Infectious Diseases Practice Questions

Q: A person with tuberculosis on domiciliary treatment is expected to do all, except?

Use separate vessels. ***Use separate vessels*** - **Tuberculosis** is primarily spread through airborne droplets, not through shared utensils. - While good hygiene is important, using separate dishes is not a specific requirement for preventing transmission in a household setting and is not routinely advised. *Collect drugs regularly* - **Regular collection and adherence to drug therapy** are crucial for treatment success and preventing drug resistance in tuberculosis. - Interrupted treatment can lead to **treatment failure** and spread of the disease. *Dispose sputum safely* - **Sputum** from a person with active tuberculosis contains the bacteria and can be a source of airborne transmission. - Proper disposal, such as in a covered container that is then sterilized or discarded safely, helps prevent the spread of infection. *Report to PHC if new symptoms arise* - **Close monitoring** for new or worsening symptoms is essential to identify potential side effects of medication, treatment failure, or development of complications. - Reporting to a **Primary Health Centre (PHC)** ensures timely medical review and management.

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.

Question 1

A person with tuberculosis on domiciliary treatment is expected to do all, except?

Accepted Answer

Use separate vessels

Answer

Collect drugs regularly

Answer

Dispose sputum safely

Answer

Report to PHC if new symptoms arise

Question 2

Zoonotic diseases are -

Accepted Answer

All of the options

Answer

Anthrax

Answer

Plague

Answer

Salmonellosis

Question 3

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 4

Which of the following diseases is characterized by propagative transmission?

Accepted Answer

All of the options

Answer

Filaria

Answer

Plague

Answer

Malaria

Question 5

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 6

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 7

Which one of the following is an emerging viral disease?

Accepted Answer

SARS

Answer

Measles

Answer

Chicken pox

Answer

Rabies

Question 8

A night blood survey is done in -

Accepted Answer

Filariasis

Answer

Malaria

Answer

Dengue

Answer

Plague

Question 9

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 10

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

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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