Infectious Diseases Practice Questions

Q: All of the following are zoonotic infections, except?

HIV. ### Explanation **Correct Answer: C. HIV** **Concept:** A **Zoonosis** is defined by the WHO as an infection or infectious disease transmissible under natural conditions from vertebrate animals to humans. While HIV-1 and HIV-2 originated from cross-species transmission of Simian Immunodeficiency Viruses (SIV) from primates to humans decades ago (a process called *zoonotic spillover*), HIV is now classified as a **human-only infection**. It is maintained in the population through human-to-human transmission (sexual, parenteral, or vertical) and does not require an animal reservoir for its current life cycle. **Analysis of Incorrect Options:** * **A. Plague:** A classic zoonosis caused by *Yersinia pestis*. Its natural reservoir is wild rodents (e.g., Tatera indica), and it is transmitted to humans via the bite of infected rat fleas (*Xenopsylla cheopis*). * **B. Japanese Encephalitis (JE):** An obligate zoonosis. The virus is maintained in an **Enzootic cycle** involving pigs (amplifier hosts) and water birds (ardied birds/reservoirs). Humans are "dead-end hosts." * **D. Tuberculosis:** While *M. tuberculosis* is primarily human, *Mycobacterium bovis* (Bovine TB) is a significant zoonotic pathogen transmitted to humans via unpasteurized milk or direct contact with infected cattle. Therefore, TB is traditionally included in the list of zoonotic infections. **NEET-PG High-Yield Pearls:** * **Dead-end hosts:** Humans are dead-end hosts for JE, Rabies, and Hydatid disease (transmission stops at the human). * **Cyclozoonosis:** Requires more than one vertebrate host to complete the life cycle (e.g., Echinococcosis, Taeniasis). * **Anthropozoonosis:** Infections transmitted from animals to humans (e.g., Rabies, Anthrax). * **Zooanthroponosis:** Infections transmitted from humans to animals (e.g., Human TB to cattle).

Q: What is the primary concern of the District TB Control Programme?

Finding out resistant cases. **Explanation:** The primary concern of the District TB Control Programme (now integrated under the **National TB Elimination Programme - NTEP**) has evolved from simple case detection to addressing the most significant threat to TB control: **Drug Resistance**. **1. Why "Finding out resistant cases" is correct:** While the program aims to eliminate TB, the emergence of Multi-Drug Resistant (MDR-TB) and Extensively Drug-Resistant (XDR-TB) cases poses the greatest public health challenge. Resistant cases act as a reservoir for transmission of difficult-to-treat strains, leading to higher mortality and treatment failure rates. Identifying these cases early through **Universal Drug Susceptibility Testing (UDST)** is the top priority to prevent a "man-made" epidemic of incurable TB. **2. Why other options are incorrect:** * **Option A & C:** Finding new cases and ensuring treatment are fundamental *objectives* of the program. However, in the context of "primary concern" (the most critical challenge or priority), the focus shifts to the quality of the cure and preventing the spread of resistant strains. Simple case detection without addressing resistance leads to poor outcomes. * **Option D:** While all are goals, the specific "concern" or bottleneck in modern TB control is the rising trend of resistance. **High-Yield Clinical Pearls for NEET-PG:** * **NTEP Goal:** To achieve a "TB Free India" by **2025** (5 years ahead of the Global SDG target of 2030). * **UDST:** Under NTEP, every diagnosed TB patient must undergo Drug Susceptibility Testing at the time of diagnosis to rule out Rifampicin resistance. * **Diagnostic Tool of Choice:** **CBNAAT** (GeneXpert) or **Truenat** are now the preferred initial tests over sputum microscopy to identify resistance early. * **Nikshay:** The web-based portal used for monitoring TB patients and resistance patterns in India.

Q: Which of the following statements about chickenpox is false?

The secondary attack rate is approximately 60%.. **Explanation:** The correct answer is **C** because the statement is factually incorrect. Chickenpox is highly contagious, and its **Secondary Attack Rate (SAR)** in household contacts is approximately **90%**, not 60%. A SAR of 90% indicates that nearly every susceptible individual in a household will contract the disease following exposure to a primary case. **Analysis of other options:** * **Option A (True):** Chickenpox is caused by the **Varicella-Zoster Virus (VZV)**, a DNA virus belonging to the Herpesviridae family (Human Herpesvirus 3). * **Option B (True):** The incubation period typically ranges from 10 to 21 days, with **14–16 days** being the most common average. * **Option D (True):** The rash of chickenpox is **centripetal** in distribution (more on the trunk, less on the limbs) and characteristically **spares the palms and soles**. This is a key clinical differentiator from Smallpox, where the rash is centrifugal and involves the palms and soles. **High-Yield Clinical Pearls for NEET-PG:** * **Period of Communicability:** From 1–2 days *before* the appearance of the rash until all lesions have crusted (usually 6 days after onset). * **Pleomorphism:** This is the hallmark of chickenpox, where all stages of the rash (papules, vesicles, and crusts) are visible simultaneously in the same area. * **Dew-drop on a rose petal:** Classic description of the clear, thin-walled vesicles. * **Congenital Varicella Syndrome:** Highest risk occurs if the mother is infected between 8–20 weeks of gestation. * **Shingles (Herpes Zoster):** Represents the reactivation of the latent VZV in the dorsal root ganglia.

Q: What is/are true regarding the management of a rat bite?

Rarely need rabies immunoglobulin. **Explanation:** The management of rat bites is a frequent point of confusion in medical exams. The core concept to understand is that **small rodents (rats, mice, squirrels, hamsters) are not known to transmit rabies to humans.** **1. Why Option C is Correct:** According to the **WHO and National Guidelines on Rabies Prophylaxis**, small rodents are generally considered "low-risk" or "no-risk" for rabies. While they can theoretically be infected, they usually die from the predator's bite before they can transmit the virus. Therefore, **Post-Exposure Prophylaxis (PEP), including Rabies Immunoglobulin (RIG) and the Rabies Vaccine, is not routinely recommended** for rat bites. RIG is "rarely" needed unless the animal was confirmed to be rabid or showed highly unusual behavior in an endemic area. **2. Why Other Options are Incorrect:** * **Option A:** Routine vaccination with ARV is not indicated for rat bites for the reasons mentioned above. * **Option B:** While Tetanus Toxoid (TT) is part of general wound management, it is not the *defining* or most specific management priority unique to the clinical dilemma of "rabies vs. no rabies" in rat bites. * **Option D:** Washing with soap and water is standard for any wound, but in the context of this specific question, the examiner is testing your knowledge of rabies protocol. **High-Yield Clinical Pearls for NEET-PG:** * **Rat-Bite Fever:** The primary concern in rat bites is not rabies, but infections caused by *Streptobacillus moniliformis* or *Spirillum minus*. * **Rabies-Free Animals:** Bites from rabbits, hares, and small rodents do **not** require rabies PEP. * **Treatment of Choice:** For Rat-Bite Fever, the drug of choice is **Penicillin G**. * **Category III Bites:** For high-risk animals (dogs, cats, monkeys), RIG is mandatory for all Category III exposures. For rats, it is omitted.

Q: Which of the following has the least chance of transmitting HIV infection?

Heterosexual intercourse. ### Explanation The risk of HIV transmission varies significantly depending on the route of exposure and the viral load of the source. This question asks for the **least** efficient mode of transmission among the given options. **1. Why Heterosexual Intercourse is the Correct Answer:** While heterosexual intercourse is the most common mode of transmission globally due to the sheer frequency of the act, it has the **lowest per-act risk** (approximately 0.04% to 0.1% for females and 0.04% for males). The low efficiency is due to the mucosal barrier and the relatively low concentration of the virus in vaginal or seminal fluids compared to whole blood. **2. Analysis of Incorrect Options:** * **Blood Transfusion:** This is the **most efficient** mode of transmission. A single unit of HIV-infected blood carries a transmission risk of approximately **90-95%**. * **Vertical Transmission:** Without intervention, the risk of mother-to-child transmission (MTCT) is about **20-45%**. With modern ART and PMTCT protocols, this can be reduced to Vertical (30%) > Needle prick (0.3%) > Receptive Anal Sex (1.38%) > Receptive Vaginal Sex (0.08%). * **Most Common Route:** Globally and in India, **Heterosexual transmission** is the most common route. * **Window Period:** Usually 2–12 weeks; the best screening test is **4th Gen ELISA** (detects p24 antigen + antibodies). * **Post-Exposure Prophylaxis (PEP):** Must be started within **72 hours** (ideally within 2 hours) and continued for **28 days**.

Q: Which of the following is excluded from the National Vector Borne Disease Control Programme (NVBDCP)?

Kyasanur Forest Disease (KFD). **Explanation:** The **National Vector Borne Disease Control Programme (NVBDCP)**, now subsumed under the National Center for Vector Borne Diseases Control (NCVBDC), is an umbrella programme in India targeting specific vector-borne diseases of public health importance. **Why Kyasanur Forest Disease (KFD) is the correct answer:** KFD, also known as "Monkey Fever," is a tick-borne viral hemorrhagic fever primarily localized to specific districts in Karnataka and neighboring states. While it is a vector-borne disease, it is **not** included under the NVBDCP. It is instead monitored under the Integrated Disease Surveillance Programme (IDSP) due to its localized geographical distribution. **Analysis of Incorrect Options:** The NVBDCP currently covers **six** specific diseases: * **A. Malaria:** Transmitted by the *Anopheles* mosquito; it is the primary focus of the programme. * **B. Filariasis:** Transmitted by *Culex* mosquitoes; the programme aims for elimination through Mass Drug Administration (MDA). * **C. Kala-azar (Visceral Leishmaniasis):** Transmitted by the Sandfly (*Phlebotomus argentipes*); targeted for elimination in endemic states (Bihar, Jharkhand, UP, West Bengal). * *Note: The remaining three diseases under NVBDCP are **Dengue, Chikungunya, and Japanese Encephalitis.*** **High-Yield Clinical Pearls for NEET-PG:** * **The "Big 6":** Remember the mnemonic **"MD-KFC-J"** (Malaria, Dengue, Kala-azar, Filariasis, Chikungunya, Japanese Encephalitis). * **Elimination Targets:** India aims to eliminate Malaria by 2030 and Lymphatic Filariasis/Kala-azar in the near future. * **KFD Vector:** The principal vector for KFD is the hard tick (*Haemaphysalis spinigera*). * **KFD Vaccine:** Unlike most NVBDCP diseases, a formal killed vaccine exists for KFD (though its efficacy is debated).

Q: Under the Enhanced Malaria Control Programme (EMCP) launched in 1997, which of the following was NOT a criterion for the selection of Primary Health Centres (PHCs)?

The area has been reporting epidemics. ### Explanation The **Enhanced Malaria Control Project (EMCP)** was launched in 1997 with support from the World Bank to intensify malaria control in high-burden areas. The selection of Primary Health Centres (PHCs) for this program was based on specific epidemiological criteria aimed at targeting endemicity rather than sporadic outbreaks. **Why Option D is the Correct Answer:** Reporting **epidemics** was **NOT** a criterion for selection under EMCP. The program focused on areas with stable, high-intensity transmission (endemicity) rather than unstable areas prone to sudden epidemics. Epidemic-prone areas were managed under different surveillance protocols of the National Anti-Malaria Programme (NAMP). **Analysis of Incorrect Options (Criteria for EMCP):** * **Option A (API > 2):** An Annual Parasite Incidence (API) of more than 2 for the previous three years was a primary criterion, indicating a sustained high burden of disease. * **Option B (Pf % > 30%):** Areas where *Plasmodium falciparum* accounted for more than 30% of total cases were prioritized due to the higher risk of severe malaria and drug resistance. * **Option C (Reporting Deaths):** Any area reporting deaths due to malaria was automatically considered high-risk and included to reduce mortality. * *Note: Additional criteria included areas with a high proportion of tribal populations.* ### High-Yield Clinical Pearls for NEET-PG * **EMCP Timeline:** Launched in 1997; later integrated into the **National Vector Borne Disease Control Programme (NVBDCP)** in 2003-04. * **API Formula:** (Total confirmed cases in a year / Total population under surveillance) × 1000. * **ABER (Annual Blood Examination Rate):** A key indicator of surveillance quality; it should ideally be **>10%**. * **Current Strategy:** India is currently following the **National Framework for Malaria Elimination (2016-2030)**, aiming for a malaria-free India by 2030.

Q: What is the minimum period required for post-exposure chemoprophylaxis for HIV?

4 weeks. **Explanation:** The correct answer is **4 weeks (28 days)**. Post-exposure prophylaxis (PEP) for HIV is a medical emergency aimed at preventing viral replication and systemic dissemination following potential exposure (e.g., needle-stick injury or sexual assault). **Why 4 weeks is correct:** According to the National AIDS Control Organization (NACO) and WHO guidelines, the standard duration for PEP is **28 days**. This timeframe is based on the biological rationale that it takes approximately 4 weeks of continuous antiretroviral therapy to effectively inhibit the virus from establishing a permanent infection in the host's lymphoid tissues after the initial inoculation. **Analysis of Incorrect Options:** * **6 weeks & 8 weeks:** These durations are unnecessarily long. Extending the regimen beyond 28 days does not provide additional protection but significantly increases the risk of drug toxicity and poor patient compliance. * **12 weeks:** This is often the timeframe used for **follow-up antibody testing** to confirm seroconversion status, but it is not the duration for medication intake. **High-Yield Clinical Pearls for NEET-PG:** * **The "Golden Period":** PEP should ideally be started within **2 hours**, and no later than **72 hours** post-exposure. It is not recommended after 72 hours. * **Preferred Regimen (NACO):** A 3-drug regimen is now standard, typically consisting of **Tenofovir (300mg) + Lamivudine (300mg) + Dolutegravir (50mg)** as a once-daily fixed-dose combination. * **Follow-up Schedule:** Testing for HIV antibodies should be done at baseline, 6 weeks, and 3 months (12 weeks) post-exposure.

Q: When planning home care for a client with hepatitis A, which preventive measure should be emphasized to protect the client’s family?

Using good sanitation with dishes and shared bathrooms. **Explanation:** **1. Why Option B is Correct:** Hepatitis A Virus (HAV) is primarily transmitted via the **fecal-oral route**. In a home setting, the virus is shed in the feces of the infected individual. Transmission occurs through contaminated food, water, or fomites (shared objects). Therefore, the cornerstone of prevention is breaking the chain of transmission through **stringent personal hygiene and sanitation**. This includes meticulous handwashing, disinfecting shared bathrooms, and ensuring dishes are thoroughly cleaned to prevent cross-contamination among family members. **2. Why Other Options are Incorrect:** * **Option A:** Complete isolation is unnecessary. Standard enteric precautions are sufficient. Once jaundice appears, the period of peak infectivity has usually passed. * **Option C & D:** These measures are specific to **Hepatitis B, C, and D**, which are transmitted via parenteral (blood-borne) and sexual routes. While general hygiene is good practice, HAV is not typically spread through blood or needle sharing. **3. NEET-PG High-Yield Pearls:** * **Incubation Period:** 15–45 days (Average: 28 days). * **Infectivity:** Maximum during the late incubation period (2 weeks before the onset of jaundice) and decreases rapidly after jaundice appears. * **Diagnosis:** **Anti-HAV IgM** is the gold standard for acute infection; **Anti-HAV IgG** indicates past infection or immunity. * **Prophylaxis:** * **Active:** Inactivated HAV vaccine (2 doses, 6–12 months apart). * **Passive:** Immunoglobulin (0.02 mL/kg) given within 2 weeks of exposure. * **Complication:** HAV never leads to chronic hepatitis or a carrier state, unlike HBV or HCV. It can, however, rarely cause Fulminant Hepatic Failure.

Question 1

All of the following are zoonotic infections, except?

Accepted Answer

HIV

Answer

Plague

Answer

Japanese Encephalitis

Answer

Tuberculosis

Question 2

What is the primary concern of the District TB Control Programme?

Accepted Answer

Finding out resistant cases

Answer

Finding out new cases

Answer

Detecting cases and ensuring treatment

Answer

All of the above

Question 3

Which of the following statements about chickenpox is false?

Accepted Answer

The secondary attack rate is approximately 60%.

Answer

The causative agent is varicella-zoster virus.

Answer

The incubation period is typically 14-16 days.

Answer

The rash typically spares the palms and soles.

Question 4

What is the best step for malaria control in an environment with high temperature?

Accepted Answer

Remove breeding places

Answer

Wear full-sleeve clothing

Answer

Use indoor insecticides

Answer

Provide early treatment

Question 5

What is/are true regarding the management of a rat bite?

Accepted Answer

Rarely need rabies immunoglobulin

Answer

Vaccinate with antirabies vaccine

Answer

Give tetanus toxoid

Answer

Wash with soap and use antiseptic cream

Question 6

Which of the following has the least chance of transmitting HIV infection?

Accepted Answer

Heterosexual intercourse

Answer

Blood transfusion

Answer

Vertical transmission

Answer

IV drug abuse

Question 7

Which of the following is excluded from the National Vector Borne Disease Control Programme (NVBDCP)?

Accepted Answer

Kyasanur Forest Disease (KFD)

Answer

Malaria

Answer

Filariasis

Answer

Kala-azar

Question 8

Under the Enhanced Malaria Control Programme (EMCP) launched in 1997, which of the following was NOT a criterion for the selection of Primary Health Centres (PHCs)?

Accepted Answer

The area has been reporting epidemics

Answer

API greater than 2 for the last 3 years

Answer

Plasmodium falciparum comprising more than 30% of total malaria cases

Answer

The area has been reporting deaths

Question 9

What is the minimum period required for post-exposure chemoprophylaxis for HIV?

Accepted Answer

4 weeks

Answer

6 weeks

Answer

8 weeks

Answer

12 weeks

Question 10

When planning home care for a client with hepatitis A, which preventive measure should be emphasized to protect the client’s family?

Accepted Answer

Using good sanitation with dishes and shared bathrooms

Answer

Keeping the client in complete isolation

Answer

Avoiding contact with blood-soiled clothing or dressings

Answer

Forbidding the sharing of needles or syringes

Infectious Diseases — MCQs

Infectious Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?