Infectious Diseases Practice Questions

Q: Which Anopheles species is commonly found in urban areas?

Anopheles stephensi. ***Stephensi*** - **Anopheles stephensi** is well-known for its ability to adapt and thrive in **urban environments**, utilizing man-made breeding sites like cisterns, overhead tanks, and construction sites. - Its presence in urban areas makes it a significant vector for **malaria transmission** in cities across Asia and the Middle East, posing a public health challenge. *Culicifacies* - **Anopheles culicifacies** is primarily found in **rural and semi-urban areas**, where it breeds in natural water collections such as irrigation channels, rice fields, and ponds. - While it is a major vector in many regions, it is less commonly associated with densely populated urban centers compared to Anopheles stephensi. *None of the options* - This option is incorrect as **Anopheles stephensi** is recognized as a significant urban malaria vector. - Specific Anopheles species exhibit distinct ecological preferences, and some are highly adapted to urban settings. *Fluvitalis* - **Anopheles fluviatilis** is typically found in **hilly and forested areas**, breeding in clear, slow-moving streams and rivers. - Its ecological niche is generally restricted to natural rural environments, not urban conglomerations.

Q: Case finding in RNTCP is based on -

Sputum microscopy. ***Sputum microscopy*** - Within the **Revised National Tuberculosis Control Programme (RNTCP)**, sputum microscopy for **acid-fast bacilli (AFB)** was established as the primary method for initial **case finding and diagnosis** of pulmonary TB, particularly in peripheral health facilities. - It is a **cost-effective and rapid test** that can identify individuals who are likely to be infectious and transmit the disease. - Under RNTCP guidelines, this remained the cornerstone diagnostic approach for widespread case finding. *Sputum culture* - While **sputum culture** is the **gold standard** for TB diagnosis due to its higher sensitivity, it is more time-consuming (weeks) and expensive, and thus was not used for initial widespread case finding in RNTCP settings. - It is mainly employed for **drug susceptibility testing (DST)** and in cases where microscopy is negative but TB is strongly suspected. *X-ray chest* - **Chest X-ray** can indicate lung abnormalities consistent with TB, but it is **not specific for active TB infection** and cannot confirm the presence of Mycobacterium tuberculosis. - It is used as a **screening tool** or to assess the extent of disease, but requires further microbiological confirmation for diagnosis. *Mantoux test* - The **Mantoux test** (tuberculin skin test) indicates **TB exposure or latent TB infection**, not active disease, and is not a case-finding tool for active TB patients. **Note:** Under the current **National Tuberculosis Elimination Programme (NTEP)**, which succeeded RNTCP, **CBNAAT/GeneXpert** (a molecular PCR-based test) has become the first-line diagnostic test for all presumptive TB cases, representing a shift from sputum microscopy to universal drug susceptibility testing.

Q: Tetracycline ointment concentration recommended for mass prophylaxis in trachoma control programs is:

1%. ***1% (Correct Answer)*** - **Tetracycline 1% ophthalmic ointment** is the WHO-recommended standard concentration for mass prophylaxis in trachoma control programs [1] - Effective in reducing the prevalence of ocular *Chlamydia trachomatis* infection in endemic areas [1] - Part of the SAFE strategy (Surgery, Antibiotics, Facial cleanliness, Environmental improvement) for trachoma elimination *5% (Incorrect)* - This concentration is **not the recommended standard** for mass prophylaxis of trachoma - Higher concentrations are typically unnecessary and could potentially increase the risk of local irritation without providing significant additional benefit - No evidence supporting superiority over the 1% formulation *0.10% (Incorrect)* - This concentration would be **too low** for effective mass prophylaxis of trachoma - Insufficient to achieve therapeutic levels needed to eliminate *Chlamydia trachomatis* in a population - Would not meet WHO guidelines for trachoma control *0.50% (Incorrect)* - This concentration is **lower than the recommended 1%** for mass prophylaxis - While it might have some activity, it is considered **suboptimal** for achieving population-level control of trachoma - Not supported by evidence-based guidelines for trachoma elimination programs

Q: Every TB sputum positive patient can infect up to

10-15 persons per year. ***10-15 persons per year*** - Each **sputum smear-positive** tuberculosis patient can infect a substantial number of close contacts annually due to the highly contagious nature of **Mycobacterium tuberculosis** via airborne transmission. - This high infectivity rate underscores the importance of prompt diagnosis and treatment to limit disease spread in the community. *1-2 persons per year* - This number is significantly **too low** for a sputum-positive TB patient, who is actively shedding viable bacilli and poses a much higher risk of transmission. - Such a low rate might be associated with less contagious forms of TB, but not sputum-positive pulmonary TB. *5-6 persons per year* - While higher than 1-2, this number still **underestimates the typical infectivity** of an active, sputum-positive TB case. - The potential for infection is greater, especially in conditions of close contact and poor ventilation. *100-200 persons per year* - This figure represents an **overestimation** of the average number of people infected by a single TB patient. - While TB can spread rapidly in specific high-risk settings, such a high general transmission rate is not commonly observed.

Q: Which of the following is/are objectives of the Roll Back Malaria program?

All of the above. ***All of the above*** - The **Roll Back Malaria Partnership (RBM)** is a comprehensive global initiative launched in 1998 to coordinate international action against malaria. - The program adopts a **multi-faceted approach** that includes all three strategies: promoting development of **new treatments and vaccines**, expanding the use of **insecticide-treated mosquito nets (ITNs)**, and empowering **community health workers** for early diagnosis and treatment. - All the listed options represent core pillars of the RBM strategy, making this the correct answer. *Encourage the development of more effective and new anti malarial drugs and vaccines* - This is indeed one component of the RBM program's strategy, focusing on **research and development**. - However, this alone does not encompass the entire program's scope. *Encourage the proper and expanded use of insecticide treated mosquito nets* - This is a critical **vector control intervention** promoted by RBM to reduce mosquito bites and prevent transmission. - While essential, it represents only one pillar of the comprehensive program. *Training of village health workers and mothers on early and appropriate treatment of malaria* - This aspect emphasizes **community engagement** and capacity building for timely diagnosis and case management. - It falls under improving **access to treatment** and strengthening healthcare systems, but is not the entirety of the program.

Q: Which of the following diseases is cyclopropagative?

Malaria. ***Malaria*** - **Malaria** is a **cyclopropagative** disease because the causative agent, *Plasmodium* parasites, undergoes both **cyclical development** and **multiplication** within the mosquito vector. - The parasite's life cycle in the **Anopheles mosquito** involves sexual reproduction (sporogony) and asexual reproduction, leading to an increased number of infective stages (sporozoites). *Filaria* - **Filaria** is a **cyclodevelopmental** disease, meaning the parasitic worms (nematodes) develop cyclically within the vector (e.g., mosquito, blackfly) but **do not multiply** in number. - The vector transmits the microfilariae, which then mature within the human host, but the number of parasites in the vector remains stable, making it non-propagative. *Plague* - **Plague** is caused by the bacterium *Yersinia pestis* and is transmitted by fleas, but it is not a cyclopropagative disease. - While the bacteria multiply within the flea, this transmission is primarily **mechanical** or via a blocked flea foregut, rather than undergoing a complex developmental cycle with propagation like *Plasmodium*. *None of the options* - This option is incorrect because **malaria** clearly fits the definition of a **cyclopropagative disease** due to the multiplication and cyclical development of *Plasmodium* in its vector.

Q: Which of the following vectors is responsible for the highest burden of vector-borne diseases globally?

Mosquito. ***Correct: Mosquito*** - **Mosquitoes** are responsible for transmitting a wide array of devastating diseases, including **malaria**, **dengue**, **Zika virus**, **chikungunya**, **yellow fever**, **Japanese encephalitis**, and **lymphatic filariasis**, leading to hundreds of millions of infections and hundreds of thousands of deaths annually. - Their global distribution, high reproductive rate, and ability to adapt to diverse environments contribute to their significant impact on public health worldwide. - Malaria alone causes over 200 million cases and approximately 600,000 deaths per year, making mosquitoes the deadliest vector globally. *Incorrect: Sand flea* - **Sand fleas** (Tunga penetrans) are responsible for **tungiasis**, a parasitic skin condition, primarily in disadvantaged communities in tropical and subtropical regions. - While it causes significant morbidity and disability, it does not exert the same global burden in terms of mortality and widespread disease outbreaks as mosquito-borne illnesses. *Incorrect: House fly* - **House flies** (Musca domestica) can mechanically transmit various pathogens, including bacteria (e.g., Shigella, Salmonella) and viruses, contributing to gastrointestinal infections. - However, they act primarily as **mechanical vectors** and are not responsible for the direct transmission of dedicated vector-borne diseases with the same catastrophic global impact as mosquitoes. *Incorrect: Mite* - **Mites** are vectors for diseases such as **scrub typhus** (chigger mites) and can cause or transmit conditions like **scabies**. - While these diseases pose localized public health challenges, their global disease burden is considerably lower compared to mosquito-borne diseases.

Q: False about Japanese encephalitis:

Man to Man transmission. ***Man to Man transmission*** - Japanese encephalitis is a **zoonotic disease** primarily transmitted between animals (especially pigs and birds) and mosquitoes. - Humans are considered **dead-end hosts**, meaning they do not develop a high enough viral load in their blood to infect mosquitoes, thus preventing direct human-to-human transmission. *Case fatality rate is about 20-40%* - The **case fatality rate** for Japanese encephalitis is indeed high, typically ranging from 20% to 30%, but can be up to 40% in some outbreaks. - This makes the statement **true**, as it accurately reflects the severe prognosis of the disease. *Pigs are amplifier hosts* - **Pigs** play a crucial role as **amplifier hosts** in the Japanese encephalitis transmission cycle. - They become highly viremic and thus significantly increase the amount of virus circulating in the environment, which can then be picked up by mosquitoes. *Culicine mosquitoes are vectors* - **Culicine mosquitoes**, particularly *Culex tritaeniorhynchus*, are the primary vectors responsible for transmitting the Japanese encephalitis virus. - These mosquitoes typically breed in **rice paddies** and other agricultural areas.

Q: True about influenza -

Most infections are subclinical. **Most infections are subclinical** - Many individuals infected with influenza virus experience **mild symptoms** or no symptoms at all, making the infection subclinical. - This characteristic contributes significantly to the **spread of the virus**, as asymptomatic carriers can unknowingly transmit it. *Incubation period 2-3 weeks* - The typical incubation period for influenza is much shorter, usually **1 to 4 days**, with an average of 2 days [1]. - An incubation period of 2-3 weeks would be more characteristic of other viral infections, such as **chickenpox** or **measles**. *Pandemic is caused by Type-B virus* - **Influenza A virus** is primarily responsible for pandemics due to its ability to undergo both **antigenic drift** and **antigenic shift**, leading to novel viral strains that can spread globally [1]. - Influenza B viruses primarily cause **seasonal epidemics**, often affecting children more severely, and do not typically cause pandemics. *Type-A virus causes Reye's syndrome* - Reye's syndrome is a rare but severe condition associated with the use of **aspirin** (salicylates) in children recovering from certain viral infections, including **influenza A or B** and **chickenpox**. - It is not directly caused by the influenza virus itself but is a medication-related complication in the context of a viral infection, making aspirin use a contraindication in pediatric viral illnesses.

Q: KFD is transmitted by:

Tick. ***Tick*** - KFD, or **Kyasanur Forest Disease**, is a viral hemorrhagic fever endemic to India that is primarily transmitted by infected **ticks**, specifically *Haemaphysalis spinigera*. - Humans can contract the disease through a **tick bite** or contact with an **infected animal**, such as monkeys, which are reservoirs for the virus. *Sandfly* - **Sandflies** are vectors for diseases such as **leishmaniasis** and **bartonellosis**, not Kyasanur Forest Disease. - These insects transmit parasites or bacteria, whereas KFD is a **viral infection** transmitted by ticks. *Mosquito* - **Mosquitoes** are common vectors for many viral diseases, including **dengue**, **malaria**, and **chikungunya**, but they do not transmit Kyasanur Forest Disease. - KFD is exclusively associated with **tick transmission** in its endemic regions. *Mite* - **Mites** can transmit diseases like **scrub typhus** (via chiggers) or cause conditions like **scabies**, but they are not vectors for Kyasanur Forest Disease. - The primary vector for KFD is the **hard tick**.

Question 1

Which Anopheles species is commonly found in urban areas?

Accepted Answer

Anopheles stephensi

Answer

None of the options

Answer

Anopheles fluviatilis

Answer

Anopheles culicifacies

Question 2

Case finding in RNTCP is based on -

Accepted Answer

Sputum microscopy

Answer

Sputum culture

Answer

X-ray chest

Answer

Mantoux test

Question 3

Tetracycline ointment concentration recommended for mass prophylaxis in trachoma control programs is:

Accepted Answer

1%

Answer

5%

Answer

0.10%

Answer

0.50%

Question 4

Every TB sputum positive patient can infect up to

Accepted Answer

10-15 persons per year

Answer

1-2 persons per year

Answer

5-6 persons per year

Answer

100-200 persons per year

Question 5

Which of the following is/are objectives of the Roll Back Malaria program?

Accepted Answer

All of the above

Answer

Encourage the development of more effective and new anti malarial drugs and vaccines

Answer

Encourage the proper and expanded use of insecticide treated mosquito nets

Answer

Training of village health workers and mothers on early and appropriate treatment of malaria

Question 6

Which of the following diseases is cyclopropagative?

Accepted Answer

Malaria

Answer

Filaria

Answer

Plague

Answer

None of the options

Question 7

Which of the following vectors is responsible for the highest burden of vector-borne diseases globally?

Accepted Answer

Mosquito

Answer

Sand flea

Answer

House fly

Answer

Mite

Question 8

False about Japanese encephalitis:

Accepted Answer

Man to Man transmission

Answer

Case fatality rate is about 20-40%

Answer

Pigs are amplifier hosts

Answer

Culicine mosquitoes are vectors

Question 9

True about influenza -

Accepted Answer

Most infections are subclinical

Answer

Incubation period 2-3 weeks

Answer

Pandemic is caused by Type-B virus

Answer

Type-A virus causes Reye's syndrome

Question 10

KFD is transmitted by:

Accepted Answer

Tick

Answer

Sandfly

Answer

Mosquito

Answer

Mite

Infectious Diseases — MCQs

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