Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 311: Zoonotic disease of viral etiology includes -

A. Q fever
B. Rickettsial disease
C. Rubella
D. Rabies (Correct Answer)

Explanation: ***Rabies*** - Rabies is a classic example of a **zoonotic disease** caused by the **rabies virus**, transmitted to humans primarily through the bite of an infected animal. - The virus affects the **central nervous system** and is almost invariably fatal once clinical symptoms appear. *Q fever* - Q fever is a **zoonotic disease**, but it is caused by the bacterium **Coxiella burnetii**, not a virus. - It is often transmitted from farm animals and can cause acute or chronic illness. *Rickettsial disease* - Rickettsial diseases are caused by various species of **Rickettsia bacteria**, which are spread by arthropod vectors like ticks, fleas, and lice. - These are bacterial infections and not viral in origin. *Rubella* - Rubella, also known as German measles, is a **viral disease** caused by the rubella virus, but it is typically spread directly from person to person through respiratory droplets. - It is **not considered a zoonotic disease** as it does not primarily originate in animals and transmit to humans.

Question 312: Safe injection strategy will reduce the occurrence of:

A. Hepatitis E
B. Hepatitis A
C. Hepatitis B (Correct Answer)
D. Typhoid

Explanation: ***Hepatitis B*** - **Hepatitis B** is a blood-borne virus commonly transmitted through contaminated needles and syringes. - Implementing **safe injection strategies**, such as using sterile equipment and proper disposal, effectively reduces its transmission. *Hepatitis E* - **Hepatitis E** is primarily transmitted via the **fecal-oral route**, often through contaminated water. - It is not typically associated with unsafe injection practices. *Hepatitis A* - **Hepatitis A** is also spread primarily through the **fecal-oral route**, often from contaminated food or water. - It has no significant link to injection safety practices. *Typhoid* - **Typhoid fever** is caused by *Salmonella Typhi* and is transmitted through the **ingestion of contaminated food or water**. - Injection practices do not play a role in its transmission.

Question 313: Mass treatment strategy is for treating -

A. Cholera
B. Plague
C. Filariasis (Correct Answer)
D. Diphtheria

Explanation: ***Filariasis*** - **Mass drug administration (MDA)** is a key strategy for the elimination of lymphatic filariasis globally, aiming to treat entire populations in affected areas. - This approach interrupts the transmission cycle by reducing the parasite load in infected individuals, even those without overt symptoms. *Cholera* - Management of cholera primarily involves **rehydration therapy** and, for severe cases, **antibiotics** administered to symptomatic individuals. - While rapid response is crucial, mass treatment of entire populations is not the standard approach for cholera control. *Plague* - Treatment for plague involves **antibiotics** given to individuals suspected or confirmed to have the infection, or for post-exposure prophylaxis in close contacts. - Mass treatment strategies are not typically employed for plague, as it usually presents as localized outbreaks rather than widespread endemic disease suitable for MDA. *Diphtheria* - Treatment for diphtheria focuses on **antitoxin administration** and **antibiotics** to neutralize toxins and eliminate bacteria in infected patients. - Prevention is primarily through **vaccination**, and mass treatment is not a strategy used for diphtheria control.

Question 314: In Roll Back Malaria program, which of the following is not a component?

A. Strengthening health system
B. Developing newer insecticides (Correct Answer)
C. Training for health care workers
D. Using Insecticide-treated bednets

Explanation: ***Developing newer insecticides*** - The Roll Back Malaria (RBM) program focuses on implementing existing and proven interventions for malaria control and elimination, rather than **research and development** of new tools. - While insecticide resistance is a concern, the RBM partnership's primary role is scaling up current effective tools like **insecticide-treated nets** and **indoor residual spraying**. *Strengthening health system* - This is a core component of RBM, as a strong health system is crucial for **effective malaria prevention**, diagnosis, and treatment delivery. - It ensures that interventions reach the population and are **sustainable** in the long term. *Training for health care worker* - **Capacity building** through training of healthcare workers is vital for accurate diagnosis, appropriate treatment, and community engagement in malaria control. - Well-trained staff are essential for the successful implementation of malaria programs, including case management and **data collection**. *Using Insecticide-treated bednets* - **Insecticide-treated bednets (ITNs)** are a cornerstone of malaria prevention efforts endorsed by the RBM partnership. - They provide a **physical and chemical barrier** against mosquito bites, significantly reducing malaria transmission.

Question 315: A dentist suffered from Hepatitis B infection 3 months back. His liver function tests are normal, but HBsAg remains positive and he is not allowed by the medical board to do surgical practice. He is:

A. Inactive carrier
B. Healthy carrier (Correct Answer)
C. Convalescent carrier
D. Paradoxical carrier

Explanation: ***Healthy carrier*** - A **healthy carrier** is an asymptomatic individual who harbors and can transmit the infectious agent while appearing clinically well with **normal liver function tests**. - The dentist has **recovered clinically** (normal LFTs) but remains **HBsAg positive at 3 months**, making him infectious and capable of transmitting hepatitis B to patients during exposure-prone procedures. - This is the **appropriate classification** for someone who is asymptomatic with persistent HBsAg beyond the acute phase but before the 6-month mark that defines chronic infection. - The **practice restriction** is justified because healthy carriers pose a **transmission risk** in surgical and dental procedures involving blood exposure. *Inactive carrier* - An **inactive carrier** (or inactive chronic HBsAg carrier) is a more specific term for individuals with **chronic HBV infection** (HBsAg positive >6 months) who have minimal viral replication, normal ALT, and low/undetectable HBV DNA. - At **3 months post-infection**, chronic carrier state cannot yet be definitively diagnosed as chronicity requires **persistence beyond 6 months**. - While this patient may eventually become an inactive carrier, at 3 months the broader term "healthy carrier" is more appropriate. *Convalescent carrier* - A **convalescent carrier** harbors and sheds pathogens during the **immediate recovery phase** of acute illness, typically for **days to a few weeks**. - At **3 months post-infection**, the patient is well beyond the convalescent period and has entered a **persistent carrier state** rather than active convalescence. - This term is too time-limited to accurately describe someone with **persistent HBsAg at 3 months**. *Paradoxical carrier* - The term **paradoxical carrier** is **not a recognized classification** in hepatitis B epidemiology or standard infectious disease carrier state terminology. - It does not appear in authoritative texts on **viral hepatitis** or carrier state definitions.

Question 316: For yellow fever control, the distance around an airport to be kept free of Aedes breeding is

A. 450m
B. 400m (Correct Answer)
C. 250m
D. 200m

Explanation: ***400m*** - The **International Health Regulations (IHR)** mandate that an area within **400 meters** of an airport in a yellow fever endemic zone must be kept free of *Aedes* breeding sites. - This distance is based on the flight range of the mosquito vector, *Aedes aegypti*, which is approximately **400 meters**. *450m* - This distance is **greater than the recommended** safe zone for *Aedes* breeding site control around airports. - While it would increase safety, it is **not the officially specified** requirement by international health organizations. *250m* - This distance is **insufficient** to ensure an adequate buffer zone against the spread of *Aedes* mosquitoes from breeding sites to aircraft or personnel. - The typical flight range of *Aedes aegypti* extends beyond **250 meters**, making this option unsafe. *200m* - A **200-meter radius** is significantly **too small** to effectively prevent the transmission of yellow fever via *Aedes* mosquitoes around airports. - This limited range would leave a large portion of the mosquito's flight range uncovered, posing a high risk.

Question 317: Plague is transmitted by the bite of -

A. Rat flea (Correct Answer)
B. Tse-Tse fly
C. Culex mosquito
D. Body louse

Explanation: **Correct Answer: Rat flea** - Plague, caused by the bacterium *Yersinia pestis*, is primarily transmitted to humans through the bite of an infected **rat flea** (most commonly *Xenopsylla cheopis*) - The fleas acquire the bacteria by feeding on infected rodents and then transmit it to humans when they bite *Incorrect: Tse-Tse fly* - The **Tse-Tse fly** is the primary vector for **African trypanosomiasis** (sleeping sickness), caused by species of *Trypanosoma* - This fly is not associated with the transmission of plague *Incorrect: Culex mosquito* - The **Culex mosquito** is known to transmit several diseases, including **West Nile virus**, **Japanese encephalitis**, and **filariasis** - It is not a vector for the plague bacterium *Yersinia pestis* *Incorrect: Body louse* - The **body louse** (*Pediculus humanus corporis*) is a vector for diseases such as **epidemic typhus** (caused by *Rickettsia prowazekii*) and **relapsing fever** (caused by *Borrella recurrentis*) - It does not transmit plague

Question 318: Which one of the following is not a strategy under Roll Back Malaria?

A. Anti-larval measures
B. Development of new antimalarial drugs (Correct Answer)
C. Strengthening of health system
D. Use of insecticide treated bed nets

Explanation: ***Development of new antimalarial drugs*** - While research and development of antimalarial drugs is important for global malaria control, it is **NOT one of the core strategic pillars** of the Roll Back Malaria (RBM) partnership - RBM focuses on **implementing existing interventions** rather than drug development, which falls under research organizations like MMV (Medicines for Malaria Venture) - The RBM partnership emphasizes **access to and quality of existing treatments** rather than development of new drugs *Anti-larval measures* - Anti-larval measures (larvicides, environmental management, source reduction) are part of **integrated vector management (IVM)** strategies - While not explicitly listed as one of the four main pillars, they are included under broader vector control approaches alongside ITNs and IRS - These measures complement the prevention strategies promoted by RBM *Strengthening of health system* - This is a **core strategic component** of Roll Back Malaria, essential for effective delivery of malaria interventions - Strong health systems ensure prompt diagnosis, treatment access, commodity supply chains, and surveillance - Health system strengthening enables sustainable malaria control programs *Use of insecticide treated bed nets* - This is a **primary prevention strategy** and core pillar of the Roll Back Malaria partnership - **ITNs (Insecticide Treated Nets)** are highly effective in reducing malaria transmission by protecting individuals from mosquito bites - Mass distribution of ITNs is one of the most successful RBM interventions in endemic areas

Question 319: Infective period of chicken pox is

A. 2 days before and 5 days after rash appearance (Correct Answer)
B. 4 days before and 5 days after rash appearance
C. 4 days before and 4 days after rash appearance
D. 2 days before and 2 days after rash appearance

Explanation: ***2 days before and 5 days after rash appearance*** - The **infective period** for **chickenpox (varicella)** begins approximately **1-2 days before the rash appears** and continues until **all lesions have crusted over**, which typically occurs around **5-7 days after rash onset**. - According to **CDC guidelines** and standard medical references, patients are contagious from 1-2 days prior to rash onset until all vesicles are scabbed. - The timeframe of **2 days before and 5 days after** represents the **clinically accepted standard** for isolation and infection control purposes. *4 days before and 5 days after rash appearance* - This option **overestimates the start of the infective period**. - The incubation period of chickenpox is 10-21 days, but **infectivity does not begin 4 days before rash** - it starts only 1-2 days prior. - This extended timeframe is not supported by standard medical literature. *4 days before and 4 days after rash appearance* - This option **overestimates when infectivity begins** and **underestimates the duration after rash onset**. - Infectivity starts 1-2 days before rash, not 4 days before. - The period after rash onset should extend until all lesions are crusted (typically 5-7 days). *2 days before and 2 days after rash appearance* - While this option correctly identifies when infectivity begins, it **significantly underestimates the duration after rash onset**. - Patients remain contagious until **all lesions have crusted over**, which usually takes **5-7 days** after rash appearance, not just 2 days. - Premature discontinuation of isolation at 2 days would pose significant infection control risks.

Question 320: 'S-A-F-E program' was initiated for the control of which of the following conditions?

A. Ocular trauma
B. Onchocerciasis
C. Refractive error
D. Trachoma (Correct Answer)

Explanation: ***Trachoma*** - The **S-A-F-E program** is a comprehensive strategy developed by the World Health Organization (WHO) for the elimination of blinding **trachoma**. - **S-A-F-E** stands for **Surgery** for trichiasis, **Antibiotics** for infection, **Facial cleanliness**, and **Environmental improvement**. *Ocular trauma* - While ocular trauma is a significant cause of vision impairment, its control and prevention strategies are distinct from the specific interventions of the SAFE program. - Management of ocular trauma focuses on immediate medical attention, surgical repair, and preventive measures like protective eyewear. *Onchocerciasis* - **Onchocerciasis**, also known as river blindness, is controlled primarily through mass drug administration of **ivermectin**, alongside vector control. - This condition is caused by a parasitic worm (**Onchocerca volvulus**) and is not targeted by the SAFE program. *Refractive error* - **Refractive errors** (e.g., myopia, hyperopia, astigmatism) are corrected with spectacles, contact lenses, or refractive surgery. - They are not infectious diseases and do not require the public health interventions outlined in the SAFE program.

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