Infectious Diseases — MCQs
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What is the most appropriate method for disinfecting urine specimens in clinical settings?
Most common route of nosocomial infection [Hospital-acquired infection]?
Behavioral surveillance survey is done in?
What is a major sign for AIDS surveillance in the WHO case definition?
What is the most common Anopheles mosquito responsible for malaria in India?
In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?
All are features of yellow fever except?
What is the annual infection rate of tuberculosis?
Which of the following statements best describes the operational definition of onchocerciasis elimination?
Which of the following IS included in the NVBDCP?
Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 631: 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 632: 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 633: Behavioral surveillance survey is done in?
- A. AIDS (Correct Answer)
- B. TB
- C. Filaria
- D. Malaria
Explanation: ***AIDS*** - Behavioral surveillance surveys are crucial for understanding and monitoring behaviors related to **HIV transmission**, such as sexual practices and drug use, among at-risk populations. - These surveys help in designing and evaluating **prevention programs** by identifying trends in risky behaviors and knowledge, attitudes, and practices (KAP) concerning HIV. *Filaria* - Surveillance for filaria primarily involves **entomological surveys** (mosquito monitoring) and **parasitological surveys** (blood examinations for microfilariae). - Behavioral aspects are less central to direct surveillance compared to disease vectors and infection rates. *TB* - Tuberculosis surveillance mainly focuses on **case detection**, **treatment outcomes**, and monitoring **drug resistance** through clinical and laboratory data. - While patient adherence to treatment involves behavior, there isn't a dedicated "behavioral surveillance survey" method specifically for TB. *Malaria* - Malaria surveillance involves monitoring **parasitemia rates**, **vector populations**, and **antimalarial drug resistance**. - Behavioral components like bed net usage are important, but the primary surveillance methods are not termed "behavioral surveillance surveys" in the same structured way as for HIV.
Question 634: What is a major sign for AIDS surveillance in the WHO case definition?
- A. Weight loss greater than 10% (Correct Answer)
- B. Chronic cough for more than 1 month
- C. Generalized lymphadenopathy
- D. Disseminated herpes infection
Explanation: ***Weight loss greater than 10%*** - **Weight loss >10% of body weight** is one of the **three major signs** in the WHO clinical case definition for AIDS surveillance. - The **three major signs** are: (1) Weight loss >10%, (2) Chronic diarrhea >1 month, and (3) Prolonged fever >1 month. - This symptom reflects **"wasting syndrome,"** a severe manifestation of advanced HIV disease indicating significant metabolic and immunological dysfunction. - Major signs are critical for AIDS surveillance, especially in resource-limited settings where laboratory diagnosis may not be readily available. *Chronic cough for more than 1 month* - This is classified as a **minor sign**, not a major sign, in the WHO AIDS surveillance definition. - While chronic cough can indicate opportunistic infections like tuberculosis or *Pneumocystis jirovecii* pneumonia in HIV-infected individuals, it does not meet the criteria for a major sign. - WHO clinical staging requires major signs to have greater specificity for advanced disease. *Generalized lymphadenopathy* - **Generalized lymphadenopathy** is a **minor sign** in the WHO case definition. - Also known as Persistent Generalized Lymphadenopathy (PGL), it is common in early to chronic HIV infection but does not typically signify AIDS-stage disease. - It involves lymph node enlargement in two or more non-contiguous sites (excluding inguinal nodes) for more than 3 months. *Disseminated herpes infection* - Chronic progressive or disseminated herpes simplex infection is classified as a **minor sign**, not a major sign. - While severe herpes infections (including recurrent herpes zoster) are associated with immunosuppression in HIV, they are part of the minor criteria in WHO AIDS surveillance. - Major signs are reserved for more specific indicators of severe immunodeficiency and wasting.
Question 635: What is the most common Anopheles mosquito responsible for malaria in India?
- A. Anopheles stephensi
- B. Anopheles subpictus
- C. Anopheles culicifacies (Correct Answer)
- D. Anopheles fluviatilis
Explanation: ***Anopheles culicifacies*** - This species is the **most common and primary malaria vector in India**, responsible for approximately 60-70% of all malaria transmission in the country. - It is the **major rural vector** of malaria, especially in agricultural areas, and transmits both *Plasmodium vivax* and *P. falciparum*. - Given that the majority of India's population resides in rural areas where malaria burden is highest, *A. culicifacies* is the most important vector overall. *Anopheles stephensi* - This species is recognized as the **primary urban vector** of malaria in India, particularly for *P. vivax* and *P. falciparum*. - Its ability to breed in artificial containers makes it well-adapted to urban environments, but it accounts for a smaller proportion of total malaria cases compared to *A. culicifacies*. *Anopheles fluviatilis* - This species is an **important vector in hilly and forest areas** of India, rather than being the most common overall. - It is known to transmit both *P. vivax* and *P. falciparum* in these specific ecological niches. *Anopheles subpictus* - While present in India, *A. subpictus* is generally considered a **poor vector** of malaria due to its low susceptibility to Plasmodium infection. - It mainly breeds in diverse habitats including paddy fields and brackish water.
Question 636: In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?
- A. 3 months
- B. 6 months
- C. 1 year (Correct Answer)
- D. 3 years
Explanation: **1 year** - A person is defined as a permanent carrier of typhoid if they excrete **Salmonella Typhi** in their feces or urine for **more than one year** after the acute illness. - This long-term excretion is often associated with chronic infection of the **gallbladder**, particularly in individuals with gallstones. - The definition of chronic/permanent carrier status is set at **≥12 months** of continuous bacillary excretion. *3 months* - Excreting bacilli for 3 months after acute typhoid is considered a **convalescent carrier state**, not a permanent one. - Many individuals clear the infection within this timeframe without becoming chronic carriers. *6 months* - While prolonged, 6 months of excretion still falls under the definition of a **convalescent or temporary carrier**, rather than a permanent carrier. - The threshold for "permanent" or "chronic" carrier status is typically set at 12 months. *3 years* - While a person excreting bacilli for 3 years would certainly be a permanent carrier, the established definition for permanent carrier status is met at **1 year**, not 3 years. - This option represents an unnecessarily longer duration than the standard definition.
Question 637: All are features of yellow fever except?
- A. Caused by vector aedes
- B. IP 3-6 days
- C. 1 attack gives life long immunity
- D. Validity of vaccination begins immediately after vaccination (Correct Answer)
Explanation: ***Validity of vaccination begins immediately after vaccination*** - Yellow fever vaccine is highly effective, but **immunity does not develop immediately**; it typically offers protection starting **10 days after vaccination**. - This delay is crucial for travelers to endemic areas, as they need to be vaccinated well in advance to ensure protection. *IP 3-6 days* - The **incubation period (IP)** for yellow fever is indeed short, usually ranging from **3 to 6 days** after the bite of an infected mosquito. - This brief incubation period contributes to the rapid onset of symptoms once infected. *1 attack gives life long immunity* - Similar to many viral infections, a single bout of yellow fever infection generally provides **lifelong immunity** against future infections. - This is why the vaccine is so effective, as it mimics natural infection to induce comprehensive, long-term protection. *Caused by vector aedes* - Yellow fever is transmitted primarily by **Aedes mosquitoes**, particularly **Aedes aegypti**, which are responsible for urban and jungle cycles of transmission. - These mosquitoes are prevalent in tropical and subtropical regions of Africa and South America.
Question 638: What is the annual infection rate of tuberculosis?
- A. Percentage of total patients positive for tuberculin test
- B. Percentage of new patients positive for tuberculin test (Correct Answer)
- C. Percentage of sputum positive total patients
- D. Percentage of sputum positive new patients
Explanation: ***Percentage of new patients positive for tuberculin test*** - The **annual infection rate of tuberculosis (AIRT)** is defined as the percentage of individuals (typically children aged 1-9 years) who show **tuberculin conversion** (from negative to positive) in a given year. - Among the given options, this is the **closest representation** as it focuses on **newly infected individuals** rather than prevalent cases. - AIRT is a key epidemiological indicator reflecting **ongoing transmission** and the **annual risk of tuberculous infection** in a community. - This measure helps assess TB control program effectiveness and disease burden. *Percentage of total patients positive for tuberculin test* - This represents the **prevalence of tuberculosis infection** in the population, including both old and new infections. - It does not specifically measure the **annual rate of acquiring new infections**, which is what AIRT captures. *Percentage of sputum positive total patients* - This indicates the **prevalence of active, infectious pulmonary tuberculosis** in a population. - It refers to individuals with **active TB disease** who are shedding bacteria in sputum, not latent infection detected by tuberculin testing. *Percentage of sputum positive new patients* - This represents the **incidence of new, active, infectious tuberculosis cases** (case detection rate). - While important for TB surveillance, it measures **active disease** rather than **infection rate** detected by tuberculin skin test.
Question 639: Which of the following statements best describes the operational definition of onchocerciasis elimination?
- A. All interventions have been successfully implemented.
- B. There is no recrudescence of the disease after a defined period.
- C. All of the options are true.
- D. Transmission of O. volvulus has been reduced to a level where it cannot sustain itself in the population. (Correct Answer)
Explanation: **Transmission of O. volvulus has been reduced to a level where it cannot sustain itself in the population.** - This statement accurately reflects the definition of **disease elimination**, where the incidence of infection is reduced to zero in a defined geographical area, signifying that the **transmission cycle can no longer be sustained**. - For onchocerciasis, this means the **vector (blackfly)** is no longer transmitting the parasite (*Onchocerca volvulus*) between humans at a rate that allows the disease to persist. *All interventions have been successfully implemented.* - While successful implementation of interventions is crucial for elimination, it is a **process goal**, not the **ultimate outcome** or operational definition of elimination itself. - Elimination is defined by the **absence of sustained transmission**, which is a direct measure of disease burden, not intervention fidelity. *There is no recrudescence of the disease after a defined period.* - The **absence of recrudescence** (re-emergence) after a defined period is an important indicator of successful elimination validation, but it is a **consequence** or **part of the verification process**, not the primary operational definition. - The operational definition focuses on the **state of transmission** that leads to this sustained absence. *All of the options are true.* - This option is incorrect because only one of the provided statements accurately describes the **operational definition of elimination** in the context of parasitic diseases like onchocerciasis. - The other options describe aspects related to the elimination process or its verification, but not the core definition.
Question 640: Which of the following IS included in the NVBDCP?
- A. Leprosy
- B. Malaria
- C. Dengue
- D. Chikungunya (Correct Answer)
Explanation: ***Chikungunya*** - **Chikungunya** is one of the six diseases covered under the **National Vector Borne Disease Control Programme (NVBDCP)** in India. - The NVBDCP specifically includes: **Malaria, Dengue, Chikungunya, Lymphatic Filariasis, Kala-azar (Visceral Leishmaniasis), and Japanese Encephalitis**. - Chikungunya, transmitted by *Aedes* mosquitoes, represents a significant public health concern requiring vector control measures. *Leprosy* - **Leprosy** is NOT covered under NVBDCP as it is **not a vector-borne disease**. - Leprosy is caused by *Mycobacterium leprae* and spreads through prolonged close contact with infected individuals, not through vectors. - It is managed under a separate program: **National Leprosy Eradication Programme (NLEP)**. *Malaria* - **Malaria** is indeed included in NVBDCP and is actually the **primary focus** of the program. - However, since the question asks for which disease IS included and all vector-borne options would be correct, the presence of Leprosy as a distractor makes Chikungunya the correct choice among valid NVBDCP diseases. *Dengue* - **Dengue** is also covered under NVBDCP as one of the six priority vector-borne diseases. - Like Malaria and Chikungunya, Dengue receives focused surveillance and control interventions under this national program.
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Communicable Disease Control Principles
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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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