Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 651: What is the date observed as World AIDS Day?

A. 7 April
B. 3 May
C. 5 June
D. 1 December (Correct Answer)

Explanation: ***Correct Answer: 1 December*** - **World AIDS Day** is observed annually on **December 1st** to raise awareness about the AIDS pandemic caused by the spread of **HIV infection** and to mourn those who have died of the disease. - This date was chosen by James W. Bunn and Thomas Netter, two public information officers for the Global Programme on AIDS at the **World Health Organization (WHO)**, in August 1987. - The first World AIDS Day was observed in **1988**. *Incorrect: 7 April* - **April 7th** is recognized as **World Health Day**, which marks the anniversary of the founding of the World Health Organization (WHO) in 1948. - This day focuses on a specific health theme each year to highlight a priority area of concern for the WHO. *Incorrect: 3 May* - **May 3rd** is celebrated as **World Press Freedom Day**, which aims to raise awareness of the importance of freedom of the press and to remind governments of their duty to respect and uphold the right to freedom of expression. - This date does not have a direct association with AIDS awareness or public health campaigns. *Incorrect: 5 June* - **June 5th** is designated as **World Environment Day**, the United Nations' principal vehicle for encouraging worldwide awareness and action for the protection of our environment. - This day is focused on environmental issues and sustainability, not specifically on HIV/AIDS.

Question 652: All of the following are anthropozoonosis except

A. Rabies
B. Plague
C. Anthrax
D. Schistosomiasis (Correct Answer)

Explanation: ***Schistosomiasis*** - This is a **human-to-human** disease, even though it involves an intermediate **snail host**. - Its life cycle does not involve transmission of pathogens from vertebrate animals to humans. *Rabies* - Rabies is a classic **anthropozoonosis**, transmitted to humans primarily through the saliva of infected animals, most commonly **dogs** and **bats**. - It involves a pathogen (rabies virus) that cycles between animals and can be transmitted to humans. *Plague* - Plague is an **anthropozoonosis** caused by *Yersinia pestis*, typically transmitted from **rodents** (e.g., rats) to humans via flea bites. - The disease maintains a natural reservoir in wild rodent populations, making it a prime example of animal-to-human transmission. *Anthrax* - Anthrax is an **anthropozoonosis** caused by *Bacillus anthracis*, transmitted to humans from infected **livestock** (e.g., cattle, sheep). - Humans usually acquire the infection through contact with infected animals or their products, or by inhaling spores.

Question 653: What is the recommended concentration of diethylcarbamazine in DEC medicated salt for the treatment of endemic filariasis?

A. 5-10 gm/kg
B. 0.1-0.2 gm/kg (Correct Answer)
C. 0.5-1.0 gm/kg
D. 2-4 gm/kg

Explanation: ***0.1-0.2 gm/kg*** - The recommended concentration of **diethylcarbamazine (DEC)** in medicated salt for the treatment of endemic filariasis is typically 0.1-0.2 gm/kg of salt. - This low, sustained dose helps to gradually eliminate microfilariae and prevent transmission without causing severe adverse reactions. *0.5-1.0 gm/kg* - This concentration is significantly higher than the standard recommendation for mass drug administration using DEC medicated salt. - Such a higher dose would increase the risk of adverse drug reactions, making it unsuitable for community-wide use. *2-4 gm/kg* - This concentration is far too high for safe and effective use in DEC medicated salt programs. - Administering DEC at this level would likely lead to widespread and potentially severe side effects among the treated population. *5-10 gm/kg* - Concentrations in this range are excessively high and would be toxic if used in medicated salt for filariasis treatment. - This would result in widespread and severe adverse events, making it an unacceptable option.

Question 654: All following are at-risk group adults meriting Hepatitis B vaccination in low endemic areas except for which of the following?

A. Medical/nursing personnel
B. Patients with chronic liver disease
C. Diabetics on insulin (Correct Answer)
D. Patients on chronic hemodialysis

Explanation: ***Diabetics on insulin*** - This is the correct answer as the exception based on **guidelines at the time of this exam (2012)**. - At that time, diabetics were **not routinely listed** as a standard at-risk group for hepatitis B vaccination in low endemic areas, though the ACIP was beginning to recognize increased risk in this population. - **Current Update (Post-2012):** The **CDC/ACIP now recommends** hepatitis B vaccination for all previously unvaccinated adults with diabetes aged 19-59 years, due to documented increased risk of HBV infection associated with: - Shared blood glucose monitoring devices - Assisted blood glucose monitoring in healthcare settings - Outbreak investigations showing higher transmission rates - For the purpose of this historical exam question, diabetics were the exception among the listed groups. *Medical/nursing personnel* - Healthcare workers are at **high occupational risk** due to frequent exposure to blood and body fluids. - This has been a **standard, long-standing recommendation** for HBV vaccination regardless of endemic status. - The risk remains present even in low endemic areas due to potential exposure to infected patients. *Patients with chronic liver disease* - Individuals with pre-existing chronic liver disease are at risk of **severe outcomes** if they acquire hepatitis B infection. - Superimposed acute HBV infection can lead to: - Rapid progression to cirrhosis - Acute-on-chronic liver failure - Hepatocellular carcinoma - Vaccination is **crucial for prevention** and has been a standard recommendation. *Patients on chronic hemodialysis* - Hemodialysis patients face **elevated risk** of HBV acquisition due to: - Frequent vascular access procedures - Prolonged time in healthcare settings - Potential for nosocomial transmission in dialysis units - Their **immunocompromised state** increases risk of chronic infection and complications. - Vaccination is a **standard preventive measure** in this population.

Question 655: The primary reservoir for leptospirosis transmission is:

A. Rat (Correct Answer)
B. Cat
C. Dog
D. Fish

Explanation: ***Correct Answer: Rat*** - **Rats** (and other rodents) are considered the primary natural reservoir for *Leptospira* bacteria worldwide and are **asymptomatic carriers**. - They excrete the bacteria in their urine, contaminating water and soil, which serves as the main source of human infection. *Incorrect: Cat* - While cats can become infected with *Leptospira*, they are **not typically considered significant reservoirs** for human transmission. - Their role in the epidemiologic cycle of leptospirosis is generally minor compared to rodents and some other mammals. *Incorrect: Dog* - **Dogs** can contract leptospirosis and excrete the bacteria in their urine, posing a risk to humans, but they are generally considered **incidental hosts or secondary reservoirs**, not the primary one. - Vaccination in dogs helps reduce their role in transmission. *Incorrect: Fish* - **Fish are not known to be reservoirs** for *Leptospira* bacteria. - Leptospirosis is primarily transmitted through contact with infected animal urine, not aquatic life like fish.

Question 656: What is the recommended Aedes Aegypti index for preventing Yellow Fever transmission?

A. Less than 1% (Correct Answer)
B. Less than 5%
C. Less than 10%
D. Less than 20%

Explanation: ***Less than 1%*** - An **Aedes Aegypti index** of **less than 1%** is the recommended threshold by WHO to effectively prevent Yellow Fever transmission. - Maintaining the vector index (House Index) below this critical level significantly reduces the chances of epidemic transmission. - This stringent target is essential for breaking the transmission cycle in endemic areas. *Less than 5%* - While an index of less than 5% represents moderate control, it is insufficient for reliable Yellow Fever prevention. - This threshold may be acceptable for the Breteau Index (measured differently), but for the House Index, 1% is the standard. - At this level, there remains significant risk of transmission during favorable conditions. *Less than 10%* - An index of **less than 10%** is considered inadequate for prevention of Yellow Fever transmission. - This level carries a substantial risk of outbreaks, as the vector population remains high enough to support sustained transmission. - Urgent vector control interventions are needed at this level. *Less than 20%* - An **Aedes Aegypti index** of less than 20% indicates a high-risk environment for Yellow Fever transmission. - This level is far above the recommended threshold and suggests a critical need for immediate and aggressive vector control measures. - At this level, epidemic transmission is highly likely if the virus is introduced.

Question 657: Which of the following is not typically screened for in blood donations?

A. HIV
B. HBV
C. HCV
D. Epstein-Barr Virus (EBV) (Correct Answer)

Explanation: ***Epstein-Barr Virus (EBV)*** ✓ - EBV is **NOT routinely screened** for in blood donations in India and most countries - While EBV is a common virus (>90% adults are seropositive), it is **not considered a major transfusion-transmitted infection** - The virus is primarily transmitted through saliva; transfusion-associated EBV transmission is **extremely rare and usually not clinically significant** in immunocompetent recipients - Risk-benefit analysis does not support routine screening due to **high prevalence, low clinical impact, and cost considerations** - EBV screening may only be considered for specific recipients (e.g., severely immunocompromised patients) *HIV* - **Routinely screened** in all blood donations worldwide - Screening includes HIV-1 and HIV-2 antibodies and/or HIV antigen/RNA testing - Transfusion-transmitted HIV causes AIDS with severe consequences - Mandatory screening under the Drugs and Cosmetics Act in India *HBV* - **Routinely screened** in all blood donations - Screening includes HBsAg (Hepatitis B surface antigen) testing, and often anti-HBc or HBV DNA - Can cause acute and chronic hepatitis, cirrhosis, and hepatocellular carcinoma - Mandatory screening in India and globally *HCV* - **Routinely screened** in all blood donations - Screening includes anti-HCV antibodies and/or HCV RNA (nucleic acid testing) - Major cause of chronic hepatitis, cirrhosis, and liver cancer - Mandatory screening under blood safety regulations

Question 658: What is the most commonly reported bacterial sexually transmitted infection?

A. HSV
B. HIV
C. Syphilis
D. Chlamydia (Correct Answer)

Explanation: ***Correct: Chlamydia*** - **Chlamydia trachomatis** is the most frequently reported bacterial STI in many countries, often being **asymptomatic** and thus easily spread - Its high prevalence is due to efficient transmission and the widespread use of sensitive diagnostic tests that detect infections in asymptomatic individuals - Accounts for the majority of reported bacterial STI cases globally *Incorrect: HSV* - **Herpes Simplex Virus (HSV)** is a **viral STI**, not bacterial, and is characterized by recurrent outbreaks of **genital ulcers** or sores - While common, it does not qualify as a bacterial infection and is often not laboratory-confirmed due to mild or subclinical presentations *Incorrect: HIV* - **Human Immunodeficiency Virus (HIV)** is also a **viral STI**, not bacterial, that attacks the immune system leading to AIDS - Although highly impactful, HIV is not a bacterial infection and has lower incidence rates compared to Chlamydia *Incorrect: Syphilis* - **Syphilis**, caused by the bacterium **Treponema pallidum**, is a serious bacterial STI that can have long-term complications if untreated - While its incidence has been increasing in some regions, it is significantly less common than **Chlamydia** in terms of overall reported cases

Question 659: National Leprosy Eradication Programme was started in -

A. 1949
B. 1955
C. 1973
D. 1983 (Correct Answer)

Explanation: **Correct: 1983** - The **National Leprosy Eradication Programme (NLEP)** was launched in India in **1983** - Its goal was to eliminate leprosy as a public health problem by reducing its prevalence rate to less than 1 case per 10,000 population - This marked the shift from control to eradication strategy with the introduction of **Multi-Drug Therapy (MDT)** *Incorrect: 1949* - This year is not associated with the inception of a national leprosy eradication program in India - While efforts against leprosy existed, a comprehensive national program was not established at this time *Incorrect: 1955* - The **National Leprosy Control Programme (NLCP)** was launched in India in **1955** - This was a control program, preceding the eradication program, focusing on diagnosis and treatment with Dapsone monotherapy - NLCP was later upgraded to NLEP in 1983 *Incorrect: 1973* - This year is not cited as the start date for the national leprosy eradication program in India - The focus shifted from control to eradication in 1983 with the adoption of WHO-recommended MDT

Question 660: What is the Chandler's Index for Hookworm that indicates a significant health problem?

A. > 200
B. > 100
C. > 300
D. > 50 (Correct Answer)

Explanation: ***> 50*** - A Chandler's Index of **> 50** indicates a significant public health problem due to **hookworm infection**. - **Chandler's Index** is calculated as the **average egg count per person in a community** (total hookworm eggs counted ÷ number of persons examined), used to assess the population-level burden of hookworm infection. - A value **> 50** suggests that the community has a significant hookworm problem requiring public health intervention. *> 300* - This value is significantly higher than the threshold for a significant public health problem and would indicate an **extremely severe burden of infection**. - While this represents a very high Chandler's Index, it's not the standard cut-off for defining a "significant" health problem (which is the lower threshold of >50). *> 200* - A Chandler's Index of **> 200** would denote a very high intensity of hookworm infection in the community. - However, this is not the standard threshold used to define when hookworm becomes a "significant" public health issue - the threshold is lower at >50. *> 100* - A Chandler's Index of **> 100** represents a substantial level of hookworm infection within a population. - However, the widely recognized cutoff for a "significant health problem" is **> 50**, indicating public health concern even at this moderate level of community infection burden.

Practice by Chapter

Communicable Disease Control Principles

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Vector-Borne Diseases

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Water-Borne Diseases

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Air-Borne Diseases

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Zoonotic Diseases

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Sexually Transmitted Infections

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HIV/AIDS Control Program

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Tuberculosis Control

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Leprosy Elimination

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Emerging and Re-emerging Infections

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Hospital-Acquired Infections

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Integrated Disease Surveillance Project

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