Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 431: Which microorganism is considered the MOST significant agent for use as a weapon in biological terrorism?

A. Smallpox (Correct Answer)
B. Influenza
C. Ebola
D. Rabies

Explanation: ***Smallpox*** - **Smallpox** is considered a high-priority biological weapon agent due to its **high infectivity**, person-to-person transmission, and high mortality rate. - The discontinuation of global vaccination has led to a population with **minimal immunity**, making it a potent bioweapon. *Influenza* - While influenza viruses are highly transmissible and can cause significant illness, their **mortality rate is generally lower** than agents specifically chosen for biological warfare. - Widespread immunity from natural exposure and annual vaccination campaigns limits its effectiveness as a primary bioweapon. *Ebola* - **Ebola virus** causes severe hemorrhagic fever with a high fatality rate but is typically **less easily transmitted** than agents like smallpox through airborne routes. - Its outbreaks are usually localized, and containment measures are effective in preventing widespread pandemic spread, making it less ideal for mass casualty scenarios compared to smallpox. *Rabies* - **Rabies virus** is transmitted primarily through the bite of an infected animal and is **not easily spread from person to person**. - Its **incubation period is long**, and post-exposure prophylaxis is highly effective, making it an impractical agent for widespread biological terrorism.

Question 432: "White plague" is

A. Pneumonic Plague
B. Leprosy
C. Tuberculosis (Correct Answer)
D. Bubonic Plague

Explanation: ***Tuberculosis*** - This term was historically used for **tuberculosis** due to the characteristic **pallor** and wasting often seen in patients with advanced disease. - It also refers to the widespread and devastating nature of the disease, similar to a "plague," but referring to the chronic emaciation and pale appearance. *Pneumonic Plague* - This is a severe form of **plague** that affects the lungs and is characterized by **rapidly progressing pneumonia**, cough, and shortness of breath. - It does not cause the characteristic pallor or chronic wasting implied by "white plague." *Leprosy* - This is a chronic infectious disease primarily affecting the **skin**, nerves, upper respiratory tract, eyes, and testes. - While it can cause skin lesions and deformities, the term "white plague" is not traditionally associated with leprosy. *Bubonic Plague* - This is the most common form of plague, characterized by **swollen, painful lymph nodes** called "buboes." - It is known for its high mortality rate but does not directly cause the "white" appearance or chronic wasting implied by the term "white plague."

Question 433: FALSE about Leprosy eradication programme is ?

A. Disability limitation
B. Health education
C. Long term multi drug therapy (Correct Answer)
D. Early detection of cases

Explanation: ***Long term multi drug therapy*** - Leprosy eradication programs emphasize **short-term, highly effective multi-drug therapy (MDT)**, not long-term. - The standard duration for paucibacillary leprosy is 6 months and for multibacillary leprosy is 12 months, which is considered short-term given the chronic nature of the disease. *Disability limitation* - This is a crucial component of leprosy programs, focusing on preventing and managing **nerve damage** and its consequences. - Interventions include **early detection of nerve impairment**, protective footwear, and physio-occupational therapy to minimize permanent disabilities. *Health education* - **Health education** is essential for successful eradication, as it increases public awareness, reduces stigma, and promotes early reporting of symptoms. - It also educates patients on the importance of **adherence to MDT** and self-care practices. *Early detection of cases* - **Early detection and prompt treatment** of leprosy cases are fundamental to preventing transmission and reducing the burden of the disease. - This helps to interrupt the chain of infection and prevent the development of severe disabilities.

Question 434: National AIDS Control Programme was started in:

A. 1985
B. 1984
C. 1987 (Correct Answer)
D. 1986

Explanation: ***Correct Option: 1987*** - The National AIDS Control Programme (NACP) in India was officially initiated in **1987** - Its objective was to prevent the transmission of **HIV** and manage the care of people living with **AIDS** - This was launched in response to the detection of the first HIV cases in India in 1986 *Incorrect Option: 1986* - The first case of **HIV** in India was detected in **1986** in Chennai among sex workers - While this discovery was pivotal, it prompted the establishment of NACP, which officially began the following year in 1987 - This marks the recognition phase rather than the program launch *Incorrect Option: 1985* - While significant early efforts against **HIV/AIDS** were underway globally around this time, NACP was not formally launched in India until later - The initial **HIV case** in India was identified in 1986, making a 1985 program launch chronologically impossible *Incorrect Option: 1984* - In 1984, the global understanding of **HIV/AIDS** was still rapidly evolving - Comprehensive national programs like NACP were not yet established in India - This period predates the official recognition of **HIV** as a major public health concern in the country

Question 435: A 10-year-old boy with dog bite unprovoked comes to you. Appropriate action is:

A. No further action is necessary
B. Give cell culture derived vaccine and rabies immunoglobulin (Correct Answer)
C. Kill dog and send brain for biopsy
D. Withhold vaccine and observe dog for 10 days

Explanation: ***Give cell culture derived vaccine and rabies immunoglobulin*** - An **unprovoked dog bite** carries a high risk of **rabies transmission**, especially in a 10-year-old boy. The most appropriate action is immediate **post-exposure prophylaxis (PEP)**. - **PEP for Category III exposures** (transdermal bites) involves administering a **cell culture-derived rabies vaccine** series along with **rabies immunoglobulin** (RIG) infiltrated into and around the wound, to provide both active and passive immunity. *No further action is necessary* - This option is incorrect and dangerous as **rabies is a fatal disease** once symptoms appear. - An **unprovoked bite** indicates a high suspicion of the dog being rabid, necessitating urgent intervention. *Kill dog and send brain for biopsy* - While testing the animal's brain for rabies is helpful for confirmation, it should **not delay immediate human PEP**, which is critical for survival. - The dog's temperament or rabies status may not be immediately ascertainable, making PEP the priority. *Withhold vaccine and observe dog for 10 days* - Observing the dog for 10 days is a protocol for **low-risk bites from proven healthy dogs that are traceable**, e.g., a pet with known vaccination history. - In cases of **unprovoked bites**, especially from a stray or unknown animal, immediate PEP is mandatory due to the fatal nature of rabies and the unreliability of the observation period in such scenarios.

Question 436: Sputum examination for AFB is a type of

A. Tertiary prevention
B. Primordial prevention
C. Secondary prevention (Correct Answer)
D. Primary prevention

Explanation: ***Secondary prevention*** - **Sputum examination for AFB** (acid-fast bacilli) aims for **early diagnosis** and **prompt treatment** of tuberculosis. - This level of prevention focuses on **halting the progression of a disease** that has already occurred or reducing its severity. *Tertiary prevention* - This level of prevention involves **rehabilitation** and preventing complications in individuals with **established disease**. - Examples include physical therapy after a stroke or managing chronic conditions to improve quality of life. *Primordial prevention* - This stage of prevention focuses on **preventing the emergence of risk factors** in the first place, often by addressing broad socioeconomic and environmental determinants. - It targets the entire population and is concerned with **social and environmental conditions** that contribute to risk factors. *Primary prevention* - This level of prevention aims to **prevent the onset of disease** by reducing exposure to risk factors or increasing resistance to disease. - Examples include **vaccination**, health education, and promoting healthy lifestyles to **prevent initial disease occurrence**.

Question 437: Which of the following statements regarding classical Dengue fever is FALSE?

A. Positive tourniquet test (Correct Answer)
B. Low case fatality rate
C. Self limiting disease
D. Transmitted by Aedes aegypti

Explanation: **CRITICAL ISSUE:** This question as currently written is problematic because **all four statements are TRUE** about classical dengue fever, making it impossible to identify a FALSE statement. ***Analysis of Each Statement:*** **Positive tourniquet test** (Currently marked as answer) - This is actually a **TRUE statement** about classical dengue fever - The tourniquet test is **positive in classical dengue fever** and is used as a diagnostic criterion by WHO - A positive tourniquet test indicates capillary fragility and is seen in both classical dengue and DHF - **This should NOT be the answer** to a FALSE question **Low case fatality rate** - TRUE statement: Classical dengue fever has a very low case fatality rate (<1%) with proper supportive care - Mortality is primarily associated with severe dengue/DHF/DSS **Self limiting disease** - TRUE statement: Classical dengue is typically self-limiting, resolving within 7-10 days with symptomatic treatment - Characterized by fever, headache, retro-orbital pain, myalgia, and rash **Transmitted by Aedes aegypti** - TRUE statement: **Aedes aegypti** is the primary vector for dengue transmission - Also transmitted by Aedes albopictus in some regions - Day-biting mosquitoes found in urban/semi-urban areas **RECOMMENDATION:** This question needs revision as it currently has no correct answer. All options are true statements about classical dengue fever.

Question 438: Which disease is highly transmitted during the incubation period?

A. Pertussis
B. Brucellosis
C. Cholera
D. Measles (Correct Answer)

Explanation: ***Measles*** - Measles is **highly transmissible during the late incubation period**, starting approximately **4 days before the rash appears**. - The incubation period is 10-14 days from exposure to rash onset, and viral shedding begins in the **last few days of incubation** even before symptoms develop. - Patients remain contagious through the **prodromal phase** (fever, cough, coryza, conjunctivitis) and up to 4 days after rash onset, making it one of the most contagious diseases with **significant pre-symptomatic transmission**. - This characteristic makes measles difficult to control as infected individuals unknowingly spread the virus before diagnosis. *Pertussis* - While pertussis is highly contagious, peak transmission occurs during the **catarrhal stage**, which is the **first clinical stage after incubation ends**, not during the incubation period itself. - The incubation period (7-10 days) is relatively **non-infectious**, with bacterial shedding peaking once symptoms (mild cold-like symptoms) appear. - Maximum contagiousness occurs during the catarrhal and early paroxysmal stages when symptoms are present. *Brucellosis* - **Brucellosis** is primarily transmitted through direct contact with infected animals or consumption of unpasteurized dairy products. - **Human-to-human transmission is extremely rare**, making transmission during the incubation period clinically insignificant. - It does not fit the pattern of respiratory droplet or direct person-to-person spread during incubation. *Cholera* - **Cholera** transmission occurs mainly through the **fecal-oral route** via contaminated water or food. - Maximum infectivity occurs during the **symptomatic phase** when large volumes of bacteria-laden stool are passed. - During the short incubation period (few hours to 5 days), bacterial shedding is minimal and transmission risk is low compared to the symptomatic phase.

Question 439: Which of the following is the most common vector of zoonotic diseases?

A. Sand fly
B. Ticks
C. Mosquito (Correct Answer)
D. Mite

Explanation: ***Mosquito*** - Mosquitoes are responsible for transmitting a vast number of **zoonotic diseases** affecting millions globally, including **malaria**, dengue, Zika, and **West Nile virus**. - Their widespread distribution and ability to feed on various hosts, including humans and animals, make them highly efficient **vectors**. *Sand fly* - Sand flies are known vectors for diseases like **leishmaniasis**, but their reach and impact are not as extensive as mosquitoes. - Leishmaniasis primarily affects specific geographic regions and isn't as globally prevalent as mosquito-borne illnesses. *Ticks* - Ticks transmit several important zoonotic diseases such as **Lyme disease**, Rocky Mountain spotted fever, and ehrlichiosis. - While significant, the global burden of tick-borne diseases is generally less than that of mosquito-borne diseases. *Mite* - Mites can transmit diseases like **scrub typhus** (via chiggers) and are associated with scabies, which is an infestation rather than a direct disease transmission. - Their role as vectors for major zoonotic diseases is comparatively limited.

Question 440: Hand, foot, and mouth disease is characterized by

A. Incubation period of 3-10 days
B. Cause miniepidemic in school
C. Transmitted by virus (Correct Answer)
D. Clinical features similar to those seen in cows

Explanation: ***Transmitted by virus*** - **Hand, foot, and mouth disease (HFMD)** is caused by **enteroviruses**, most commonly Coxsackievirus A16 and enterovirus 71. - These viruses spread readily through **direct contact** with an infected person's nose and throat secretions, blister fluid, or feces. - This is the **most fundamental characteristic** of the disease - its viral etiology. *Incubation period of 3-10 days* - The typical incubation period for HFMD is usually **3 to 7 days**, from exposure to the onset of symptoms. - While 3-10 days is technically accurate as a broader range, it is **not the most defining characteristic** of the disease. *Cause miniepidemic in school* - HFMD is highly contagious and commonly causes **localized outbreaks or "mini-epidemics"** in settings where young children gather, such as schools and daycare centers. - This is a true characteristic of the disease but is **not the most fundamental defining feature** like its viral etiology. *Clinical features similar to those seen in cows* - While there is a disease called "foot-and-mouth disease" in animals (primarily cows, sheep, and pigs), it is caused by a **completely different virus** (an Aphthovirus) and **does not affect humans**. - **Hand, foot, and mouth disease in humans** is entirely distinct and has **no relationship** to the animal disease despite the similar name.

Practice by Chapter

Communicable Disease Control Principles

Practice Questions

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

Practice Questions

HIV/AIDS Control Program

Practice Questions

Tuberculosis Control

Practice Questions

Leprosy Elimination

Practice Questions

Emerging and Re-emerging Infections

Practice Questions

Hospital-Acquired Infections

Practice Questions

Integrated Disease Surveillance Project

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