Infectious Diseases Practice Questions

Q: Among the following options, the minimum acceptable Rideal-Walker coefficient for disinfectant used for cholera stool would be?

2. ***2 (Minimum acceptable among given options)*** - The **Rideal-Walker coefficient** measures disinfectant efficacy relative to phenol as the standard reference - A coefficient of **2** means the disinfectant is **twice as effective** as phenol against test organisms (*Salmonella typhi* and *Staphylococcus aureus*) - While higher coefficients are preferred for highly infectious materials like cholera stool, **2 represents the minimum acceptable threshold** among the given options that still provides reasonable disinfection efficacy - Standard practice recommends disinfectants with RW coefficient ≥5 for cholera stool, but among the choices provided, 2 is the lowest that meets basic acceptability criteria *4 (Better choice but not the minimum)* - A coefficient of **4** means the disinfectant is **four times more effective** than phenol - This provides **more robust disinfection** and would be preferred over a coefficient of 2 - However, the question specifically asks for the **minimum acceptable** value, not the optimal value - Among the options, this is not the minimum *7 (Highly effective)* - A coefficient of **7** indicates the disinfectant is **seven times more potent** than phenol - This represents **very good disinfection efficacy** and exceeds minimum requirements - This is well above the minimum acceptable threshold *10 (Excellent efficacy)* - A coefficient of **10** means the disinfectant is **ten times more effective** than phenol - This represents **excellent disinfection power** with a very high safety margin - While ideal for high-risk situations, this far exceeds the minimum acceptable requirement

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

Standard precautions. ***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.

Q: Behavioral surveillance survey is done in?

AIDS. ***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.

Q: What is a major sign for AIDS surveillance in the WHO case definition?

Weight loss greater than 10%. ***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.

Q: What is the most common Anopheles mosquito responsible for malaria in India?

Anopheles culicifacies. ***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.

Q: In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?

1 year. **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.

Q: What is the annual infection rate of tuberculosis?

Percentage of new patients positive for tuberculin test. ***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.

Q: Which of the following IS included in the NVBDCP?

Chikungunya. ***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.

Question 1

Among the following options, the minimum acceptable Rideal-Walker coefficient for disinfectant used for cholera stool would be?

Accepted Answer

2

Answer

4

Answer

10

Answer

7

Question 2

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

Accepted Answer

Standard precautions

Answer

UV disinfection

Answer

Heat sterilization

Answer

Chemical disinfection

Question 3

Behavioral surveillance survey is done in?

Accepted Answer

AIDS

Answer

TB

Answer

Filaria

Answer

Malaria

Question 4

What is a major sign for AIDS surveillance in the WHO case definition?

Accepted Answer

Weight loss greater than 10%

Answer

Chronic cough for more than 1 month

Answer

Generalized lymphadenopathy

Answer

Disseminated herpes infection

Question 5

What is the most common Anopheles mosquito responsible for malaria in India?

Accepted Answer

Anopheles culicifacies

Answer

Anopheles stephensi

Answer

Anopheles subpictus

Answer

Anopheles fluviatilis

Question 6

All are features of yellow fever except?

Accepted Answer

Validity of vaccination begins immediately after vaccination

Answer

Caused by vector aedes

Answer

IP 3-6 days

Answer

1 attack gives life long immunity

Question 7

In typhoid, a person is considered a permanent carrier if they excrete bacilli for more than how many months?

Accepted Answer

1 year

Answer

3 months

Answer

6 months

Answer

3 years

Question 8

What is the annual infection rate of tuberculosis?

Accepted Answer

Percentage of new patients positive for tuberculin test

Answer

Percentage of total patients positive for tuberculin test

Answer

Percentage of sputum positive total patients

Answer

Percentage of sputum positive new patients

Question 9

Which of the following statements best describes the operational definition of onchocerciasis elimination?

Accepted Answer

Transmission of O. volvulus has been reduced to a level where it cannot sustain itself in the population.

Answer

All interventions have been successfully implemented.

Answer

There is no recrudescence of the disease after a defined period.

Answer

All of the options are true.

Question 10

Which of the following IS included in the NVBDCP?

Accepted Answer

Chikungunya

Answer

Leprosy

Answer

Malaria

Answer

Dengue

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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