Infectious Diseases Practice Questions

Q: Which of the following is a distinguishing feature of Aedes mosquitoes compared to Anopheles mosquitoes?

Wings unspotted. ***Wings unspotted*** - **Aedes mosquitoes have unspotted wings**, which is a key distinguishing feature for adult identification. - *Anopheles* mosquitoes characteristically have **spotted wings** with patches of dark and pale scales, making this a reliable diagnostic criterion. - This is one of the most practical features for field identification of adult mosquitoes. *Pupa has a narrow siphon* - This is **incorrect** - *Aedes* pupae actually have a **broad and short respiratory siphon (trumpet)**. - *Anopheles* pupae have a **narrow and long siphon**, which is the opposite of what this option states. - Pupal characteristics are useful but require microscopic examination. *Pupa has broad siphon* - While *Aedes* pupae do have a **broader siphon** compared to *Anopheles*, this is less commonly used for routine identification. - The broad siphon refers to the respiratory trumpet structure at the cephalothorax. - However, **wing spotting pattern** remains the preferred adult identification method. *Eggs are oval shaped* - *Aedes* eggs are **oval/elongated and laid singly**, often on moist surfaces above the waterline. - *Anopheles* eggs are also **boat-shaped with lateral floats** and laid singly on the water surface. - Both genera have oval-shaped eggs, making this a less reliable distinguishing feature alone.

Q: In which months does the maximum spread of malaria typically occur in many endemic regions of India?

September - October. ***September-October*** - The **peak transmission** season for **malaria** in many endemic regions of India occurs during the **post-monsoon** months. - This period provides optimal conditions for **mosquito breeding** due to accumulated water collections, moderate temperatures, and suitable humidity levels after the monsoon rains. - **Post-monsoon months** allow for maturation of mosquito populations that bred during monsoon, leading to maximum vector density and malaria transmission. *April-May* - These **pre-monsoon** months may show increased transmission in some regions, but this is **not the universal peak period** across India. - The preceding dry season usually means **fewer breeding sites** compared to post-monsoon period. - Temperatures are rising but **water collections are limited** before monsoon onset. *January-February* - These months typically represent the **winter season** in most parts of India where malaria is endemic. - **Lower temperatures** and reduced humidity are generally unfavorable for the survival of the *Anopheles* mosquito and the development of the *Plasmodium* parasite within the mosquito. - This represents the **lowest transmission period** in most endemic areas. *March-April* - While malaria transmission may begin to increase in these months, it generally **peaks later** after monsoon rains create abundant breeding sites. - The dry season conditions still prevail, limiting **vector breeding opportunities** compared to post-monsoon months.

Q: Which one of the following insecticides is most commonly used for ultra-low-volume fogging?

Malathion. ***Malathion*** - **Malathion** is a widely used organophosphate insecticide favored in **ultra-low-volume (ULV) fogging** due to its effectiveness against adult mosquitoes and its relatively rapid degradation in the environment. - Its properties allow for dispersion as fine aerosols, effectively covering large areas with minimal environmental residue. *Abate* - **Abate** (temephos) is primarily an **organophosphate larvicide**, used in standing water to control mosquito larvae. - It is not commonly used for ULV fogging, which targets adult mosquitoes. *DDT* - **DDT** (dichlorodiphenyltrichloroethane) is a persistent organochlorine insecticide that was once widely used but is now **restricted or banned** in most countries due to its environmental persistence and toxic effects. - It is not a common choice for ULV fogging in modern pest control. *Paris green* - **Paris green** (copper(II) acetoarsenite) is an inorganic compound historically used as an insecticide, particularly against **Anopheles larvae** in malarial control. - Due to its **high toxicity** (containing arsenic), it is rarely used today, and not suitable for ULV fogging.

Q: At what altitude is kala azar unlikely to occur?

600 meters. ***600 meters*** - Kala-azar, or **visceral leishmaniasis**, is primarily found in **low-lying areas** and is rarely reported at altitudes above 600 meters due to the specific ecological requirements of its **sand fly vector**. - The **Phlebotomus argentipes sand fly**, the main vector in the Indian subcontinent, prefers warm, humid climates and **lower altitudes**. *400 meters* - This altitude is within the **typical endemic range** for kala-azar, especially in regions like the Indian subcontinent. - The environmental conditions at 400 meters are generally conducive for the **survival and breeding** of the sand fly vector. *500 meters* - Similar to 400 meters, 500 meters is still considered within the **favorable altitude range** for kala-azar transmission. - The **sand fly vector** can thrive in the climate often found at this elevation. *200 meters* - This altitude represents a **highly endemic zone** for kala-azar, as it provides optimal conditions for the sand fly vector. - Lower altitudes are typically associated with increased **humidity and warmth**, favoring vector density and parasite transmission.

Q: Chemoprophylaxis is done for all except which of the following?

Cholera. ***Cholera*** - **Chemoprophylaxis is generally not recommended for cholera** due to the rapid onset and short incubation period, making widespread prophylactic antibiotic use impractical and potentially contributing to **antibiotic resistance**. - WHO guidelines emphasize **prompt rehydration therapy**, improving sanitation/hygiene, and oral cholera vaccine rather than mass chemoprophylaxis. *Taeniasis* - **Chemoprophylaxis is not a standard practice** for taeniasis prevention. Control measures focus on **proper cooking of pork**, meat inspection, and improved sanitation. - While **praziquantel** is effective for **treatment** of established infection, routine prophylactic use is not recommended in public health practice. *Malaria* - **Malaria chemoprophylaxis is a cornerstone of prevention** for travelers to endemic areas and can be used in certain high-risk populations within endemic regions (e.g., pregnant women, children). - Drugs like **mefloquine, doxycycline, and atovaquone-proguanil** are commonly prescribed to prevent infection. *Leprosy* - **Post-exposure chemoprophylaxis** with a single dose of **rifampicin** is a recommended WHO strategy for close contacts of individuals with newly diagnosed multibacillary leprosy to reduce the risk of developing the disease. - The aim is to **prevent new cases** and interrupt transmission within high-risk groups.

Q: What term describes an infection or infectious disease that is transmissible under natural conditions from vertebrate animals to humans?

Zoonoses. ***Zoonoses*** - A **zoonosis** is an infectious disease that can be **transmitted naturally from vertebrate animals to humans**. - Examples include rabies, Lyme disease, and influenza, where animals act as natural hosts or reservoirs for the pathogen. *Epizootic* - **Epizootic** refers to a disease event in an **animal population** that is analogous to an **epidemic in humans**, indicating a sudden and widespread outbreak. - It describes the prevalence pattern of a disease within an animal population, not the transmission across species to humans. *Epornithic* - **Epornithic** is a term specifically used for an outbreak of disease within a **bird population**, similar to how epizootic refers to animals in general. - This term does not describe the transmission of disease from animals to humans, but rather the incidence within birds. *Exotic* - **Exotic** refers to something originating in or characteristic of a distant foreign country, often implying something unusual or introduced from outside. - It does not specifically describe a type of infectious disease or its transmissibility from animals to humans.

Q: Which of the following diseases does not require strict isolation?

Hepatitis A. ***Hepatitis A*** - While **contact precautions** are important for Hepatitis A to prevent fecal-oral transmission, **strict isolation** like airborne or droplet precautions typically isn't required in the same way as highly transmissible respiratory diseases. - Its primary mode of transmission is **fecal-oral**, making good hygiene and contact precautions effective in preventing its spread. *Mumps* - Mumps requires **droplet precautions** because it is transmitted through respiratory droplets from coughing, sneezing, or talking. - This necessitates isolation to prevent its spread in healthcare settings. *Measles* - Measles is highly contagious and spreads via **airborne transmission**, meaning the virus can remain suspended in the air for extended periods. - It requires **airborne isolation** (e.g., in a negative pressure room) to prevent widespread transmission. *Pneumonic plague* - Pneumonic plague is a severe respiratory illness that is transmitted through **respiratory droplets** and requires strict **droplet precautions** and often airborne precautions due to its high infectivity and mortality rate. - This necessitates isolation to contain the spread of the highly virulent *Yersinia pestis* bacterium.

Q: Which of the following is the most common risk factor for Staphylococcal food poisoning?

Commonly associated with improper food handling.. ***Commonly associated with improper food handling.*** - **Improper food handling** is the **most common risk factor** for Staphylococcal food poisoning - This includes inadequate refrigeration, poor personal hygiene (S. aureus colonizes skin and nasal passages), and allowing food to remain at room temperature - These conditions allow *Staphylococcus aureus* to multiply and produce enterotoxins in food - Common culprits include custards, salads (egg, tuna, potato), cream-filled pastries, and processed meats left unrefrigerated *Caused by enterotoxins produced by Staphylococcus aureus.* - While this is the **mechanism** of illness, it is not the risk factor - The enterotoxins (SEs) are preformed in food and cause rapid onset symptoms (1-6 hours) - This describes *what causes* the illness, not the risk factor that leads to toxin production *Caused by heat-stable enterotoxins found in contaminated foods.* - This also describes the **mechanism**, not the risk factor - The heat-stable nature means cooking contaminated food will not destroy the toxins - Prevention requires proper handling *before* toxin production occurs *Not associated with fish.* - This is an irrelevant statement about food association - S. aureus food poisoning can occur with various foods when improperly handled - Fish is more commonly associated with other pathogens (Vibrio, Ciguatera)

Question 1

Which of the following is a distinguishing feature of Aedes mosquitoes compared to Anopheles mosquitoes?

Accepted Answer

Wings unspotted

Answer

Pupa has broad siphon

Answer

Pupa has a narrow siphon

Answer

Eggs are oval shaped

Question 2

In which months does the maximum spread of malaria typically occur in many endemic regions of India?

Accepted Answer

September - October

Answer

March-April

Answer

January-February

Answer

April-May

Question 3

Which one of the following insecticides is most commonly used for ultra-low-volume fogging?

Accepted Answer

Malathion

Answer

Abate

Answer

DDT

Answer

Paris green

Question 4

At what altitude is kala azar unlikely to occur?

Accepted Answer

600 meters

Answer

400 meters

Answer

500 meters

Answer

200 meters

Question 5

Chemoprophylaxis is done for all except which of the following?

Accepted Answer

Cholera

Answer

Malaria

Answer

Leprosy

Answer

Taeniasis

Question 6

A 25-year-old female has been diagnosed with tuberculosis and has a history of previous TB treatment (relapse case). What is the treatment regimen recommended under the current National Tuberculosis Elimination Programme (NTEP) for this previously treated patient?

Accepted Answer

2 months of H, R, Z, E daily or thrice weekly + 4 months of H, R, E daily or thrice weekly

Answer

2 months of H, R, S, Z, E thrice weekly + 1 month of H, R, Z, E thrice weekly + 5 months of H, R thrice weekly

Answer

3 months of H, R, Z, E thrice weekly + 3 months of H, R thrice weekly

Answer

3 months of H, R, S, Z, E thrice weekly + 1 month of H, R thrice weekly + 6 months of continuation phase (incomplete regimen)

Question 7

What term describes an infection or infectious disease that is transmissible under natural conditions from vertebrate animals to humans?

Accepted Answer

Zoonoses

Answer

Epizootic

Answer

Epornithic

Answer

Exotic

Question 8

Which of the following diseases does not require strict isolation?

Accepted Answer

Hepatitis A

Answer

Pneumonic plague

Answer

Mumps

Answer

Measles

Question 9

Which of the following is the most common risk factor for Staphylococcal food poisoning?

Accepted Answer

Commonly associated with improper food handling.

Answer

Not associated with fish.

Answer

Caused by enterotoxins produced by Staphylococcus aureus.

Answer

Caused by heat-stable enterotoxins found in contaminated foods.

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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