is considered a **negative** result. It indicates that the individual has likely not been infected with TB or has a suppressed immune response. **2. Analysis of Incorrect Options:** * **10 mm (Option A):** This is the threshold for a **positive** result in "high-risk" groups, such as healthcare workers, residents of high-prevalence areas, or patients with clinical conditions like diabetes or silicosis. * **15 mm (Option B):** This is the threshold for a **positive** result in individuals with **no known risk factors** for TB. * **20 mm (Option C):** This is significantly higher than the standard diagnostic cut-off. An induration of this size often indicates a strong positive reaction or a "vesicular" reaction, suggesting a high likelihood of active infection or extreme sensitivity. **3. High-Yield Clinical Pearls for NEET-PG:** * **False Negatives:** Can occur in miliary TB, malnutrition, HIV/AIDS (due to anergy), and recent viral infections (e.g., Measles). * **False Positives:** Can occur due to prior **BCG vaccination** or infection with Non-Tuberculous Mycobacteria (NTM). * **HIV Patients:** In HIV-positive individuals, an induration of **≥ 5 mm** is considered positive due to their compromised immune status. * **Reading:** Always measure the transverse diameter of the induration using the "pen method."

Q: What is the Category II treatment for tuberculosis?

2HRZES. ### Explanation **Concept:** Under the Revised National Tuberculosis Control Programme (RNTCP), Category II was historically designed for **previously treated cases** (Relapse, Treatment after Failure, and Treatment After Loss to Follow-up). The goal was to provide a more intensive regimen to combat potential drug resistance. **Why 2HRZES is Correct:** The Category II regimen consisted of an **Intensive Phase (IP)** lasting 3 months and a **Continuation Phase (CP)** lasting 5 months. * **2HRZES:** During the first 2 months of the IP, five drugs were given: Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), Ethambutol (E), and an injection of Streptomycin (S). * This was followed by 1 month of **HRZE** (without Streptomycin) and 5 months of **HRE** (CP). **Analysis of Incorrect Options:** * **B (1HRZE):** This represents only the third month of the Intensive Phase in Category II, not the entire regimen. * **C (5HRZ):** This does not follow any standard RNTCP protocol. The Continuation Phase for Category II was actually 5HRE. **High-Yield Clinical Pearls for NEET-PG:** 1. **Current Status:** As per the latest **National Strategic Plan (NSP)** and WHO guidelines, the distinction between Category I and Category II has been **abolished**. 2. **Universal Drug Susceptibility Testing (UDST):** All patients are now screened for Rifampicin resistance at the time of diagnosis. 3. **Current Protocol:** "Previously treated" patients are no longer given Streptomycin (Category II). Instead, if they are drug-sensitive, they receive the same 6-month regimen as new cases (2HRZE / 4HRE). If drug-resistant, they are put on specific MDR-TB regimens. 4. **Drug Codes:** H (Isoniazid), R (Rifampicin), Z (Pyrazinamide), E (Ethambutol), S (Streptomycin).

Question 1

What is the recommended period of isolation for shigellosis?

Accepted Answer

Until 3 consecutive negative stool cultures.

Answer

Until 1 negative stool culture.

Answer

Until 2 consecutive negative stool cultures.

Answer

None of the above.

Question 2

The '3 by 5 Initiative' was launched in developing countries to combat which of the following?

Accepted Answer

HIV/AIDS

Answer

Malaria

Answer

SARS

Answer

Tuberculosis

Question 3

Class II exposure in animal bites includes which of the following?

Accepted Answer

Scratches without oozing of blood

Answer

Bites from wild animals

Answer

Licks on a fresh wound

Answer

Scratch with oozing of blood

Question 4

Transmission of an agent by vectors is facilitated by which of the following mechanisms, except one?

Accepted Answer

Ingestion of infected material

Answer

Contamination with body fluids of vectors

Answer

Scratching-in of infected feces

Answer

Regurgitation

Question 5

SIDA functions for which of the following?

Accepted Answer

Tuberculosis

Answer

Leprosy

Answer

Blindness

Answer

Agriculture

Question 6

What is the recommended dose of Rabies immunoglobulin?

Accepted Answer

20 IU/kg body weight

Answer

10 IU/Kg body weight

Answer

15 IU/kg body weight

Answer

25 IU/kg body weight

Question 7

"3 BY 5 target" approach refers to?

Accepted Answer

Providing antiretroviral therapy to 3 million people by 2005

Answer

Providing 3 antiretroviral drugs to all patients by 2005

Answer

Providing 3 antiretroviral drugs to all patients

Answer

All of the above

Question 8

A negative Mantoux test is indicated by an induration measuring less than what diameter?

Accepted Answer

5 mm

Answer

10 mm

Answer

15 mm

Answer

20 mm

Question 9

What is the Category II treatment for tuberculosis?

Accepted Answer

2HRZES

Answer

1HRZE

Answer

5HRZ

Answer

None

Question 10

Which of the following conditions does NOT require isolation?

Accepted Answer

Pneumonic plague

Answer

Mumps

Answer

Measles

Answer

Hepatitis A

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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