Infectious Diseases — MCQs
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Risk of transmission from single percutaneous exposure to blood for HIV is:-
ICD-10 chapter 1 describes?
A person with tuberculosis on domiciliary treatment is expected to do all, except?
Zoonotic diseases are -
Which of the following is NOT true about varicella infection?
Chance of acquiring Hepatitis B infection by eye splash with Hepatitis B positive patient blood:
According to WHO guidelines, the minimum recommended denier count for polyethylene mosquito nets (LLINs) for effective malaria prevention is:
Hepatitis B infection spreads through all of the following routes except
Which one of the following is an emerging viral disease?
A night blood survey is done in -
Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 381: Risk of transmission from single percutaneous exposure to blood for HIV is:-
- A. 2.7-10%
- B. 6-30%
- C. 0.1 - 0.36% (Correct Answer)
- D. 0.4-5%
Explanation: ***0.1 - 0.36%*** - The risk of **HIV transmission** from a single percutaneous exposure (e.g., needle stick injury) to infected blood is approximately **0.3%** (range 0.1% to 0.36%) according to CDC guidelines. - This relatively low risk is due to the small inoculum size and lower viral concentration in needle stick injuries compared to other exposures. - Post-exposure prophylaxis (PEP) can further reduce this already low transmission risk. *2.7-10%* - This range is significantly **higher** than the established risk for percutaneous HIV transmission. - This percentage is more aligned with **Hepatitis C virus (HCV)** transmission risk, which is approximately 1.8% (range 0-7%). *6-30%* - This range is substantially **overstated** for HIV transmission from percutaneous exposure. - These percentages reflect the transmission risk for **Hepatitis B virus (HBV)**, which has a much higher transmission rate (6-30%) from needle stick injuries. *0.4-5%* - While 0.4% is close to some reported upper limits, the 5% figure is **much higher** than established estimates for percutaneous HIV transmission. - This range incorrectly combines different risk estimates and does not accurately represent single percutaneous HIV exposure risk.
Question 382: ICD-10 chapter 1 describes?
- A. Poisoning and consequences
- B. Psychiatric diseases
- C. Diseases of the nervous system
- D. Infectious and parasitic diseases (Correct Answer)
Explanation: ***Infectious and parasitic diseases*** - **ICD-10 Chapter 1** specifically categorizes codes related to **infectious and parasitic diseases**, ranging from A00 to B99. - This chapter covers a broad spectrum of conditions caused by microorganisms and parasites, such as bacterial, viral, fungal, and protozoal infections. *Poisoning and consequences* - **Poisoning and certain other consequences of external causes** are covered in ICD-10 Chapter 19, with codes typically ranging from T36-T65 for poisoning by drugs, medicaments, and biological substances. - This chapter focuses on injuries, poisoning, and certain other consequences of external causes, not infectious diseases. *Psychiatric diseases* - **Mental and behavioral disorders** (often referred to as psychiatric diseases) are described in ICD-10 Chapter 5, with codes ranging from F00 to F99. - This chapter includes conditions such as mood disorders, anxiety disorders, schizophrenia, and substance-related disorders. *Diseases of the nervous system* - **Diseases of the nervous system** are categorized in ICD-10 Chapter 6, with codes ranging from G00 to G99. - This chapter covers conditions affecting the brain, spinal cord, nerves, and neuromuscular junctions, such as stroke, epilepsy, and Parkinson's disease.
Question 383: A person with tuberculosis on domiciliary treatment is expected to do all, except?
- A. Collect drugs regularly
- B. Dispose sputum safely
- C. Use separate vessels (Correct Answer)
- D. Report to PHC if new symptoms arise
Explanation: ***Use separate vessels*** - **Tuberculosis** is primarily spread through airborne droplets, not through shared utensils. - While good hygiene is important, using separate dishes is not a specific requirement for preventing transmission in a household setting and is not routinely advised. *Collect drugs regularly* - **Regular collection and adherence to drug therapy** are crucial for treatment success and preventing drug resistance in tuberculosis. - Interrupted treatment can lead to **treatment failure** and spread of the disease. *Dispose sputum safely* - **Sputum** from a person with active tuberculosis contains the bacteria and can be a source of airborne transmission. - Proper disposal, such as in a covered container that is then sterilized or discarded safely, helps prevent the spread of infection. *Report to PHC if new symptoms arise* - **Close monitoring** for new or worsening symptoms is essential to identify potential side effects of medication, treatment failure, or development of complications. - Reporting to a **Primary Health Centre (PHC)** ensures timely medical review and management.
Question 384: Zoonotic diseases are -
- A. Anthrax
- B. Plague
- C. Salmonellosis
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Anthrax**, **Plague**, and **Salmonellosis** are all well-established examples of zoonotic diseases, which are infections naturally transmitted between vertebrate animals and humans. - These diseases represent a diverse spectrum of bacterial infections with significant public health implications worldwide. **Anthrax** - Caused by *Bacillus anthracis*, a spore-forming bacterium naturally found in soil that primarily affects livestock and wild herbivores. - Humans acquire infection through contact with infected animals or contaminated animal products (hides, wool, meat). - Clinical forms include cutaneous (most common), inhalational (most severe), and gastrointestinal anthrax. - Remains an important occupational hazard for veterinarians, farmers, and those handling animal products. **Plague** - Caused by *Yersinia pestis*, maintained in nature through rodent-flea cycles. - Transmission to humans occurs primarily via bites from infected fleas or direct contact with infected animals. - Historically responsible for devastating pandemics including the Black Death. - Clinical manifestations include bubonic (most common), pneumonic (person-to-person transmission possible), and septicemic plague. **Salmonellosis** - Caused by non-typhoidal *Salmonella* species, commonly colonizing the intestines of various animals including poultry, cattle, reptiles, and pets. - Humans typically acquire infection through consumption of contaminated food (undercooked meat, eggs, unpasteurized dairy) or direct animal contact. - Presents as acute gastroenteritis with diarrhea, fever, and abdominal cramps. - One of the most common foodborne zoonotic infections globally.
Question 385: Which of the following is NOT true about varicella infection?
- A. Lesions occur on flexor surfaces
- B. Secondary attack rate is 90%
- C. Only single stage of lesion is present at a time (Correct Answer)
- D. Reactivation occurs in 10-30% of cases
Explanation: ***Only single stage of lesion is present at a time*** - This statement is **incorrect** and represents the key distinguishing feature that makes this the answer. - Varicella (chickenpox) is classically characterized by **pleomorphism** - lesions in various stages of development (macules, papules, vesicles, pustules, and crusts) appearing **simultaneously** on the body. - This "multiple stages at once" phenomenon is a pathognomonic diagnostic feature of chickenpox, differentiating it from other vesicular rashes like smallpox (which shows uniform stage lesions). *Lesions occur on flexor surfaces* - This statement is **not a defining characteristic** of varicella, though it is not entirely false either. - Varicella typically has a **centripetal distribution** - lesions predominantly affect the **trunk and face**, with relative sparing of distal extremities. - Unlike conditions such as atopic dermatitis, varicella does **not** have a specific predilection for flexor versus extensor surfaces. - While lesions may appear on flexor areas, they appear throughout the body without preferential flexor involvement, making this statement less accurate than the other options. *Secondary attack rate is 90%* - This statement is **true**. Varicella is highly contagious with an R₀ (basic reproduction number) of 10-12. - The **secondary attack rate** among susceptible household contacts ranges from **80-90%**, making it one of the most contagious viral infections. *Reactivation occurs in 10-30% of cases* - This statement is **true**. After primary varicella infection, varicella-zoster virus (VZV) remains **latent in dorsal root ganglia**. - **Lifetime risk** of reactivation causing **herpes zoster (shingles)** is approximately **10-30%**, increasing with age and immunosuppression.
Question 386: Chance of acquiring Hepatitis B infection by eye splash with Hepatitis B positive patient blood:
- A. 10%
- B. 0.30% (Correct Answer)
- C. 20%
- D. 30%
Explanation: ***0.30%*** - The chance of acquiring **Hepatitis B infection** via an **eye splash (mucous membrane exposure)** from HBV-positive blood is approximately **0.3%**. - This risk is significantly lower than that following **percutaneous injury** (e.g., needlestick), which ranges from **6-30%** depending on the viral load and HBeAg status. - **Post-exposure prophylaxis (PEP)** with hepatitis B immunoglobulin (HBIG) and vaccination is recommended following such exposures. *10%* - This risk is **higher than the actual rate** for mucous membrane exposure to HBV. - A 10% transmission risk is closer to the **lower-to-mid range for percutaneous exposure** (needlestick injury), not mucosal exposure. *20%* - This percentage represents a risk **much higher** than that associated with mucous membrane exposure to Hepatitis B contaminated blood. - The 20% mark falls within the **mid-range for percutaneous exposure** from an HBeAg-positive source, not an eye splash. *30%* - This represents the **highest estimated risk** for Hepatitis B transmission through **percutaneous injury** (deep needlestick from HBeAg-positive patient with high viral load). - This is a significant **overestimation for eye splash (mucous membrane exposure)**, which carries approximately 100 times lower risk.
Question 387: According to WHO guidelines, the minimum recommended denier count for polyethylene mosquito nets (LLINs) for effective malaria prevention is:
- A. 250 denier
- B. 350 denier
- C. 100 denier
- D. 150 denier (Correct Answer)
Explanation: ***150*** - The World Health Organization (WHO) recommends a minimum of **150 denier polyethylene** or **75 denier polyester** for long-lasting insecticidal nets (LLINs) to ensure durability and effectiveness. - This denier count provides the necessary strength to withstand household conditions and repeated washing over several years without compromising the net's ability to prevent mosquito bites. *250* - While a denier count of **250** would generally indicate a thicker and potentially more durable fabric, it is not the *minimum recommended* by the WHO for effective malaria prevention using LLINs. - Such a high denier count might make the net heavier, more expensive, and potentially reduce breathability without offering significantly greater, WHO-mandated protective benefits over the recommended standard. *350* - A denier count of **350** would result in a very thick and heavy net material, which is well above the minimum recommendation for insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) by the WHO. - While it would be durable, it is not the **most important characteristic** in terms of meeting the fundamental effectiveness guidelines for malaria prevention and might lead to issues like increased cost, reduced airflow, and user discomfort. *100* - A denier count of **100** (for polyethylene) falls below the WHO's recommended minimum denier for long-lasting insecticidal nets (LLINs). - Nets with a lower denier count are generally **less durable** and more prone to tearing, which can compromise their effectiveness in preventing mosquito bites over their intended lifespan.
Question 388: Hepatitis B infection spreads through all of the following routes except
- A. Blood transfusion
- B. Sexual contact
- C. Perinatal transmission
- D. Fecal-oral route (Correct Answer)
Explanation: ***Fecal-oral route*** - **Hepatitis B** is primarily transmitted through contact with infected **blood** or **body fluids**, not via the fecal-oral route. - Diseases spread by the fecal-oral route are typically characterized by poor hygiene and contaminated food or water, which is not the case for Hepatitis B. *Blood transfusion* - Transmission through **blood transfusions** was a significant route before routine screening of blood products for **Hepatitis B surface antigen (HBsAg)** was implemented. - Although rare now in developed countries, it remains a possible route if unscreened blood is used. *Sexual contact* - **Hepatitis B virus (HBV)** is present in **semen** and **vaginal fluids**, making unprotected sexual intercourse a very common mode of transmission. - The risk of transmission increases with the number of partners and certain sexual practices. *Perinatal transmission* - **Perinatal transmission** from an infected mother to her newborn during **childbirth** is a major route of HBV spread, especially in endemic areas. - This can lead to chronic infection in infants if not prevented with immunoprophylaxis.
Question 389: Which one of the following is an emerging viral disease?
- A. SARS (Correct Answer)
- B. Measles
- C. Chicken pox
- D. Rabies
Explanation: ***SARS*** - **SARS (Severe Acute Respiratory Syndrome)** emerged in 2002-2003 and caused a global outbreak, making it a classic example of an **emerging viral disease**. - Emerging viral diseases are those that have recently appeared in a population or whose incidence has increased rapidly in recent times. *Measles* - Measles is an **established and re-emerging disease**, meaning it has been present for a long time but has seen resurgence due to factors like declining vaccination rates. - It is caused by the **measles virus (MeV)**, a paramyxovirus, and has been a known human pathogen for centuries. *Chicken pox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is a common and well-known childhood disease that has been endemic for a long time. - While it can be severe, it is not considered an emerging disease as its presence and characteristics have been established for many years. *Rabies* - Rabies, caused by the **rabies virus**, is a highly fatal disease primarily transmitted through animal bites and has been recognized globally for centuries. - Although it remains a significant public health concern, it is an **ancient and well-established zoonotic disease**, not an emerging one.
Question 390: A night blood survey is done in -
- A. Malaria
- B. Filariasis (Correct Answer)
- C. Dengue
- D. Plague
Explanation: ***Filariasis*** - A **night blood survey** is essential for diagnosing filariasis because **microfilariae**, especially *Wuchereria bancrofti* and *Brugia malayi*, exhibit **nocturnal periodicity**, meaning they are most abundant in peripheral blood at night. - This timing optimizes detection and confirms the presence of the parasitic worm larvae. *Malaria* - The diagnosis of malaria involves examining peripheral blood smears for **parasites (plasmodia)**, but screening is typically done at any time, especially during fever spikes. - Unlike filariasis, **malaria parasites** do not show a distinct nocturnal periodicity in the peripheral blood. *Dengue* - Dengue diagnosis relies on detecting the **virus (RNA)**, **viral antigens (NS1)**, or **antibodies (IgM, IgG)** in blood samples, which can be done at any time of the day. - It does not involve a "night blood survey" as the **dengue virus** is continuously present in the blood during the acute phase. *Plague* - Diagnosis of plague involves culturing the **bacterium *Yersinia pestis*** from blood, lymph node aspirates, or sputum, or detecting its antigens. - There is no specific requirement for a **night blood survey** as bacterial load does not exhibit nocturnal periodicity.
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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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