Infectious Diseases Practice Questions

Q: Zoonotic diseases are -

All of the options. ***All of the options*** - **Anthrax**, **Plague**, and **Salmonellosis** are all well-established examples of zoonotic diseases, which are infections naturally transmitted between vertebrate animals and humans. - These diseases represent a diverse spectrum of bacterial infections with significant public health implications worldwide. **Anthrax** - Caused by *Bacillus anthracis*, a spore-forming bacterium naturally found in soil that primarily affects livestock and wild herbivores. - Humans acquire infection through contact with infected animals or contaminated animal products (hides, wool, meat). - Clinical forms include cutaneous (most common), inhalational (most severe), and gastrointestinal anthrax. - Remains an important occupational hazard for veterinarians, farmers, and those handling animal products. **Plague** - Caused by *Yersinia pestis*, maintained in nature through rodent-flea cycles. - Transmission to humans occurs primarily via bites from infected fleas or direct contact with infected animals. - Historically responsible for devastating pandemics including the Black Death. - Clinical manifestations include bubonic (most common), pneumonic (person-to-person transmission possible), and septicemic plague. **Salmonellosis** - Caused by non-typhoidal *Salmonella* species, commonly colonizing the intestines of various animals including poultry, cattle, reptiles, and pets. - Humans typically acquire infection through consumption of contaminated food (undercooked meat, eggs, unpasteurized dairy) or direct animal contact. - Presents as acute gastroenteritis with diarrhea, fever, and abdominal cramps. - One of the most common foodborne zoonotic infections globally.

Q: Which of the following is NOT true about varicella infection?

Only single stage of lesion is present at a time. ***Only single stage of lesion is present at a time*** - This statement is **incorrect** and represents the key distinguishing feature that makes this the answer. - Varicella (chickenpox) is classically characterized by **pleomorphism** - lesions in various stages of development (macules, papules, vesicles, pustules, and crusts) appearing **simultaneously** on the body. - This "multiple stages at once" phenomenon is a pathognomonic diagnostic feature of chickenpox, differentiating it from other vesicular rashes like smallpox (which shows uniform stage lesions). *Lesions occur on flexor surfaces* - This statement is **not a defining characteristic** of varicella, though it is not entirely false either. - Varicella typically has a **centripetal distribution** - lesions predominantly affect the **trunk and face**, with relative sparing of distal extremities. - Unlike conditions such as atopic dermatitis, varicella does **not** have a specific predilection for flexor versus extensor surfaces. - While lesions may appear on flexor areas, they appear throughout the body without preferential flexor involvement, making this statement less accurate than the other options. *Secondary attack rate is 90%* - This statement is **true**. Varicella is highly contagious with an R₀ (basic reproduction number) of 10-12. - The **secondary attack rate** among susceptible household contacts ranges from **80-90%**, making it one of the most contagious viral infections. *Reactivation occurs in 10-30% of cases* - This statement is **true**. After primary varicella infection, varicella-zoster virus (VZV) remains **latent in dorsal root ganglia**. - **Lifetime risk** of reactivation causing **herpes zoster (shingles)** is approximately **10-30%**, increasing with age and immunosuppression.

Q: Which of the following diseases is characterized by propagative transmission?

All of the options. ***All of the options*** **Propagative transmission** is a type of biological transmission where the pathogen undergoes **multiplication and/or development** within the vector before being transmitted to a new host. **All three diseases exhibit propagative transmission:** - ***Plague***: *Yersinia pestis* multiplies extensively in the gut of the flea (*Xenopsylla cheopis*). The bacteria form a biofilm that blocks the proventriculus, causing the flea to regurgitate bacteria into the bite wound during feeding. - ***Malaria***: *Plasmodium* species undergo **sporogony** (sexual reproduction and development) in the *Anopheles* mosquito. The parasite develops from gametocytes → zygote → ookinete → oocyst → sporozoites over 10-14 days. This is **cyclopropagative transmission**. - ***Filaria***: *Wuchereria bancrofti* undergoes larval development in mosquitoes (*Culex* species). The microfilariae develop through three larval stages (L1 → L2 → L3) in the mosquito's thoracic muscles before becoming infective. This is also **cyclopropagative transmission**. **Key Concept**: In propagative transmission, there is an **extrinsic incubation period** during which the pathogen develops in the vector, distinguishing it from mechanical transmission where simple transfer occurs without multiplication or development.

Q: According to WHO guidelines, the minimum recommended denier count for polyethylene mosquito nets (LLINs) for effective malaria prevention is:

150 denier. ***150*** - The World Health Organization (WHO) recommends a minimum of **150 denier polyethylene** or **75 denier polyester** for long-lasting insecticidal nets (LLINs) to ensure durability and effectiveness. - This denier count provides the necessary strength to withstand household conditions and repeated washing over several years without compromising the net's ability to prevent mosquito bites. *250* - While a denier count of **250** would generally indicate a thicker and potentially more durable fabric, it is not the *minimum recommended* by the WHO for effective malaria prevention using LLINs. - Such a high denier count might make the net heavier, more expensive, and potentially reduce breathability without offering significantly greater, WHO-mandated protective benefits over the recommended standard. *350* - A denier count of **350** would result in a very thick and heavy net material, which is well above the minimum recommendation for insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) by the WHO. - While it would be durable, it is not the **most important characteristic** in terms of meeting the fundamental effectiveness guidelines for malaria prevention and might lead to issues like increased cost, reduced airflow, and user discomfort. *100* - A denier count of **100** (for polyethylene) falls below the WHO's recommended minimum denier for long-lasting insecticidal nets (LLINs). - Nets with a lower denier count are generally **less durable** and more prone to tearing, which can compromise their effectiveness in preventing mosquito bites over their intended lifespan.

Q: Hepatitis B infection spreads through all of the following routes except

Fecal-oral route. ***Fecal-oral route*** - **Hepatitis B** is primarily transmitted through contact with infected **blood** or **body fluids**, not via the fecal-oral route. - Diseases spread by the fecal-oral route are typically characterized by poor hygiene and contaminated food or water, which is not the case for Hepatitis B. *Blood transfusion* - Transmission through **blood transfusions** was a significant route before routine screening of blood products for **Hepatitis B surface antigen (HBsAg)** was implemented. - Although rare now in developed countries, it remains a possible route if unscreened blood is used. *Sexual contact* - **Hepatitis B virus (HBV)** is present in **semen** and **vaginal fluids**, making unprotected sexual intercourse a very common mode of transmission. - The risk of transmission increases with the number of partners and certain sexual practices. *Perinatal transmission* - **Perinatal transmission** from an infected mother to her newborn during **childbirth** is a major route of HBV spread, especially in endemic areas. - This can lead to chronic infection in infants if not prevented with immunoprophylaxis.

Q: Which one of the following is an emerging viral disease?

SARS. ***SARS*** - **SARS (Severe Acute Respiratory Syndrome)** emerged in 2002-2003 and caused a global outbreak, making it a classic example of an **emerging viral disease**. - Emerging viral diseases are those that have recently appeared in a population or whose incidence has increased rapidly in recent times. *Measles* - Measles is an **established and re-emerging disease**, meaning it has been present for a long time but has seen resurgence due to factors like declining vaccination rates. - It is caused by the **measles virus (MeV)**, a paramyxovirus, and has been a known human pathogen for centuries. *Chicken pox* - Chickenpox, caused by the **varicella-zoster virus (VZV)**, is a common and well-known childhood disease that has been endemic for a long time. - While it can be severe, it is not considered an emerging disease as its presence and characteristics have been established for many years. *Rabies* - Rabies, caused by the **rabies virus**, is a highly fatal disease primarily transmitted through animal bites and has been recognized globally for centuries. - Although it remains a significant public health concern, it is an **ancient and well-established zoonotic disease**, not an emerging one.

Q: A night blood survey is done in -

Filariasis. ***Filariasis*** - A **night blood survey** is essential for diagnosing filariasis because **microfilariae**, especially *Wuchereria bancrofti* and *Brugia malayi*, exhibit **nocturnal periodicity**, meaning they are most abundant in peripheral blood at night. - This timing optimizes detection and confirms the presence of the parasitic worm larvae. *Malaria* - The diagnosis of malaria involves examining peripheral blood smears for **parasites (plasmodia)**, but screening is typically done at any time, especially during fever spikes. - Unlike filariasis, **malaria parasites** do not show a distinct nocturnal periodicity in the peripheral blood. *Dengue* - Dengue diagnosis relies on detecting the **virus (RNA)**, **viral antigens (NS1)**, or **antibodies (IgM, IgG)** in blood samples, which can be done at any time of the day. - It does not involve a "night blood survey" as the **dengue virus** is continuously present in the blood during the acute phase. *Plague* - Diagnosis of plague involves culturing the **bacterium *Yersinia pestis*** from blood, lymph node aspirates, or sputum, or detecting its antigens. - There is no specific requirement for a **night blood survey** as bacterial load does not exhibit nocturnal periodicity.

Q: Under the WHO "Vision 2020" program, the "SAFE" strategy is adopted for which of the following diseases:

Trachoma. ***Trachoma*** * The SAFE strategy is an acronym for **Surgery** for trichiasis, **Antibiotics** to treat infection (especially azithromycin), **Facial cleanliness**, and **Environmental improvement** to prevent transmission. * This comprehensive approach is central to the global elimination efforts for **trachoma**, as outlined by the WHO's Vision 2020 initiative. *Glaucoma* * Glaucoma management typically involves **medications (eye drops)** to lower intraocular pressure, laser therapy, or **surgery** to improve fluid drainage from the eye. * The SAFE strategy with its specific components (Surgery for trichiasis, Antibiotics, Facial cleanliness, Environmental improvement) is not applicable to the pathophysiology or treatment of **glaucoma**. *Onchocerciasis* * Onchocerciasis, or **river blindness**, is primarily controlled through mass drug administration of **ivermectin** to kill microfilariae and prevent new infections. * While both are Neglected Tropical Diseases causing blindness, the SAFE strategy is not designed for **onchocerciasis** prevention or treatment, which focuses on vector control and anthelmintic drugs. *Diabetic retinopathy* * Management of diabetic retinopathy focuses on **strict glycemic control**, managing blood pressure and lipids, and interventions such as **laser photocoagulation**, intravitreal injections of anti-VEGF agents, or vitrectomy for severe cases. * The term "SAFE strategy" with its specific interventions relates to bacterial infection control and environmental hygiene, which are not primary methods for managing **diabetic retinopathy**.

Q: SET centers are established if the prevalence of leprosy is (per 1000 population):

1–5. ***1–5*** - **SET (Survey, Education, Treatment) centers** are established in areas where the prevalence of leprosy is **1 to 5 cases per 1000 population**. - This prevalence indicates a moderate endemicity, requiring a focused approach for case detection, health education, and timely treatment to control the disease spread. *10* - A prevalence of **10 cases per 1000 population** is considered very high, suggesting a more widespread disease burden that might necessitate broader public health interventions rather than just SET centers. - This level might indicate a need for more intensive screening and mass treatment strategies. *5–10* - A prevalence of **5 to 10 cases per 1000 population** is also relatively high, usually prompting more aggressive control measures beyond the standard SET center approach. - Such high prevalence often points to areas requiring more advanced intervention strategies. *0.5–1* - A prevalence of **0.5 to 1 case per 1000 population** is considered low, indicating that leprosy is nearing elimination as a public health problem. - In such scenarios, integration of leprosy services into general health services or sentinel surveillance might be sufficient, rather than establishing dedicated SET centers.

Q: What is the color of Kit 3 for STD management under the AIDS Control Programme?

Green. ***Green*** - Under the **AIDS Control Programme**, the **National AIDS Control Organization (NACO)** standardizes treatment for STDs using syndromic management kits. - **Kit 3**, designated for the management of **vaginal discharge syndrome** in women, is identified by its **green** color. *Blue* - **Blue** is the color assigned to **Kit 1**, which is used for the syndromic management of **urethral discharge in men**. - This kit focuses on common causes of urethral inflammation and discharge. *White* - **White** is the color for **Kit 4**, which is used for the syndromic management of **genital ulcer disease without inguinal adenopathy**. - This kit often contains treatments for syphilis and chancroid. *Red* - **Red** is the color designated for **Kit 2**, which is used for the syndromic management of **genital ulcer disease with inguinal bubo**. - This kit typically includes treatments for conditions like lymphogranuloma venereum or severe chancroid.

Question 1

Zoonotic diseases are -

Accepted Answer

All of the options

Answer

Anthrax

Answer

Plague

Answer

Salmonellosis

Question 2

Which of the following is NOT true about varicella infection?

Accepted Answer

Only single stage of lesion is present at a time

Answer

Lesions occur on flexor surfaces

Answer

Secondary attack rate is 90%

Answer

Reactivation occurs in 10-30% of cases

Question 3

Which of the following diseases is characterized by propagative transmission?

Accepted Answer

All of the options

Answer

Filaria

Answer

Plague

Answer

Malaria

Question 4

According to WHO guidelines, the minimum recommended denier count for polyethylene mosquito nets (LLINs) for effective malaria prevention is:

Accepted Answer

150 denier

Answer

250 denier

Answer

350 denier

Answer

100 denier

Question 5

Hepatitis B infection spreads through all of the following routes except

Accepted Answer

Fecal-oral route

Answer

Blood transfusion

Answer

Sexual contact

Answer

Perinatal transmission

Question 6

Which one of the following is an emerging viral disease?

Accepted Answer

SARS

Answer

Measles

Answer

Chicken pox

Answer

Rabies

Question 7

A night blood survey is done in -

Accepted Answer

Filariasis

Answer

Malaria

Answer

Dengue

Answer

Plague

Question 8

Under the WHO "Vision 2020" program, the "SAFE" strategy is adopted for which of the following diseases:

Accepted Answer

Trachoma

Answer

Glaucoma

Answer

Onchocerciasis

Answer

Diabetic retinopathy

Question 9

SET centers are established if the prevalence of leprosy is (per 1000 population):

Accepted Answer

1–5

Answer

10

Answer

5–10

Answer

0.5–1

Question 10

What is the color of Kit 3 for STD management under the AIDS Control Programme?

Accepted Answer

Green

Answer

Blue

Answer

White

Answer

Red

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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