Infectious Diseases Practice Questions

Q: Considering that dogs are the most common carriers of rabies and that the disease predominantly affects children in developing countries, what is the most effective and direct method to significantly reduce the incidence of rabies?

Control the stray dog population and vaccinate all dogs. ***Control the stray dog population and vaccinate all dogs*** - As dogs are the primary reservoirs of rabies, controlling their population, coupled with widespread **dog vaccination**, is the most direct and effective strategy to break the transmission cycle to humans. - This approach tackles the root cause of the disease in areas where dog-mediated transmission is endemic, leading to a significant reduction in human rabies cases. *Conduct rabies testing for all dogs* - While testing identifies infected animals, it is **resource-intensive** and impractical for large dog populations, especially in low-resource settings, and does not prevent future infections. - This strategy is reactive rather than **proactive** in preventing the spread of rabies. *Enhance laboratory testing capabilities* - Improving laboratory testing capabilities is crucial for **surveillance** and accurate diagnosis but does not directly prevent rabies transmission at the source. - It's a supportive measure that helps monitor disease burden but isn't the most effective **primary intervention** for incidence reduction. *Improve healthcare worker training for disease surveillance* - Training healthcare workers enhances case detection and reporting, which is vital for **epidemiological monitoring** and timely post-exposure prophylaxis (PEP). - However, it does not address the fundamental issue of rabies transmission from dogs to humans and is not a direct prevention method for reducing disease incidence.

Q: Vector for Zika virus is:

Aedes. ***Aedes*** - The **Aedes mosquito** species, particularly *Aedes aegypti* and *Aedes albopictus*, is the primary vector for the transmission of the **Zika virus**. - These mosquitoes are also known vectors for other arboviruses, such as **Dengue** and **Chikungunya**. - **Aedes** mosquitoes are day-biting mosquitoes that breed in clean, stagnant water. *Culex* - **Culex mosquitoes** are the primary vectors for diseases like **West Nile virus** and **Japanese encephalitis**. - While *Culex* mosquitoes can occasionally carry the Zika virus in laboratory settings, they are not considered significant vectors for human transmission in nature. - These are primarily **night-biting** mosquitoes. *Anopheles* - **Anopheles mosquitoes** are the sole vectors responsible for transmitting **malaria parasites** to humans. - They do not play a significant role in the transmission of the Zika virus or other arboviral diseases. - These are also **night-biting** mosquitoes with a characteristic resting posture. *None of the options* - This option is incorrect because the **Aedes mosquito** is a well-established and recognized vector for the Zika virus. - The mode of transmission for Zika virus is primarily through mosquito bites, with identified vectors belonging to the *Aedes* genus.

Q: Which strain was responsible for the most recent Influenza pandemic?

H1N1. **Correct Option: H1N1** - The **H1N1 strain** of influenza virus was responsible for the **2009 swine flu pandemic**, which is considered the most recent global influenza pandemic. - This strain contained a unique combination of **influenza genes** not previously identified in animals or people, leading to widespread infection and human-to-human transmission. *Incorrect Option: H5N1* - **H5N1** is known for causing **avian influenza** (bird flu) and has occasionally infected humans, leading to severe disease and high mortality. - While it has epidemic potential, it has not caused a global pandemic with sustained human-to-human transmission. *Incorrect Option: H7N7* - **H7N7** is another avian influenza strain that has caused localized outbreaks in humans, primarily in those with close contact with infected birds. - It has not led to a widespread human pandemic. *Incorrect Option: H3N2* - **H3N2** is a common seasonal influenza strain that causes annual epidemics and has been responsible for past pandemics (e.g., the **1968 Hong Kong Flu**). - However, it was not the strain responsible for the most recent influenza pandemic in 2009.

Q: A patient with the following feature shown in the image. The patient reports having another 3-year-old sibling at home, who is fully immunized as per the immunization schedule. What is the best measure to prevent diphtheria in the sibling of the child with diphtheria?

Give prophylactic erythromycin. ***Correct: Give prophylactic erythromycin*** - Erythromycin is the **recommended antimicrobial prophylaxis** for close contacts of diphtheria patients to eradicate *Corynebacterium diphtheriae* carriage. - This prevents asymptomatic carriers from transmitting the bacteria, even if vaccinated, as vaccination provides immunity against the toxin, not necessarily against carriage. *Incorrect: Give diphtheria toxoid booster* - While immunization reduces the risk of symptomatic diphtheria disease by inducing **antitoxin immunity**, it does not reliably prevent nasal or pharyngeal carriage of the bacteria. - A booster might be considered if the last dose was more than 5 years ago, but it is not the primary immediate measure to prevent transmission from a known contact. *Incorrect: Give a full course of DPT vaccine* - The patient's sibling is already reported to be **fully immunized**, implying they have received the appropriate doses of the DPT vaccine according to the immunization schedule. - Giving a full course when already immunized would be redundant and ineffective to prevent immediate exposure and potential carriage. *Incorrect: Nothing is required to be done* - Close contacts of diphtheria cases are at **high risk of acquiring and transmitting the infection**, even if they are fully immunized, as immunization protects against the toxin but not necessarily carriage. - Failure to intervene would allow potential colonization and transmission, posing a risk to the community and the contact themselves.

Q: Which of the following statements regarding Japanese encephalitis is false?

Cattle are amplifier hosts. ***Cattle are amplifier hosts*** - Cattle are generally **not considered amplifier hosts** for Japanese encephalitis virus (JEV); instead, **pigs and wading birds** serve as primary amplifier hosts. - Amplifier hosts are crucial for **maintaining and spreading the virus** in the environment, leading to increased transmission to mosquito vectors. *Caused by flavivirus* - This statement is true; Japanese encephalitis virus (JEV) is indeed a **mosquito-borne flavivirus**, belonging to the *Flaviviridae* family. - Other notable flaviviruses include **Dengue, Zika, and West Nile viruses**. *Humans are dead-end hosts* - This statement is true; humans are considered **dead-end hosts** for JEV because the viremia levels achieved in infected humans are generally too low to infect mosquitoes. - Therefore, humans **do not contribute significantly to the transmission cycle** of the virus among mosquito vectors and other hosts. *Transmitted by culex* - This statement is true; Japanese encephalitis is primarily transmitted by **mosquitoes of the *Culex* genus**, especially *Culex tritaeniorhynchus*. - These mosquitoes typically **breed in rice paddies** and other agricultural areas.

Q: Which of the following is an example of indirect transmission in communicable diseases?

Soil-borne transmission. ***Soil-borne transmission*** - This involves an **intermediate vehicle** (soil) contaminated with infectious agents, facilitating transmission without direct host-to-host contact. - Diseases like **tetanus** (Clostridium tetani spores) and **hookworm infections** are classic examples where contaminated soil acts as a reservoir. *Transplacental transmission* - This is a form of **vertical transmission**, where the infectious agent passes directly from mother to fetus via the placenta. - It is considered a form of **direct transmission** as there is no external intermediary. *Sexually transmitted diseases (STDs)* - These are typically transmitted through **direct person-to-person contact** during sexual activity. - This is a clear example of **direct transmission**, involving close physical contact between individuals. *Respiratory droplet transmission* - This occurs when droplets expelled from an infected person's respiratory tract land on the mucous membranes of a susceptible person. - While it involves airborne particles, it's generally considered a form of **direct transmission** when the droplets travel a short distance, or in some contexts, can bridge to an indirect form if they settle on surfaces before contact.

Q: Kala-Azar is found in all endemic areas except for which of the following?

Himachal Pradesh. ***Himachal Pradesh*** - **Kala-azar (visceral leishmaniasis)** is endemic to specific regions in India, primarily the Gangetic plains. - Himachal Pradesh is a **non-endemic state** for kala-azar, differentiating it from the other options. *West Bengal* - West Bengal is one of the **highly endemic states** for kala-azar in India due to favorable environmental and socioeconomic conditions for the sandfly vector. - It has a significant burden of the disease, particularly in its northern and central districts. *Uttar Pradesh* - Uttar Pradesh is another **endemic state** for kala-azar, particularly the eastern parts bordering Bihar. - The disease is prevalent in districts along the Ganges river basin, contributing to the overall disease burden in India. *Bihar* - Bihar is considered the **most highly endemic state** for kala-azar in India, accounting for a large proportion of cases. - High poverty, poor housing, and a suitable environment for the sandfly vector contribute to its significant prevalence in the state.

Q: Contact isolation is done for

MRSA. ***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).

Q: Reduced osmolarity ORS does not contain which of the following ions?

Lactate. ***Lactate*** - The **reduced osmolarity ORS** formulation replaced **bicarbonate** with **citrate** and does not contain lactate. - **Citrate** is preferred over lactate / bicarbonate due to its stability, longer shelf life, and ease of dissolution. *Sodium* - **Sodium** is a crucial component of ORS, as it is co-transported with glucose into enterocytes, facilitating water absorption through **solvent drag**. - Reduced osmolarity ORS has a **lower sodium concentration** (75 mEq/L) compared to standard ORS (90 mEq/L) to minimize hypernatremia risk and enhance water absorption. *Potassium* - **Potassium** is included in ORS to replace intestinal losses, as **diarrhea** leads to significant potassium depletion. - Maintaining adequate **potassium levels** is essential for normal cellular function and preventing hypokalemia-related complications. *Citrate* - **Citrate** is a component of ORS that serves as an **alkalinizing agent** to correct metabolic acidosis often associated with dehydration in diarrheal diseases. - It also enhances the absorption of sodium and water in the intestine.

Question 1

Considering that dogs are the most common carriers of rabies and that the disease predominantly affects children in developing countries, what is the most effective and direct method to significantly reduce the incidence of rabies?

Accepted Answer

Control the stray dog population and vaccinate all dogs

Answer

Conduct rabies testing for all dogs

Answer

Enhance laboratory testing capabilities

Answer

Improve healthcare worker training for disease surveillance

Question 2

Vector for Zika virus is:

Accepted Answer

Aedes

Answer

Culex

Answer

Anopheles

Answer

None of the options

Question 3

Which strain was responsible for the most recent Influenza pandemic?

Accepted Answer

H1N1

Answer

H5N1

Answer

H7N7

Answer

H3N2

Question 4

A patient with the following feature shown in the image. The patient reports having another 3-year-old sibling at home, who is fully immunized as per the immunization schedule. What is the best measure to prevent diphtheria in the sibling of the child with diphtheria?

Accepted Answer

Give prophylactic erythromycin

Answer

Give diphtheria toxoid booster

Answer

Give a full course of DPT vaccine

Answer

Nothing is required to be done

Question 5

Which of the following statements regarding Japanese encephalitis is false?

Accepted Answer

Cattle are amplifier hosts

Answer

Humans are dead-end hosts

Answer

Transmitted by culex

Answer

Caused by flavivirus

Question 6

Which of the following is an example of indirect transmission in communicable diseases?

Accepted Answer

Soil-borne transmission

Answer

Sexually transmitted diseases (STDs)

Answer

Transplacental transmission

Answer

Respiratory droplet transmission

Question 7

Kala-Azar is found in all endemic areas except for which of the following?

Accepted Answer

Himachal Pradesh

Answer

Uttar Pradesh

Answer

West Bengal

Answer

Bihar

Question 8

Contact isolation is done for

Accepted Answer

MRSA

Answer

Mumps

Answer

Asthma

Answer

Diphtheria

Question 9

Reduced osmolarity ORS does not contain which of the following ions?

Accepted Answer

Lactate

Answer

Sodium

Answer

Potassium

Answer

Citrate

Question 10

What is the definition of a reservoir in the context of infectious diseases?

Accepted Answer

Person, animal or substance in which infectious agent lives and multiplies

Answer

Person, animal or object from which infectious agent is transmitted to host

Answer

Person or animal in which infectious agent causes a disease

Answer

Person or animal that transmits the infectious agent mechanically

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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