Infectious Diseases Practice Questions

Q: Mass treatment of trachoma is undertaken if the prevalence of active trachoma (TF), in children aged 1-9 years, is:

5%. ***5%*** - Mass treatment (antibiotic distribution) for trachoma is recommended when the prevalence of **TF (trachomatous inflammation—follicular)** in children aged 1-9 years is **≥5%**. - This threshold is part of the **WHO SAFE strategy** (Surgery, Antibiotics, Facial cleanliness, Environmental improvement) for trachoma elimination. - At this prevalence level, **community-wide mass drug administration (MDA)** with azithromycin is indicated. *6%* - While 6% would definitely trigger mass treatment, the **minimum threshold** established by WHO for initiating antibiotic MDA is **5%**. - This option is above the action threshold but not the specific lower limit defined in guidelines. *3%* - A prevalence of 3% is **below the WHO threshold** for implementing mass antibiotic treatment. - At this level, other components of the **SAFE strategy** (facial cleanliness, environmental improvements) are emphasized, with targeted rather than mass treatment. *10%* - A 10% prevalence is well above the required threshold and would definitely warrant mass treatment, but the question asks for the **minimum threshold**, which is **5%**. - This indicates a **high disease burden** requiring intensive intervention beyond the minimum cutoff.

Q: Chikungunya is transmitted by

Aedes. ***Aedes*** - **Chikungunya virus** is primarily transmitted to humans through the bites of infected **Aedes aegypti** and **Aedes albopictus** mosquitoes. - These mosquitoes are characterized by their **daytime biting** habits and often breed in **domestic water containers**. *Anopheles* - **Anopheles mosquitoes** are the primary vectors for **malaria**, transmitting **Plasmodium parasites**. - They are generally more active during **dusk and dawn** and are not known to transmit chikungunya. *Mansonia* - **Mansonia mosquitoes** are known vectors for certain types of **filariasis** (e.g., Brugian filariasis) and some arboviruses, but not chikungunya. - They are distinctive for their larvae attaching to and obtaining oxygen from the **roots of aquatic plants**. *Culex* - **Culex mosquitoes** are significant vectors for a variety of diseases, including **West Nile virus**, **Japanese encephalitis**, and **filariasis**. - While they can transmit a range of arboviruses, they are not the primary vectors for chikungunya.

Q: Louse transmits:

Trench fever. ***Trench fever*** - **Trench fever** is caused by the bacterium *Bartonella quintana*, which is primarily transmitted to humans through the feces of the **body louse** (*Pediculus humanus corporis*). - The louse vector plays a crucial role in spreading the infection, especially in crowded and unsanitary conditions. *Chagas disease* - **Chagas disease** is caused by the parasite *Trypanosoma cruzi* and is transmitted by blood-sucking **reduviid bugs** (also known as "kissing bugs"), not lice. - The parasite is typically transmitted when infected bug feces enter the bite wound or mucous membranes. *Sleeping sickness* - **Sleeping sickness** (African trypanosomiasis) is caused by *Trypanosoma brucei* and is transmitted by the bite of infected **tsetse flies**, not lice. - The tsetse fly injects the parasite into the human host during a blood meal. *Chikungunya fever* - **Chikungunya fever** is a viral disease transmitted to humans by infected **mosquitoes**, primarily *Aedes aegypti* and *Aedes albopictus*, not lice. - The virus is spread when these mosquitoes feed on an infected person and then bite another person.

Q: All are true regarding Japanese encephalitis disease except:

Man acts as reservoir. ***Man acts as reservoir*** - Humans are considered **dead-end hosts** for Japanese encephalitis; they do not develop sufficiently high viremia to transmit the virus back to mosquitoes. - The primary reservoirs for the Japanese encephalitis virus are **pigs** and **wading birds**. *Pig vaccination control transmission* - **Vaccinating pigs** is an effective strategy to control Japanese encephalitis transmission because pigs are significant amplifier hosts, producing high levels of viremia. - By reducing the viral load in the pig population, pig vaccination helps **break the transmission cycle** between mosquitoes and humans. *Vector is Culex vishnui* - The primary vector involved in the transmission of Japanese encephalitis is indeed **Culex mosquitoes**, with **Culex vishnui complex** being a significant group responsible for its spread in many endemic regions. - These mosquitoes primarily breed in **rice paddies** and other stagnant water sources, which are common in areas where the disease is prevalent. *None of the options are true* - This option is incorrect because the statements regarding **pig vaccination** and the **Culex vishnui** vector are true in the context of Japanese encephalitis. - The initial premise that "Man acts as reservoir" is the false statement, making it the correct answer to the "except" question.

Q: SAFE strategy is recommended for-

Trachoma. ***Trachoma*** * The **SAFE strategy (Surgery, Antibiotics, Facial Cleanliness, Environmental improvement)** is the WHO-recommended public health approach for the elimination of **trachoma**, a chronic eye infection caused by *Chlamydia trachomatis*. * This comprehensive strategy addresses both active infection and its blinding sequelae, specifically **trichiasis** (in-turned eyelashes) through surgery. *Diabetic retinopathy* * Management of diabetic retinopathy primarily involves **blood sugar control, regular ophthalmologic exams, laser photocoagulation, and anti-VEGF injections**, not the SAFE strategy. * The focus is on preventing and treating retinal damage caused by **diabetes**, which is distinct from infectious causes. *Glaucoma* * Glaucoma is characterized by **optic nerve damage** and visual field loss, usually due to elevated intraocular pressure, and is managed with **medication, laser therapy, or surgery (e.g., trabeculectomy)**. * It is a **neurodegenerative condition**, not an infectious disease, so the SAFE strategy is not applicable. *Cataract* * Cataracts involve the **clouding of the natural lens** of the eye, leading to blurred vision, and are primarily treated through **surgical removal of the cloudy lens** and implantation of an artificial intraocular lens. * This condition is age-related or can be caused by trauma or disease, but it is **not an infection** for which the SAFE strategy would be relevant.

Q: Vector for Zika virus disease is:

Aedes Aegypti. ***Aedes aegypti*** - The **Aedes aegypti mosquito** is the primary vector responsible for transmitting the Zika virus to humans. - This mosquito species is also known to transmit other arboviruses, including **dengue** and **chikungunya** viruses. *Culex* - **Culex mosquitoes** are known vectors for diseases such as **West Nile virus** and **Japanese encephalitis**. - They are generally not considered primary vectors for the Zika virus. *Phlebotomus* - **Phlebotomus (sandflies)** are vectors for parasitic diseases, most notably **leishmaniasis**. - They are not involved in the transmission of viral infections like Zika. *Anopheles stephensi* - **Anopheles mosquitoes**, particularly *Anopheles stephensi*, are the main vectors for **malaria**. - They do not play a role in the transmission of the Zika virus.

Q: Mass Drug Administration is NOT routinely used as the primary strategy for:

Scabies. ***Scabies*** - While **mass drug administration with oral ivermectin** has shown effectiveness in specific endemic outbreak settings, MDA is generally **not the primary recommended strategy** for routine scabies control in most public health contexts. - Scabies control typically prioritizes **case finding, contact tracing, simultaneous household treatment, and environmental decontamination**—which are more complex to implement than standard MDA programs. - Unlike the other conditions listed, scabies lacks well-established **routine MDA programs** at the scale of national public health initiatives, making it the least suitable option for MDA among these choices. *Vitamin A Deficiency* - **Vitamin A supplementation** through MDA is a **highly effective and widely implemented** WHO-recommended strategy to combat Vitamin A deficiency in at-risk populations, particularly children under 5 years. - Regular mass supplementation helps prevent **xerophthalmia** and reduces morbidity and mortality from infectious diseases. - This is a cornerstone of routine public health programs globally. *Lymphatic Filariasis* - **Lymphatic filariasis** is a classic example where MDA with anti-filarial drugs like **diethylcarbamazine (DEC), albendazole,** or **ivermectin** is the cornerstone strategy for interrupting transmission. - MDA is the **primary WHO-recommended approach** to achieve elimination of lymphatic filariasis, with established national programs in endemic countries. *Worm infestation* - **Mass deworming programs** using drugs like **albendazole** or **mebendazole** represent highly effective and well-established forms of MDA for controlling **soil-transmitted helminth infections**. - These routine programs significantly reduce disease burden in school-aged children, improving nutritional status, growth, and learning outcomes.

Q: Regarding Influenza, which statement is not true?

1-5 years age is not a high risk age group. ***1-5 years age is not a high risk age group*** (This statement is FALSE - making it the correct answer) - Children aged **1-5 years ARE considered a high-risk group** for severe influenza and its complications. - They often require **hospitalization** and may experience complications such as pneumonia, otitis media, and seizures. - This statement is incorrect, which is why it's the answer to "which is NOT true." *Virus shedding present before the patient presents with symptoms* (This statement is TRUE) - Influenza is highly contagious, and patients typically shed the **virus for 1 to 2 days before the onset of symptoms.** - This **presymptomatic shedding** contributes significantly to the rapid spread of the virus. *Aquatic birds are reservoir* (This statement is TRUE) - **Wild aquatic birds** are the natural reservoir for most influenza A viruses, particularly those with a broad range of hemagglutinin (HA) and neuraminidase (NA) subtypes. - They can carry influenza viruses without becoming ill, contributing to the **genetic diversity and evolution of new strains.** *Secondary attack rate 5-15%* (This statement is TRUE) - The **secondary attack rate** for influenza in households and close contacts is typically estimated to be between 5% and 15%. - This rate indicates the **likelihood of transmission** from an infected individual to susceptible household members or close contacts.

Q: A district shows API of 4.2, ABER 11%, and SPR 3.1%. What is the malaria surveillance status?

Adequate surveillance. ***Adequate surveillance*** - An **ABER of 11%** meets the WHO minimum threshold of **≥10%** for adequate malaria surveillance, indicating that blood examination is occurring at an acceptable level. - An **API of 4.2** per 1000 population indicates moderate malaria transmission with reasonable case detection. - An **SPR of 3.1%** is within the acceptable range (1-5%), suggesting balanced testing practices—not excessively high (which would indicate poor case detection) or extremely low (though lower would be better). - Together, these metrics indicate a **functioning surveillance system** that meets basic adequacy criteria but has room for optimization. *Poor surveillance* - This would be characterized by **ABER 10%** (suggesting only highly symptomatic cases are tested), or extremely low reporting rates. - The given values (API 4.2, ABER 11%, SPR 3.1%) do not align with poor surveillance indicators. *Cannot be determined* - The three epidemiological indicators provided (API, ABER, SPR) are **standard WHO metrics** specifically designed to assess malaria surveillance effectiveness. - These metrics provide **sufficient information** to make a determination about surveillance status. *Optimal surveillance* - Optimal surveillance would require **ABER ≥20-50%** (much higher blood examination coverage), **SPR <2%** (indicating highly sensitive early case detection), and comprehensive reporting systems. - While the current ABER of 11% is adequate, it is just above the minimum threshold and would need substantial improvement to reach optimal levels.

Question 1

Mass treatment of trachoma is undertaken if the prevalence of active trachoma (TF), in children aged 1-9 years, is:

Accepted Answer

5%

Answer

6%

Answer

3%

Answer

10%

Question 2

Chikungunya is transmitted by

Accepted Answer

Aedes

Answer

Anopheles

Answer

Mansonia

Answer

Culex

Question 3

Louse transmits:

Accepted Answer

Trench fever

Answer

Chagas disease

Answer

Sleeping sickness

Answer

Chikungunya fever

Question 4

All are true regarding Japanese encephalitis disease except:

Accepted Answer

Man acts as reservoir

Answer

Pig vaccination control transmission

Answer

Vector is Culex vishnui

Answer

None of the options are true

Question 5

SAFE strategy is recommended for-

Accepted Answer

Trachoma

Answer

Diabetic retinopathy

Answer

Glaucoma

Answer

Cataract

Question 6

Vector for Zika virus disease is:

Accepted Answer

Aedes Aegypti

Answer

Culex

Answer

Phlebotomus

Answer

Anopheles stephensi

Question 7

Mass Drug Administration is NOT routinely used as the primary strategy for:

Accepted Answer

Scabies

Answer

Vitamin A Deficiency

Answer

Lymphatic Filariasis

Answer

Worm infestation

Question 8

Regarding Influenza, which statement is not true?

Accepted Answer

1-5 years age is not a high risk age group

Answer

Virus shedding present before the patient presents with symptoms

Answer

Aquatic birds are reservoir

Answer

Secondary attack rate 5-15%

Question 9

A district shows API of 4.2, ABER 11%, and SPR 3.1%. What is the malaria surveillance status?

Accepted Answer

Adequate surveillance

Answer

Poor surveillance

Answer

Cannot be determined

Answer

Optimal surveillance

Question 10

Malaria control means

Accepted Answer

To reduce Malaria disease so that it's no longer a Public Health Problem

Answer

To prevent local transmission for 3 years

Answer

To reduce Incidence to Zero

Answer

To reduce Malaria mortality to Zero

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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