Infectious Diseases Practice Questions

Q: Which of the following diseases are transmitted by Aedes aegypti?

Dengue. **Explanation** The correct answer is **Dengue**. *Aedes aegypti*, also known as the "tiger mosquito" due to its striped appearance, is the primary vector for Dengue fever. It is a day-biting mosquito that typically breeds in artificial collections of clean water (e.g., flower pots, discarded tires, coolers). **Analysis of Options:** * **Dengue (Correct):** Transmitted by *Aedes aegypti* and *Aedes albopictus*. It is characterized by high fever, retro-orbital pain, and "break-bone" joint pain. * **Japanese Encephalitis (Incorrect):** Transmitted primarily by **Culex** mosquitoes (specifically *Culex tritaeniorhynchus*), which breed in rice fields and stagnant water. * **Kyasanur Forest Disease (Incorrect):** This is a viral hemorrhagic fever transmitted by **Hard Ticks** (*Haemaphysalis spinigera*). It is endemic to the Western Ghats of India. * **Yellow Fever (Incorrect):** While *Aedes aegypti* **is** the vector for Yellow Fever, in the context of Indian competitive exams like NEET-PG, Dengue is the classic association because Yellow Fever is not endemic to India. (Note: If the question allows multiple correct answers, both C and D would be technically correct, but Dengue is the most clinically relevant answer in the Indian subcontinent). **High-Yield NEET-PG Pearls:** * **Aedes aegypti** also transmits: Chikungunya, Zika virus, and Rift Valley Fever. * **Bionomics:** It is a "nervous feeder" (bites multiple people to complete one meal) and has a flight range of approximately 100 meters. * **Control:** The most effective control measure is **Source Reduction** (eliminating breeding sites). The "Aedes Index" (House Index) is used to monitor the risk of outbreaks.

Q: Aedes mosquito transmits all the following diseases, EXCEPT?

West Nile fever. **Explanation:** The correct answer is **West Nile fever** because it is primarily transmitted by the **Culex** mosquito (specifically *Culex pipiens* complex), not the Aedes mosquito. ### 1. Why West Nile Fever is the Exception: West Nile Virus (WNV) is a flavivirus maintained in an **enzootic cycle** between birds (natural reservoir) and Culex mosquitoes. Humans and horses are "dead-end hosts." While Aedes species can occasionally carry the virus, they are not the primary vectors responsible for human outbreaks. ### 2. Analysis of Incorrect Options (Diseases transmitted by Aedes): * **Dengue:** Transmitted primarily by *Aedes aegypti* (principal vector) and *Aedes albopictus*. * **Chikungunya:** Caused by a Togavirus, transmitted by the same Aedes species as Dengue. * **Yellow Fever:** Transmitted by *Aedes aegypti* in urban cycles and *Haemagogus* species in jungle cycles. ### 3. High-Yield Clinical Pearls for NEET-PG: * **Aedes aegypti Characteristics:** Known as the "Tiger Mosquito" due to white stripes on its body. It is a **day-biter** (mostly early morning and late afternoon), breeds in **artificial collections of clean water** (coolers, tires, flower pots), and is a "nervous feeder" (bites multiple people to complete one meal). * **Vector for Zika:** Aedes mosquitoes also transmit the Zika virus. * **Culex vs. Aedes:** Remember the mnemonic: **C**ulex for **C**ulex-borne diseases like Japanese Encephalitis, West Nile, and Bancroftian Filariasis. * **Flight Range:** Aedes has a short flight range (usually <100 meters), making localized vector control highly effective.

Q: A 2-year duration in terms of leprosy refers to what?

Post-treatment surveillance of paucibacillary leprosy. ### Explanation In the context of the National Leprosy Eradication Programme (NLEP), the duration of **post-treatment surveillance** (follow-up) is a critical component to monitor for relapse or late reactions. **1. Why Option C is Correct:** According to NLEP guidelines, once a patient completes the Multi-Drug Therapy (MDT) regimen, they enter a surveillance phase. For **Paucibacillary (PB) leprosy**, the surveillance period is **2 years**. During this time, patients are monitored to ensure there is no clinical recurrence of the disease. **2. Analysis of Incorrect Options:** * **Option A:** The treatment duration for PB leprosy is **6 months** (to be completed within a maximum of 9 months). * **Option B:** The treatment duration for Multibacillary (MB) leprosy is **12 months** (to be completed within a maximum of 18 months). * **Option D:** The post-treatment surveillance period for **MB leprosy** is **5 years**, reflecting the higher bacterial load and increased risk of late relapse compared to PB cases. **3. High-Yield Clinical Pearls for NEET-PG:** * **Classification:** PB leprosy involves 1–5 lesions and no nerve involvement (or only one nerve); MB leprosy involves >5 lesions or ≥2 nerve involvements. * **MDT Regimen (Adult MB):** Rifampicin (600mg monthly), Dapsone (100mg daily), and Clofazimine (300mg monthly + 50mg daily). * **MDT Regimen (Adult PB):** Rifampicin (600mg monthly) and Dapsone (100mg daily). * **Accompanied MDT:** A strategy where the full course of MDT is provided to the patient at the start to ensure treatment completion in difficult-to-reach areas. * **Release from Treatment (RFT):** A patient is "released from treatment" after completing the pulses, regardless of the persistence of skin patches, as these often take time to fade.

Q: All of the following diseases are transmitted by mosquito vectors except?

Babesiosis. **Explanation:** The correct answer is **Babesiosis** because it is a tick-borne zoonosis, not a mosquito-borne disease. **1. Why Babesiosis is the correct answer:** Babesiosis is caused by intraerythrocytic protozoa of the genus *Babesia*. It is primarily transmitted by the bite of **Ixodes ticks** (hard ticks), the same vector responsible for Lyme disease. It is clinically significant as it can mimic malaria due to the destruction of red blood cells, leading to hemolytic anemia and jaundice. **2. Analysis of Incorrect Options (Mosquito-borne diseases):** * **West Nile Fever:** Transmitted by the **Culex** mosquito. It is a viral zoonosis that can lead to fatal neurological diseases in humans. * **Brugian Filariasis:** Caused by *Brugia malayi* or *B. timori*. The primary vectors are mosquitoes of the **Mansonia** and **Anopheles** genera. * **Rift Valley Fever (RVF):** A viral zoonosis primarily transmitted by **Aedes** and **Culex** mosquitoes. Outbreaks are often associated with heavy rainfall and flooding. **High-Yield Clinical Pearls for NEET-PG:** * **Vector Identification:** Always remember the "Big Three" for Ixodes ticks: **Lyme disease, Babesiosis, and Human Granulocytic Anaplasmosis.** * **Maltese Cross Appearance:** On a peripheral blood smear, *Babesia* parasites often form a tetrad structure known as a "Maltese Cross," which is pathognomonic and distinguishes it from *Plasmodium falciparum*. * **Mansonia Mosquito:** Specifically associated with **Brugian Filariasis** and is unique because its larvae attach to the roots of aquatic plants (e.g., *Pistia*) for respiration.

Q: The "EYE" strategy is developed for the elimination of which disease?

Yellow fever. **Explanation:** The **EYE strategy** stands for **"Eliminate Yellow Fever Epidemics."** It is a comprehensive global strategy launched in 2017 by the WHO, UNICEF, and Gavi, the Vaccine Alliance. The initiative was developed in response to the resurgence of Yellow Fever and aims to protect nearly 1 billion people in 40 high-risk countries (mainly in Africa and the Americas) by 2026. **The strategy relies on three strategic pillars:** 1. Protecting at-risk populations through vaccination. 2. Preventing international spread. 3. Containing outbreaks rapidly. **Analysis of Incorrect Options:** * **A. Yaws:** The global strategy for Yaws is the **"Morges Strategy,"** which focuses on eradication using oral Azithromycin. * **C. Leptospirosis:** There is no specific "EYE" strategy for Leptospirosis; control focuses on rodent control and sanitation. * **D. Zika virus:** While Zika is a flavivirus like Yellow Fever, its control falls under the **"Zika Strategic Response Framework,"** focusing on vector control and pregnancy monitoring. **High-Yield NEET-PG Pearls:** * **Yellow Fever Vaccine:** The **17D strain** is a live-attenuated vaccine. It provides lifelong immunity (as per WHO International Health Regulations since 2016). * **Validity:** The International Certificate of Vaccination becomes valid **10 days** after vaccination. * **Vector:** Primarily *Aedes aegypti* (Urban cycle) and *Haemagogus* species (Sylvan/Jungle cycle). * **India Status:** India is "Yellow Fever free" but remains receptive due to the presence of the *Aedes* vector. Strict quarantine rules apply to travelers from endemic zones.

Q: What is the standard first-line treatment regimen for Category 1 tuberculosis?

HRZE (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol). **Explanation:** Under the National Tuberculosis Elimination Program (NTEP), the standard treatment for all new cases of tuberculosis (formerly known as Category 1) follows a standardized short-course chemotherapy regimen. **1. Why Option A is Correct:** The standard regimen consists of an **Intensive Phase (IP)** of 2 months and a **Continuation Phase (CP)** of 4 months. * **Intensive Phase:** Uses four drugs—**H** (Isoniazid), **R** (Rifampicin), **Z** (Pyrazinamide), and **E** (Ethambutol)—to rapidly kill the actively multiplying bacilli and prevent the emergence of drug resistance. * **Continuation Phase:** Uses three drugs (**HRE**) for 4 months to eliminate semi-dormant bacilli and prevent relapse. (Note: In the current daily regimen, Ethambutol is included in the CP). **2. Analysis of Incorrect Options:** * **Option B (HRE):** This lacks Pyrazinamide. Pyrazinamide is essential in the first 2 months due to its unique ability to kill intracellular bacilli in acidic environments. * **Option C (ZRE):** This lacks Isoniazid (H), which is the most potent bactericidal drug against rapidly dividing organisms. * **Option D (HRZES):** This was the old "Category 2" regimen for previously treated cases. Streptomycin (S) is no longer used in standard first-line therapy to reduce the risk of ototoxicity and because the "Category 2" classification has been phased out in favor of drug-susceptibility testing (DST). **High-Yield Clinical Pearls for NEET-PG:** * **Dosage:** NTEP uses **daily fixed-dose combinations (FDC)** based on weight bands. * **Drug of Choice for Prophylaxis:** Isoniazid (6 months). * **Pyridoxine (Vit B6):** Always co-administer with Isoniazid to prevent peripheral neuropathy. * **Monitoring:** Sputum microscopy is done at the end of the IP (2 months) to assess conversion. * **Rifampicin:** The most important component; it causes orange-colored urine (benign side effect).

Q: How can the rash of chickenpox be differentiated from the rash of smallpox?

Deep seated. The differentiation between Chickenpox (Varicella) and Smallpox (Variola) is a classic high-yield topic in Community Medicine. The key lies in the depth and evolution of the skin lesions. **Explanation of the Correct Answer:** * **Deep-seated (C):** Smallpox rashes are characteristically **deep-seated and firm** (often described as "shotty" to the touch) because the virus affects the deeper layers of the dermis. In contrast, Chickenpox rashes are **superficial** and thin-walled, often described as "dewdrops on a rose petal." **Analysis of Incorrect Options:** * **Pleomorphic (A):** This is a hallmark of **Chickenpox**, not Smallpox. Pleomorphism means that all stages of the rash (papules, vesicles, and crusts) are visible simultaneously in the same area. In Smallpox, the rash is "monomorphic" (all lesions in one area are at the same stage of development). * **Centripetal (B):** This describes the distribution of **Chickenpox**, where the rash is most dense on the trunk and sparse on the extremities (it "flees the center"). Smallpox is **Centrifugal**, meaning it is most dense on the face and distal limbs (palms and soles are involved). * **Unilocular (D):** Smallpox vesicles are typically **multilocular** and umbilicated (having a central depression). If pricked, they do not collapse entirely. Chickenpox vesicles are **unilocular**; if pricked, the entire fluid escapes, and the vesicle collapses. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Smallpox (12 days) vs. Chickenpox (14–16 days). * **Fever:** In Smallpox, fever subsides with the onset of rash; in Chickenpox, fever rises with each fresh crop of rash. * **Axilla:** Smallpox typically spares the axilla, whereas Chickenpox often involves it. * **Eradication:** Smallpox was declared eradicated by the WHO on **May 8, 1980**.

Question 1

Which of the following diseases are transmitted by Aedes aegypti?

Accepted Answer

Dengue

Answer

Japanese Encephalitis

Answer

Kyasanur Forest Disease

Answer

Yellow Fever

Question 2

A sexually active woman presents with vaginal discharge. According to the syndromic approach for management, which of the following drug regimens should be prescribed?

Accepted Answer

Metronidazole, Azithromycin, Fluconazole

Answer

Metronidazole

Answer

Azithromycin

Answer

Metronidazole and Fluconazole

Question 3

In Salmonellosis disease, until when is isolation recommended?

Accepted Answer

Until stool culture is negative for three consecutive times

Answer

Until fever subsides

Answer

Until blood culture is negative

Answer

Until spleen size returns to normal

Question 4

Aedes mosquito transmits all the following diseases, EXCEPT?

Accepted Answer

West Nile fever

Answer

Dengue

Answer

Chikungunya

Answer

Yellow fever

Question 5

Which of the following statements regarding leprosy is false?

Accepted Answer

A defaulter is defined as a patient who has not collected treatment for 6 months.

Answer

Multibacillary leprosy is defined as a patient having more than 5 skin lesions.

Answer

The target for elimination of leprosy is a prevalence rate below 1 per 10,000 population.

Answer

Annual New Case Detection Rate (ANCDR) is a measure of the incidence of leprosy.

Question 6

A 2-year duration in terms of leprosy refers to what?

Accepted Answer

Post-treatment surveillance of paucibacillary leprosy

Answer

Treatment of paucibacillary leprosy

Answer

Treatment of multibacillary leprosy

Answer

Post-treatment surveillance of multibacillary leprosy

Question 7

All of the following diseases are transmitted by mosquito vectors except?

Accepted Answer

Babesiosis

Answer

West Nile fever

Answer

Brugian filariasis

Answer

Rift Valley fever

Question 8

The "EYE" strategy is developed for the elimination of which disease?

Accepted Answer

Yellow fever

Answer

Yaws

Answer

Leptospirosis

Answer

Zika virus

Question 9

What is the standard first-line treatment regimen for Category 1 tuberculosis?

Accepted Answer

HRZE (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol)

Answer

HRE (Rifampicin, Isoniazid, Ethambutol)

Answer

ZRE (Pyrazinamide, Rifampicin, Ethambutol)

Answer

HRZES (Rifampicin, Isoniazid, Pyrazinamide, Ethambutol, Streptomycin)

Question 10

How can the rash of chickenpox be differentiated from the rash of smallpox?

Accepted Answer

Deep seated

Answer

Pleomorphic

Answer

Centripetal

Answer

Unilocular

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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