Infectious Diseases Practice Questions

Q: Among various species of mosquitoes belonging to Anopheles genus, one that is highly anthropophilic and transmits even at low density is

Anopheles fluviatilis. ***Anopheles fluviatilis*** - This species is known for being **highly anthropophilic** (prefers human blood) and having a high vectorial capacity, allowing it to transmit malaria effectively even at **low mosquito densities**. - Its efficient transmission at low densities makes it a significant vector, particularly in forest and foothill regions. *Anopheles culicifacies* - This is a major vector in rural India, particularly prevalent in **agricultural areas** and at higher densities. - While an important vector, it is generally associated with higher densities for efficient transmission compared to *An. fluviatilis*. *Anopheles stephensi* - This species is a primary vector in **urban and peri-urban areas**, adapted to breeding in domestic water containers. - While anthropophilic, its transmission efficiency at very low densities is not as pronounced as *An. fluviatilis* in its characteristic habitats. *Anopheles sundaicus* - This species is typically found in **coastal saline or brackish water** breeding sites in Southeast Asia. - While it is an important vector in those specific ecological niches, it doesn't possess the same level of efficient low-density transmission and broad anthropophilic behavior as *An. fluviatilis* across different settings.

Q: Which of the following actions can help in the prevention of HIV transmission?

Using safe injection techniques. ***Using safe injection techniques*** - HIV can be transmitted through the sharing of needles and syringes, particularly among **intravenous drug users**, due to the direct transfer of infected blood. - Practicing **safe injection techniques**, such as using sterile needles and syringes for each injection, significantly reduces the risk of HIV transmission in these populations. *Avoidance of smoking by drivers* - This action is primarily related to **respiratory health** and **traffic safety**, as smoking can lead to lung diseases and impair concentration. - It has **no direct relevance** to the prevention of human immunodeficiency virus (HIV) transmission. *Use of copper T by sex workers* - A **copper T (intrauterine device)** is a form of contraception that prevents pregnancy by creating a local inflammatory reaction in the uterus. - It does **not offer protection** against sexually transmitted infections (STIs), including HIV, which requires barrier methods like condoms for prevention. *Prohibiting voluntary blood donation* - **Voluntary blood donation** is a crucial source of blood products for medical treatments and emergencies. Screening practices ensure the safety of donated blood. - Prohibiting it would **deplete blood supplies** and does not prevent HIV transmission, as modern blood screening protocols effectively identify and discard HIV-infected blood units.

Q: The incubation period for polio is

7 - 14 days. **7 - 14 days** - The **incubation period** for poliovirus, from exposure to the onset of initial symptoms, typically ranges from **7 to 14 days**. - This period allows the virus to replicate in the **gastrointestinal tract** and lymphatic tissue before potentially invading the central nervous system. *1 - 2 years* - An incubation period of **1-2 years** is far too long for poliovirus and is characteristic of diseases like **Kuru** or certain **slow viral infections**. - Poliovirus progresses much more rapidly, typically within weeks. *2 - 3 weeks* - While some viral infections can have an incubation period of **2-3 weeks**, this is slightly longer than the typical range for poliovirus. - The average presentation for polio symptoms is usually within the second week post-exposure. *3 - 7 days* - An incubation period of **3-7 days** is possible for some very rapidly acting viruses, but it is generally a bit shorter than the common range for poliovirus. - Most poliovirus cases manifest symptoms closer to the one-to-two-week mark.

Q: Which of the following is NOT transmitted by soft ticks?

KFD in India. ***KFD in India*** - **Kyasanur Forest Disease (KFD)** in India is transmitted by **hard tick** species *Haemaphysalis spinigera*, NOT by soft ticks. - This is a viral hemorrhagic fever endemic to Karnataka and neighboring states in India. - Since it is NOT transmitted by soft ticks, this is the correct answer. *Q fever* - **Q fever** (*Coxiella burnetii*) can be transmitted by both **hard ticks** and **soft ticks**. - Primary transmission occurs through inhalation of contaminated aerosols from infected animals. - Since it CAN be transmitted by soft ticks, this is incorrect. *KFD outside India* - **Alkhurma hemorrhagic fever virus (AHFV)**, a close relative of KFD virus, occurs in the Middle East and is transmitted by **hard ticks** (*Ornithodoros savignyi* and *Hyalomma* species). - Related flaviviruses outside India follow similar hard tick transmission patterns. - This option may cause confusion but generally refers to KFD-like diseases transmitted by hard ticks, not soft ticks. *Relapsing fever* - **Tick-borne relapsing fever** (caused by *Borrelia* species) is classically transmitted by **soft ticks** of the genus *Ornithodoros*. - Since it IS transmitted by soft ticks, this is incorrect. - This differentiates it from Lyme disease, which is transmitted by hard ticks (*Ixodes* species).

Q: Crimean-Congo Hemorrhagic Fever is transmitted by?

Ticks. ***Ticks*** - Crimean-Congo Hemorrhagic Fever (CCHF) is primarily transmitted to humans through the bite of infected **Hyalomma ticks**. - Transmission can also occur through contact with infected animal blood or tissues, or through contact with infected human body fluids. *Cat fish* - **Catfish** are aquatic animals and are not known vectors for the transmission of viral diseases like CCHF. - Their habitat and interaction with humans do not facilitate the spread of tick-borne illnesses. *Mosquitoes* - **Mosquitoes** are vectors for diseases like dengue, malaria, and Zika, but not for CCHF. - CCHF is caused by a Nairovirus, which typically requires a tick vector for its lifecycle and transmission to humans. *Mites* - While some **mites** can transmit diseases (e.g., scrub typhus), they are not the primary or significant vector for Crimean-Congo Hemorrhagic Fever. - The main vector for CCHF is specified as ticks, particularly the Hyalomma genus.

Q: Which of the following acts as a vector of West Nile fever?

Culex mosquito. ***Culex mosquito*** - The **Culex mosquito** genus is the primary vector for West Nile virus transmission to humans. - These mosquitoes commonly acquire the virus by feeding on **infected birds** and then transmit it to other animals and humans. *Tick* - **Ticks** are known vectors for diseases like **Lyme disease** (Borrelia burgdorferi) and **Rocky Mountain spotted fever** (Rickettsia rickettsii). - They are not vectors for West Nile fever. *Mite* - **Mites** can transmit diseases such as **scrub typhus** (Orientia tsutsugamushi) and **rickettsial pox** (Rickettsia akari). - They are not associated with the transmission of West Nile virus. *Flea* - **Fleas** are well-known vectors for diseases like **bubonic plague** (Yersinia pestis) and **murine typhus** (Rickettsia typhi). - They do not transmit West Nile fever.

Q: In an epidemic of plague, within 48 hours of application of insecticides by spraying, the X. cheopis index should fall to:

0. ***Correct Answer: 0*** - In an epidemic of plague, the immediate goal of insecticide spraying is to rapidly eliminate the **flea vectors**, primarily *Xenopsylla cheopis*. - A successful intervention aims for a rapid reduction to **zero live fleas** within 48 hours to halt transmission as quickly as possible. *Incorrect: 5* - An X. cheopis index of 5 would still indicate a significant presence of fleas, suggesting **ineffective vector control** and continued risk of plague transmission. - This level is far above the desired target for emergency plague control. *Incorrect: 2* - While lower than 5, an X. cheopis index of 2 still signifies the presence of live fleas capable of transmitting the disease, indicating an **incomplete elimination effort**. - The objective in a plague epidemic is complete disruption of the transmission chain, which requires a zero index. *Incorrect: 1* - An X. cheopis index of 1, though very low, still means there is at least one active flea per rodent on average, which poses an **ongoing risk of disease transmission**. - The critical nature of plague control necessitates achieving an index of zero to ensure complete cessation of vector-borne spread within 48 hours.

Q: SARS is most commonly seen in which of the following groups?

Health care workers. ***Health care workers*** - **SARS (Severe Acute Respiratory Syndrome)** is a viral respiratory illness known to spread easily, particularly in close-contact environments where aerosol-generating procedures might be performed. - Due to their direct exposure to infected patients and potential involvement in diagnostic and therapeutic procedures, **healthcare workers** are at a significantly higher risk of contracting and transmitting SARS compared to the general population. *Coal miners* - **Coal miners** are primarily at risk for respiratory diseases like **coal worker's pneumoconiosis** (black lung disease) due to chronic exposure to coal dust, not viral infections like SARS. - This group's occupational hazards are related to particulate matter, not infectious agents commonly associated with SARS outbreaks. *School kids* - While respiratory viruses can spread in schools, **SARS outbreaks** were not primarily characterized by widespread infection in children, largely due to differences in exposure patterns and potentially milder disease presentation in younger populations. - The initial outbreaks and severe cases of SARS predominantly impacted adults, especially in healthcare settings. *Pregnancy* - **Pregnancy** itself does not make individuals inherently more susceptible to contracting SARS; rather, if a pregnant individual contracts SARS, they may experience more severe outcomes. - While important for maternal and fetal health, this group is not identified as the most common demographic for initial SARS acquisition.

Q: Most important strategy for control of malaria in an endemic area:

Vector control. ***Vector control*** - **Vector control** strategies, such as **insecticide-treated bed nets (ITNs)** and **indoor residual spraying (IRS)**, are the most effective in reducing malaria transmission by targeting the Anopheles mosquito - By reducing the mosquito population and their biting rates, vector control significantly cuts down the number of infected bites, leading to a substantial decrease in malaria incidence - This is the **cornerstone of WHO's Global Malaria Programme** and has proven most cost-effective for endemic areas *Incorrect: Chemoprophylaxis* - Chemoprophylaxis involves taking antimalarial drugs to prevent infection, which is effective for individuals or travelers but not sustainable or scalable for mass control in endemic populations - Widespread use would be cost-prohibitive and could accelerate **antimalarial drug resistance** *Incorrect: Early treatment of cases* - Early treatment with effective antimalarials reduces disease severity and prevents onward transmission, which is crucial for managing the disease burden - However, it does not directly prevent new infections or interrupt the transmission cycle as effectively as vector control at a population level - This is a **secondary strategy** that complements but does not replace vector control *Incorrect: Elimination of plasmodium* - Elimination of Plasmodium refers to eradication of the parasite, which is the ultimate goal, but it is not a direct "strategy" in itself but rather the **outcome** of successful control measures - Complete eradication is ambitious and challenging; current efforts focus on breaking the transmission cycle through vector control and effective case management

Question 1

True statement about plague is -

Accepted Answer

Most important measure to control epidemic is rodent control

Answer

Septicemic plague is highly infectious

Answer

Live attenuated vaccines are used

Answer

Vaccine is not used to control epidemic of pneumonic plague

Question 2

Among various species of mosquitoes belonging to Anopheles genus, one that is highly anthropophilic and transmits even at low density is

Accepted Answer

Anopheles fluviatilis

Answer

Anopheles culicifacies

Answer

Anopheles stephensi

Answer

Anopheles sundaicus

Question 3

Which of the following actions can help in the prevention of HIV transmission?

Accepted Answer

Using safe injection techniques

Answer

Avoidance of smoking by drivers

Answer

Use of copper T by sex workers

Answer

Prohibiting voluntary blood donation

Question 4

The incubation period for polio is

Accepted Answer

7 - 14 days

Answer

1 - 2 years

Answer

2 - 3 weeks

Answer

3 - 7 days

Question 5

Which of the following is NOT transmitted by soft ticks?

Accepted Answer

KFD in India

Answer

Q fever

Answer

KFD outside India

Answer

Relapsing fever

Question 6

Crimean-Congo Hemorrhagic Fever is transmitted by?

Accepted Answer

Ticks

Answer

Catfish

Answer

Mosquitoes

Answer

Mites

Question 7

Which of the following acts as a vector of West Nile fever?

Accepted Answer

Culex mosquito

Answer

Tick

Answer

Mite

Answer

Flea

Question 8

In an epidemic of plague, within 48 hours of application of insecticides by spraying, the X. cheopis index should fall to:

Accepted Answer

0

Answer

5

Answer

2

Answer

1

Question 9

SARS is most commonly seen in which of the following groups?

Accepted Answer

Health care workers

Answer

Coal miners

Answer

School kids

Answer

Pregnancy

Question 10

Most important strategy for control of malaria in an endemic area:

Accepted Answer

Vector control

Answer

Chemoprophylaxis

Answer

Early treatment of cases

Answer

Elimination of plasmodium

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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