Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 611: Contact isolation is done for

A. Mumps
B. Asthma
C. Diphtheria
D. MRSA (Correct Answer)

Explanation: ***MRSA*** - **Methicillin-resistant *Staphylococcus aureus* (MRSA)** is transmitted primarily through direct contact with infected patients or contaminated surfaces, necessitating **contact isolation**. - **Contact precautions** involve the use of **gloves** and **gowns** when entering the patient's room to prevent transmission. *Mumps* - Mumps is a viral infection that is primarily transmitted via **respiratory droplets** produced during coughing, sneezing, or talking. - Patients with mumps typically require **droplet isolation**, not contact isolation, to prevent airborne transmission. *Diphtheria* - Diphtheria is a bacterial infection spread through **respiratory droplets** from the nose and throat of an infected person. - **Droplet precautions** are generally recommended for diphtheria, involving masks within a certain distance, rather than contact isolation. *Asthma* - **Asthma** is a chronic inflammatory condition of the airways and is not an infectious disease. - As asthma is not transmissible, it does **not require any form of isolation precautions** (contact, droplet, or airborne).

Question 612: Which of the following statements is incorrect regarding the strategic plan for malaria control 2012-2017?

A. 50% reduction in mortality by 2017
B. Objective is API < 1 per 10,000 (Correct Answer)
C. Complete treatment to 100% of patients
D. Annual incidence < 1 per 1000 by 2017

Explanation: ***Objective is API < 1 per 10,000*** - The correct objective for the **Annual Parasite Incidence (API)** in the 2012-2017 strategic plan for malaria control was to reduce it to **less than 1 per 1,000 population**, not 1 per 10,000, making this statement incorrect. - This metric measures the number of new malaria cases per 1,000 people per year. *50% reduction in mortality by 2017* - A key objective of the **National Framework for Malaria Elimination in India** (which this strategic plan aimed to contribute to) was indeed to achieve a significant reduction in malaria-related mortality. - Specifically, aiming for a **50% reduction in mortality** by 2017 was a stated goal to lessen the disease burden. *Annual incidence < 1 per 1000 by 2017* - One of the primary goals of the **Malaria Control Strategic Plan 2012-2017** was to reduce the annual parasite incidence (API) to **less than 1 per 1,000 population** in all endemic areas. - This target focused on decreasing the occurrence of new malaria cases. *Complete treatment to 100% of patients* - A core component of malaria control strategies emphasizes ensuring that **all confirmed malaria cases** receive complete and effective treatment. - Achieving **100% complete treatment adherence** is crucial to prevent drug resistance and eliminate the parasite reservoir.

Question 613: Most common route of nosocomial infection [Hospital-acquired infection]?

A. Droplet transmission
B. Direct contact (Correct Answer)
C. Indirect contact
D. Vehicle transmission

Explanation: **Direct contact** - **Direct contact** with colonized or infected patients is the predominant mode of transmission for many common nosocomial pathogens like **MRSA** and **VRE**. - This often involves healthcare workers' hands becoming contaminated and then touching other patients. *Droplet transmission* - Involves the transmission of infectious agents through **respiratory droplets** produced during coughing, sneezing, or talking. - While significant for some infections (e.g., influenza, pertussis), it is not the most common route overall for nosocomial infections. *Indirect contact* - Occurs when an infectious agent is transferred via a **contaminated intermediate object** or person. - Although important (e.g., contaminated medical devices), it is generally less frequent than direct patient-to-patient transmission. *Vehicle transmission* - Involves transmission through **contaminated inanimate vehicles** like food, water, medications, or surgical instruments. - While outbreaks can occur via this route (e.g., contaminated endoscopes), it is not the most common day-to-day transmission mechanism in hospitals.

Question 614: What is the most appropriate method for disinfecting urine specimens in clinical settings?

A. UV disinfection
B. Heat sterilization
C. Standard precautions (Correct Answer)
D. Chemical disinfection

Explanation: ***Standard precautions*** - **Standard precautions** are the appropriate method for handling urine specimens in clinical settings, treating all biological specimens as potentially infectious. - This includes use of **personal protective equipment (PPE)**, proper containment in leak-proof containers, and safe handling practices to protect laboratory personnel. - Importantly, the specimen itself is **NOT disinfected** before analysis, as this would destroy pathogens, cells, and other diagnostic elements that need to be identified. - Standard precautions prevent exposure while maintaining **specimen integrity** for accurate diagnostic testing including culture, microscopy, and biochemical analysis. *UV disinfection* - UV light would **kill bacteria** needed for urine culture and sensitivity testing, rendering the specimen useless for microbiological diagnosis. - It would also damage **cellular elements** (WBCs, RBCs, epithelial cells) required for microscopic examination. - UV disinfection has **no role** in routine clinical urine specimen processing for diagnostic purposes. *Chemical disinfection* - Chemical disinfectants would **destroy pathogens** that need to be isolated and identified in urine culture. - They would interfere with **all subsequent analyses** including biochemical tests, microscopy, and culture. - This method is inappropriate for specimens requiring diagnostic evaluation. *Heat sterilization* - Autoclaving would completely **destroy all diagnostic elements** including bacteria, cells, proteins, and other analytes. - Heat sterilization is used only for **disposal of biohazardous waste** after testing is complete, never for specimen preparation.

Question 615: Drug of choice for mass therapy under filariasis control programme?

A. Albendazole
B. Ivermectin
C. DEC (Correct Answer)
D. Mebendazole

Explanation: ***Correct: DEC*** - **Diethylcarbamazine (DEC)** is the drug of choice for **mass drug administration (MDA)** campaigns aimed at eliminating lymphatic filariasis. - It effectively kills **microfilariae** and has some action on adult worms, reducing transmission. - In India's National Filariasis Elimination Programme, DEC is administered along with Albendazole in annual MDA campaigns. *Incorrect: Albendazole* - While **Albendazole** is co-administered with DEC in MDA programs, it is not the sole drug of choice for mass treatment of filariasis. - Its primary role is to provide **macrofilaricidal** activity (killing adult worms) and co-treatment for other helminth infections. - It enhances the effect of DEC but is not used alone. *Incorrect: Ivermectin* - **Ivermectin** is used in MDA programs for filariasis, particularly in areas co-endemic with **onchocerciasis** or where **Loa loa** is prevalent (as DEC is contraindicated in these areas). - However, in India and most lymphatic filariasis endemic areas, **DEC** remains the primary drug. *Incorrect: Mebendazole* - **Mebendazole** is an anthelminthic primarily used for treating **intestinal nematode infections** like ascariasis, trichuriasis, and hookworm. - It is **not used** in lymphatic filariasis mass treatment programs.

Question 616: Which of the following is not a recognized transmission route for amoebiasis?

A. Sexual transmission
B. Blood and blood products
C. Vector transmission (Correct Answer)
D. Fecal-oral route

Explanation: ***Vector transmission*** - Amoebiasis, caused by *Entamoeba histolytica*, is primarily an **intestinal infection** transmitted through the **fecal-oral route**. - Its life cycle **does not involve any arthropod vector** (e.g., mosquito, tick, fly) for transmission. - This is the **only route among the options that is definitively NOT recognized** for amoebiasis transmission. *Sexual transmission* - Amoebiasis **can be transmitted** through **oral-anal sexual contact**, particularly documented in men who have sex with men (MSM). - This represents an **indirect fecal-oral transmission** route and is a recognized mode of spread. *Blood and blood products* - While *E. histolytica* can disseminate to cause **amoebic liver abscesses** and rarely systemic disease, transmission via blood transfusion is **extremely rare and not well-documented**. - However, theoretically possible in cases of parasitemia during invasive disease. - Unlike vector transmission, this cannot be definitively ruled out as "not recognized." *Fecal-oral route* - This is the **primary and most important transmission route** for amoebiasis. - Infection occurs through ingestion of **cysts** from contaminated food, water, or through direct person-to-person contact with poor hand hygiene.

Question 617: What is the most common mode of transmission of HIV?

A. Occupational exposure (needle stick injury)
B. Perinatal transmission (mother to child)
C. Sexual contact (Correct Answer)
D. Transmission via blood and blood products

Explanation: ***Sexual contact*** - **Unprotected sexual intercourse**, both heterosexual and homosexual, is overwhelmingly the most common way HIV is transmitted globally. - The virus can be exchanged through **bodily fluids** such as semen, vaginal fluids, and rectal fluids during sexual activity. - Accounts for approximately **80% of new HIV infections** worldwide. *Occupational exposure (needle stick injury)* - While a recognised mode of transmission, **needle stick injuries** account for a very small percentage of total HIV infections, primarily affecting healthcare workers. - The risk of transmission per exposure is relatively low (approximately **0.3%**), especially compared to sexual contact. *Perinatal transmission (mother to child)* - **Mother-to-child transmission** can occur during pregnancy, childbirth, or breastfeeding. - Although significant, especially in resource-limited settings, global efforts and **PMTCT programs** have resulted in a significant reduction in this type of transmission. *Transmission via blood and blood products* - This mode was once a major concern but is now extremely rare in countries with robust **blood screening programs**. - While sharing contaminated needles among **intravenous drug users** remains a risk, transfusion-related HIV is largely controlled.

Question 618: Which of the following is an example of indirect transmission by a living vector?

A. Transmission by mosquito (Correct Answer)
B. Vertical transmission
C. Soil contact
D. Droplet infection

Explanation: ***Transmission by mosquito*** - This is the classic example of **vector-borne transmission**, where a living biological vector (the mosquito) acts as an intermediary to transmit the infectious agent from an infected host to a susceptible one. - The disease-causing microorganism does not pass directly from person to person but is carried and transmitted by the living vector. - Examples include malaria, dengue, and filariasis. *Vertical transmission* - This refers to transmission of disease from a **mother to her child** during pregnancy, childbirth, or breastfeeding. - This is a form of **direct transmission** where the pathogen passes directly between biologically related individuals without an intermediate living vector. *Soil contact* - This represents **vehicle-borne transmission** where soil acts as a non-living vehicle (fomite) carrying pathogens. - While this is technically indirect transmission, it does not involve a **living biological vector** as specified in the question. - Examples include tetanus, hookworm, and ascariasis transmitted through contaminated soil. *Droplet infection* - This is a form of **direct transmission** where infectious droplets are expelled from the respiratory tract of an infected person and directly contact the mucous membranes of a susceptible person. - The droplets travel a short distance in close proximity, representing direct person-to-person transfer without any intermediate vector.

Question 619: Reservoir of infection in enteric fever?

A. Birds
B. Cow
C. Man (Correct Answer)
D. Water

Explanation: ***Man*** - Humans are the **sole natural reservoir** for *Salmonella Typhi* and *Salmonella Paratyphi*, the causative agents of enteric fever (typhoid and paratyphoid fever). - The bacteria can persist in the **gallbladder** of asymptomatic carriers, who can then shed the bacteria in their feces, contributing to transmission. *Birds* - Birds are not considered a primary reservoir for the **causative pathogens of enteric fever** (*Salmonella Typhi* or *Paratyphi*). - They are more commonly associated with other *Salmonella* serotypes, such as *Salmonella Enteritidis*, which cause **gastroenteritis** rather than systemic enteric fever. *Cow* - Cows are not a primary reservoir for the organisms responsible for **enteric fever**; these pathogens are specifically adapted to humans. - While cows can carry various *Salmonella* species, they are typically associated with **foodborne outbreaks** of *Salmonella*-induced **gastroenteritis**, not typhoid fever. *Water* - Water is a **vehicle for transmission** of enteric fever, becoming contaminated with human feces containing *Salmonella Typhi* or *Paratyphi*. - It is not a reservoir because the bacteria do not naturally **multiply or persist indefinitely** in water without a human source.

Question 620: Which of the following screening methods is primarily used under the National Tuberculosis Elimination Program (NTEP)?

A. Active
B. Passive (Correct Answer)
C. Mass
D. None of the options

Explanation: ***Passive*** - Under the NTEP, **passive screening** involves individuals presenting to health facilities with symptoms suggestive of TB. - This method relies on **patient self-reporting** and healthcare provider suspicion, rather than active outreach. - Passive case finding is the **primary screening strategy** used across the general population in the NTEP framework. *Active* - **Active screening** involves community-based interventions to proactively identify individuals with TB, often in high-risk populations. - While active case finding is crucial for specific vulnerable groups (contacts, HIV patients, etc.), it is **not the primary screening method** under the standard NTEP framework for initial detection across the entire population. *Mass* - **Mass screening** involves testing large numbers of people in the general population, regardless of symptoms, to detect disease. - This is generally **cost-prohibitive** and not routinely implemented as a primary screening strategy for TB by the NTEP due to resource limitations and low yield in the general population. *None of the options* - **Passive screening** is indeed a primary method used under the NTEP, making this option incorrect. - The NTEP heavily relies on individuals seeking care when they experience symptoms, which aligns with the definition of passive case finding.

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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