Infectious Diseases Practice Questions

Q: Which of the following statements about Culex larvae is correct?

Siphon tube present. ***Siphon tube present*** - **Culex larvae** possess a prominent **siphon tube** at their posterior end, which is used for breathing by extending to the water surface. - This **siphon tube** is a key morphological feature that helps distinguish them from *Anopheles* larvae. *Rest parallel to surface water* - **Anopheles larvae** typically rest parallel to the water surface because they lack a long siphon and obtain oxygen directly through spiracles on their dorsal surface. - **Culex larvae**, due to their siphon tube, hang head-down at an angle from the water surface. *Long Palmate hair* - **Palmate hairs** are characteristic structures found on the abdomen of **Anopheles larvae** that help them float horizontally at the water surface. - **Culex larvae** do not possess well-developed palmate hairs. *All are false* - This statement is incorrect because the presence of a **siphon tube** is a defining characteristic of **Culex larvae**.

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: Which of the following statements about influenza infectivity is correct?

All of the options are correct.. ***All of the options are correct.*** - All statements provided accurately describe aspects of influenza infectivity and epidemiology. - The **communicable period**, the **primary source of infection**, and the potential for **subclinical cases** are all characteristic features of influenza. *Communicable period is 1 day before to 5-7 days after the onset of symptoms* - This statement is accurate, as influenza is transmissible **before symptom onset** and for several days afterward, which contributes to its rapid spread. - Peak viral shedding often occurs just before and in the first few days of symptomatic illness. - Adults typically shed virus from 1 day before to 5-7 days after symptom onset (can be longer in children and immunocompromised individuals). *The primary source of infection is a clinical case.* - This is correct, as **symptomatic individuals (clinical cases) are the PRIMARY source** of influenza virus transmission to others. - Respiratory droplets produced by coughing, sneezing, or talking from an infected person are the main mode of spread. - While subclinical cases can transmit, clinical cases with overt symptoms produce more respiratory droplets and are the major drivers of transmission. *There can be subclinical cases of influenza.* - This statement is correct; many individuals infected with influenza virus experience **mild or asymptomatic infections** (subclinical cases). - These subclinical cases can still transmit the virus, though typically to a lesser extent than symptomatic cases, further complicating control efforts.

Q: Which of the following larvicide is used under urban Malaria Scheme?

Abate. ***Abate*** - **Abate (temephos)** is an organophosphate larvicide widely used in public health programs, including the urban malaria scheme, due to its effectiveness against mosquito larvae at low concentrations. - It is applied to water storage containers, wells, and other mosquito breeding sites to **prevent the development of adult mosquitoes**. *Malathion* - **Malathion** is an organophosphate insecticide primarily used as an **adulticide** for fogging operations against adult mosquitoes, not specifically as a larvicide in urban schemes. - While it can kill larvae, its primary application and efficacy are geared towards **adult mosquito control**. *Parathion* - **Parathion** is a highly toxic organophosphate insecticide that is generally **not used in public health programs** due to its significant environmental and human health risks. - Its use is largely restricted to agricultural pest control and is **not a recommended larvicide** for urban settings. *DDT* - **DDT (dichlorodiphenyltrichloroethane)** is a persistent organic pollutant whose use has been largely banned or severely restricted globally due to its **environmental impact** and long-term toxicity. - While historically used for mosquito control (both larvae and adults), it is **not used in current urban malaria schemes** due to its banned status in many regions and resistance issues.

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

Passive. ***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.

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

DEC. ***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.

Q: Human, animal, fomite or objects from which infective organism enters the host is called?

Source of infection. ***Source of infection*** - The **source of infection** refers to the person, animal, object, or substance from which an infectious agent passes immediately to a host. - This can include humans, animals, fomites, or contaminated objects that directly transmit the infectious organism. - This is the proximate source from which the agent enters the host. *Infective Reservoir* - An **infective reservoir** is the long-term habitat where an infectious agent normally lives, grows, and multiplies. - The reservoir can be human, animal, plant, soil, or inanimate matter where the agent is normally found. - While a reservoir can be a source, the source is specifically the immediate point from which transmission occurs. *Infective Carrier* - An **infective carrier** is an infected person or animal that harbors a specific infectious agent without showing clinical symptoms but can transmit it to others. - A carrier is a type of source (when transmission occurs from them), but the term "source" is broader, encompassing inanimate objects and fomites as well. *None of the above* - This option is incorrect because **Source of infection** accurately describes the concept presented in the question.

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: If a claw hand develops in a patient with Leprosy, what is the classification of the deformity?

Grade II. A **claw hand** deformity, characterized by hyperextension of the metacarpophalangeal joints and flexion of the interphalangeal joints, indicates a significant and **visible disability** but the affected part is still functional to a limited degree. In the context of leprosy, this observable and permanent deformity falls under **Grade II** on the WHO disability grading scale, signifying a clear and established disability. This grade indicates **no disability** or deformity related to leprosy. A patient with a claw hand has an obvious physical deformity and functional impairment, thus not fitting this classification. This grade refers to a **detectable impairment** but **no visible deformity**. A claw hand is a clearly visible deformity, making Grade I an inappropriate classification. While Grades are typically 0, I, and II in the WHO disability grading for leprosy, some classifications might refer to severe, non-functional deformities as higher grades. However, Grade II adequately captures **visible and significant deformities** like a claw hand, and a Grade III is not a standard or commonly used classification for a claw hand in leprosy in the WHO system.

Question 1

Which of the following statements about Culex larvae is correct?

Accepted Answer

Siphon tube present

Answer

Rest parallel to surface water

Answer

Long Palmate hair

Answer

All are false

Question 2

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 3

Which of the following statements about influenza infectivity is correct?

Accepted Answer

All of the options are correct.

Answer

Communicable period is 1 day before to 5-7 days after the onset of symptoms

Answer

There can be subclinical cases of influenza.

Answer

The primary source of infection is a clinical case.

Question 4

Which of the following statements about universal precautions is false?

Accepted Answer

Consider that all body fluids are contaminated with blood

Answer

Includes use of hand washing

Answer

Includes use of gloves and masks

Answer

To prevent transmission of blood borne pathogens

Question 5

Which of the following larvicide is used under urban Malaria Scheme?

Accepted Answer

Abate

Answer

Malathion

Answer

Parathion

Answer

DDT

Question 6

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

Accepted Answer

Passive

Answer

Active

Answer

Mass

Answer

None of the options

Question 7

Drug of choice for mass therapy under filariasis control programme?

Accepted Answer

DEC

Answer

Albendazole

Answer

Ivermectin

Answer

Mebendazole

Question 8

Human, animal, fomite or objects from which infective organism enters the host is called?

Accepted Answer

Source of infection

Answer

Infective Reservoir

Answer

Infective Carrier

Answer

None of the above

Question 9

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 10

If a claw hand develops in a patient with Leprosy, what is the classification of the deformity?

Accepted Answer

Grade II

Answer

Grade 0

Answer

Grade I

Answer

Grade III

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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