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

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 2

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 3

What is the isolation period for Hepatitis A?

Accepted Answer

2 weeks

Answer

1 week

Answer

3 weeks

Answer

4 weeks

Question 4

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 5

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 6

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 7

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 8

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 9

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

Question 10

A contact carrier in cholera has which of the following characteristics?

Accepted Answer

Duration of carrier state is less than 10 days

Answer

Gallbladder is infected

Answer

Stools are not positive for cholera vibrio

Answer

Does not play any role in the spread of infection

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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