Infectious Diseases Practice Questions

Q: Direct disease transmission from person to person is NOT seen in which of the following?

Malaria. ### Explanation The core concept tested here is the **mode of transmission**. Direct transmission involves the immediate transfer of an infectious agent from an infected host to a receptive portal of entry through physical contact (touching, kissing, sexual intercourse) or droplet spray (within 1 meter). **Why Malaria is the Correct Answer:** Malaria is a **vector-borne disease** caused by *Plasmodium* parasites. It requires an intermediate biological vector—the female *Anopheles* mosquito—to complete its life cycle (sporogony) and transmit the infection to another human. It is **not** transmitted through direct person-to-person contact (e.g., you cannot "catch" malaria by sitting next to or touching an infected patient). **Analysis of Incorrect Options:** * **B. Influenza:** Transmitted via **droplet infection** (a form of direct transmission) when an infected person coughs or sneezes, as well as through direct contact with contaminated hands. * **C. Hepatitis:** Hepatitis B and C are transmitted through **direct contact** with infected blood or body fluids (sexual contact, vertical transmission). Hepatitis A and E are transmitted via the feco-oral route. * **D. Impetigo:** A highly contagious bacterial skin infection (usually *Staph. aureus* or *Strep. pyogenes*) transmitted through **direct skin-to-skin contact** or shared items (fomites). **High-Yield NEET-PG Pearls:** * **Direct Transmission types:** Contact (Physical), Droplet spray, Contact with soil, Inoculation into skin/mucosa, and Transplacental (Vertical). * **Indirect Transmission types:** Vector-borne, Vehicle-borne, Air-borne (droplet nuclei/dust), and Fomite-borne. * **Malaria Exception:** While person-to-person transmission is not "direct" in the clinical sense, malaria can rarely be transmitted via blood transfusion or needle sharing (accidental inoculation).

Q: What is the isolation period for Hepatitis A?

2 weeks. **Explanation:** The isolation period for Hepatitis A is **2 weeks**, specifically calculated from the onset of clinical symptoms (jaundice). **Why 2 weeks is correct:** Hepatitis A virus (HAV) is primarily transmitted via the feco-oral route. The period of maximum infectivity occurs during the late incubation period (2 weeks before the onset of jaundice) and continues for about **one week after** the appearance of jaundice. Therefore, isolating the patient for 2 weeks from the onset of symptoms covers the tail end of viral shedding in the feces, effectively preventing the spread of the virus in community or hospital settings. **Analysis of Incorrect Options:** * **A. 1 week:** While viral shedding decreases significantly after 7 days of jaundice, it may still persist in some individuals. One week is considered insufficient for complete safety in public health guidelines. * **C & D. 3 and 4 weeks:** These periods are unnecessarily long. By the end of the second week of jaundice, fecal excretion of the virus typically reaches non-detectable levels, making prolonged isolation clinically redundant. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** 15–45 days (Average: 28 days). * **Secondary Attack Rate (SAR):** High among household contacts. * **Control of Outbreak:** The most effective measure is the administration of the Hepatitis A vaccine. * **Post-exposure Prophylaxis:** Should be given within 2 weeks of exposure (Vaccine is preferred over Immunoglobulin for ages 1–40). * **Diagnosis:** Detection of **IgM anti-HAV** is the gold standard for acute infection.

Q: What is the percentage of people examined showing microfilaria in blood and/or disease manifestation called?

Filaria endemicity rate. ### Explanation **1. Why the Correct Answer is Right:** The **Filaria Endemicity Rate** is a comprehensive epidemiological indicator used to assess the overall burden of lymphatic filariasis in a community. It is calculated as the percentage of people examined who show **either** microfilaria in their blood (infection) **and/or** clinical signs of the disease (manifestation), such as elephantiasis or hydrocele. * **Formula:** (Number of persons with microfilaria + Number of persons with disease / Total persons examined) × 100. **2. Analysis of Incorrect Options:** * **A. Microfilaria Rate:** This refers specifically to the percentage of people whose blood samples are positive for microfilaria (infection only). It does not include those with clinical disease manifestations. * **B. Microfilaria Detection Rate:** This is not a standard epidemiological term in filariasis surveys; it is often confused with the Microfilaria Rate. * **C. Annual Infection Rate:** This measures the probability of a person being infected with filarial larvae over one year, usually calculated based on the density of infective mosquitoes and the biting rate (Entomological Inoculation Rate). **3. High-Yield Clinical Pearls for NEET-PG:** * **Microfilaria Density:** The average number of microfilariae per mm³ of blood in the examined population. * **Night Blood Survey:** Since microfilariae (*W. bancrofti*) exhibit **nocturnal periodicity**, blood collection must be done between **10 PM and 2 AM**. * **Elimination Goal:** The Global Programme to Eliminate Lymphatic Filariasis (GPELF) aims for elimination using **Mass Drug Administration (MDA)** of DEC + Albendazole (and Ivermectin in IDA regimens). * **Target:** Elimination is defined as a Microfilaria rate of **<1%** in the community.

Q: According to WHO, what classification is given to a spleen rate of 11-50%?

Mesoendemic. This question pertains to the **WHO classification of Malaria Endemicity**, which is primarily based on the **Spleen Rate** (the percentage of children aged 2–9 years with a palpable spleen) in a given community. ### **Explanation of the Correct Answer** The correct answer is **Mesoendemic**. According to the WHO criteria, malaria endemicity is categorized as follows: * **Hypoendemic:** Spleen rate in children (2–9 years) is **≤ 10%**. * **Mesoendemic:** Spleen rate in children (2–9 years) is **11–50%**. * **Hyperendemic:** Spleen rate in children (2–9 years) is **constantly > 50%**. In this stage, the adult spleen rate is also high (> 25%). * **Holoendemic:** Spleen rate in children (2–9 years) is **constantly > 75%**. However, the adult spleen rate is low (due to high immunity). Since the question specifies a range of 11–50%, it falls squarely into the **Mesoendemic** category. ### **Why Other Options are Incorrect** * **Holoendemic:** Incorrect because it requires a spleen rate > 75% in children and is characterized by intense transmission where adults develop significant immunity. * **Hyperendemic:** Incorrect because it requires a spleen rate > 50% in children and a high spleen rate in the adult population. ### **NEET-PG High-Yield Pearls** * **Age Group:** Remember that the standard WHO spleen rate is measured in children aged **2 to 9 years**. * **Hackett’s Grading:** While the spleen rate measures the *prevalence* of enlarged spleens, **Hackett’s Grading (0 to 5)** is used to measure the *degree* of splenic enlargement. * **Adult Spleen Rate:** This is a key differentiator between Hyperendemic (High adult spleen rate) and Holoendemic (Low adult spleen rate due to acquired immunity). * **Endemic vs. Epidemic:** Endemicity refers to the constant presence of the disease, whereas an epidemic is a sudden increase above expected levels.

Q: A "safe strategy" has been developed for the control of which of the following conditions?

Trachoma. The **SAFE strategy** is a comprehensive public health approach developed by the World Health Organization (WHO) to eliminate **Trachoma** as a public health problem. Trachoma, caused by *Chlamydia trachomatis* (serotypes A, B, Ba, and C), is the leading infectious cause of blindness worldwide. The acronym **SAFE** stands for: * **S – Surgery:** To treat trichiasis (inward-turning eyelashes) and prevent corneal scarring. * **A – Antibiotics:** Mass Drug Administration (MDA) of **Azithromycin** (single dose) or topical Tetracycline to treat the active infection. * **F – Facial cleanliness:** Encouraging regular face washing to reduce transmission via eye and nose secretions. * **E – Environmental improvement:** Improving access to water and sanitation to reduce fly populations (*Musca sorbens*) and improve hygiene. **Analysis of Incorrect Options:** * **A. Conjunctivitis:** While common, it is usually self-limiting or treated with specific topical agents; there is no standardized global "SAFE" protocol for general conjunctivitis. * **C. Refractive Error:** Managed via the **NPCBVI** (National Programme for Control of Blindness and Visual Impairment) through school screening and provision of spectacles, not the SAFE strategy. * **D. Ocular Trauma:** Managed through emergency clinical intervention and workplace safety regulations, not a community-based public health strategy like SAFE. **High-Yield Clinical Pearls for NEET-PG:** * **WHO GET 2020:** The global initiative to eliminate blinding trachoma. * **Drug of Choice:** Oral Azithromycin (20 mg/kg up to 1g). * **Vector:** The eye-seeking fly, *Musca sorbens*. * **McCallan Classification:** Used to stage Trachoma (Stage I-IV). * **SAFE Strategy Target:** Trachoma is considered eliminated as a public health problem when the prevalence of follicular trachoma (TF) is <5% in children aged 1–9 years.

Question 1

Isolation is strictly recommended for which of the following conditions?

Accepted Answer

Pneumonic plague

Answer

HIV

Answer

Measles

Answer

Brucellosis

Question 2

The Revised National Tuberculosis Control Programme (RNTCP) was started after an evaluation of the previous program by a committee in 1992. How did it differ from the previous program?

Accepted Answer

Strategy for multidrug-resistant TB cases

Answer

Active case finding

Answer

Prophylactic vaccines to newborns

Answer

Unsupervised short course therapy

Question 3

Direct disease transmission from person to person is NOT seen in which of the following?

Accepted Answer

Malaria

Answer

Influenza

Answer

Hepatitis

Answer

Impetigo

Question 4

What is the isolation period for Hepatitis A?

Accepted Answer

2 weeks

Answer

1 week

Answer

3 weeks

Answer

4 weeks

Question 5

What is the percentage of people examined showing microfilaria in blood and/or disease manifestation called?

Accepted Answer

Filaria endemicity rate

Answer

Microfilaria rate

Answer

Microfilaria detection rate

Answer

Annual infection rate

Question 6

According to WHO, what classification is given to a spleen rate of 11-50%?

Accepted Answer

Mesoendemic

Answer

Holoendemic

Answer

Hyperendemic

Answer

None of the above

Question 7

All of the following cause a false positive Mantoux test except?

Accepted Answer

HIV/AIDS

Answer

Prior BCG vaccine

Answer

Degraded tuberculin

Answer

Faulty technique of injection

Question 8

Which of the following activities is not evaluated to determine the extent of goal achievement in a dracunculiasis elimination program?

Accepted Answer

Registration of new cases

Answer

Provision of protected water sources

Answer

Health education

Answer

Chemical disinfection of water sources

Question 9

According to RNTCP, tubercular pericarditis should be treated with which category of anti-tubercular regimen?

Accepted Answer

Category I

Answer

Category III

Answer

Category II

Answer

Category IV

Question 10

A "safe strategy" has been developed for the control of which of the following conditions?

Accepted Answer

Trachoma

Answer

Conjunctivitis

Answer

Refractive error

Answer

Ocular trauma

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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