Infectious Diseases Practice Questions

Q: Which of the following are considered risk factors for tuberculosis?

All of the above. **Explanation:** The correct answer is **D. All of the above.** The underlying medical concept is **Immunosuppression.** Tuberculosis (TB) is an opportunistic infection; any condition that impairs the body’s cell-mediated immunity (specifically T-cell function) increases the risk of progressing from latent TB infection to active disease. * **HIV (Option A):** This is the most potent risk factor for TB. HIV depletes CD4+ T-lymphocytes, which are essential for forming granulomas to contain *Mycobacterium tuberculosis*. An HIV-positive individual has a 20–30 times higher risk of developing active TB compared to someone HIV-negative. * **Type 1 Diabetes Mellitus (Option B):** Hyperglycemia impairs chemotaxis, phagocytosis, and the bactericidal activity of macrophages and neutrophils. Both Type 1 and Type 2 DM are significant risk factors, increasing the risk of TB by approximately 3-fold. * **Chronic Renal Failure (Option C):** Patients with CRF or those on hemodialysis have impaired cellular immunity and uremia-induced immune dysfunction, making them highly susceptible to reactivation of latent TB. **Clinical Pearls for NEET-PG:** * **Most common opportunistic infection in HIV:** Tuberculosis (in India). * **Other high-yield risk factors:** Silicosis (increases risk by 30x), prolonged corticosteroid use, malnutrition (low BMI), and TNF-alpha inhibitors. * **Social factors:** Overcrowding, poor ventilation, and low socioeconomic status are key environmental determinants. * **Screening:** In high-risk groups (like HIV), the Tuberculin Skin Test (TST) is considered positive at an induration of **≥5 mm**.

Q: According to the modified plan of operation, endemic areas were classified based on what parameter?

Annual Parasite Index (API). ### Explanation The **Modified Plan of Operation (MPO)** was launched in **1977** under the National Malaria Eradication Programme (NMEP) to tackle the rising incidence of malaria and the emergence of insecticide resistance. **1. Why API is the Correct Answer:** The Annual Parasite Index (API) is the most critical indicator used to measure the incidence of malaria in a community. Under the MPO, areas were classified based on their API to determine the strategy for intervention: * **API > 2:** High-risk areas requiring intensive **Indoor Residual Spraying (IRS)** with insecticides. * **API 10%), not the endemicity of the disease. * **C. Slide Positivity Rate (SPR):** While it indicates the prevalence of malaria among symptomatic patients, it was not the primary metric for classification under MPO. * **D. Slide Falciparum Rate (SFR):** This measures the proportion of *P. falciparum* cases, used to monitor the severity and risk of cerebral malaria, but not for general area classification. **Clinical Pearls for NEET-PG:** * **MPO Goal:** To prevent deaths and reduce morbidity; it shifted the focus from "eradication" to "effective control." * **API vs. ABER:** Remember, **API** measures the **disease burden**, while **ABER** measures the **program's performance**. * **Current Strategy:** India currently follows the National Framework for Malaria Elimination (2016–2030), categorizing states into Category 0 (Elimination) to Category 3 (High Burden) based on API.

Q: Which of the following should be injected in and around the wound in a class III rabies bite?

Anti-rabies serum. **Explanation:** The management of a Category III rabies bite (single or multiple transdermal bites, scratches, or contamination of mucous membranes with saliva) requires immediate local wound treatment, active immunization (vaccine), and passive immunization. **1. Why Anti-rabies Serum (RIG) is correct:** The primary goal in Category III bites is to neutralize the virus at the site of entry before it can invade the peripheral nerves. **Rabies Immunoglobulin (RIG)** or Anti-rabies serum provides immediate, pre-formed antibodies. According to WHO and National guidelines, as much of the calculated dose of RIG as anatomically feasible must be **infiltrated in and around the wound(s)**. This creates a "protective barrier" of antibodies at the exact site of viral inoculation. **2. Why other options are incorrect:** * **Tetanus toxoid:** While tetanus prophylaxis is part of wound management, it is administered intramuscularly (usually in the deltoid), not infiltrated into the bite wound. * **Antibiotic solution:** Routine infiltration of antibiotics into a bite wound is not recommended. Systemic antibiotics may be prescribed orally if the wound appears infected or is deep, but they do not prevent rabies. **Clinical Pearls for NEET-PG:** * **Dosage:** Human RIG (HRIG) is 20 IU/kg; Equine RIG (ERIG) is 40 IU/kg. * **Site:** If any serum remains after infiltration, it should be injected IM at a site distant from the vaccine injection site. * **Timing:** RIG should be administered as soon as possible (Day 0). It is not recommended beyond 7 days after the first dose of the vaccine, as the body begins producing its own antibodies by then. * **Wound Suturing:** Should be avoided. If necessary, it must be done only after infiltrating RIG and delayed by a few hours.

Q: Measles is infective for how many days before the onset of rash?

4 days. ### Explanation **Correct Option: B (4 days)** The period of communicability for Measles (Rubeola) is defined as **4 days before to 5 days after** the appearance of the rash. This period coincides with the peak of viral shedding from the respiratory tract. The infectivity is highest during the **prodromal stage** (pre-eruptive phase), characterized by the "3 Cs" (Cough, Coryza, Conjunctivitis) and Koplik spots, even before the characteristic maculopapular rash appears. **Analysis of Incorrect Options:** * **Option A (10 days):** This is too long. While the incubation period of Measles is approximately 10–14 days, the patient is not infectious during the early incubation phase. * **Option C (1 day):** This underestimates the window of transmission. Viral shedding begins significantly earlier than 24 hours before the rash. * **Option D (Same day):** This is clinically dangerous to assume. Measles is most contagious *before* the rash appears; by the time the rash is visible, the patient has already been infectious for several days. **High-Yield Clinical Pearls for NEET-PG:** * **Secondary Attack Rate (SAR):** Measles has one of the highest SARs (>90%) among susceptible household contacts. * **Koplik Spots:** These are pathognomonic and appear 1–2 days before the rash on the buccal mucosa opposite the lower second molars. * **Isolation:** A child with measles should be isolated for at least 4 days after the rash appears to prevent transmission. * **Vaccination:** The Measles vaccine is a live attenuated vaccine (Edmonston-Zagreb strain in India) usually given at 9 months and 16–24 months. * **Vitamin A:** Supplementation is recommended for all children with acute measles to prevent complications like blindness and pneumonia.

Q: Which of the following statements is true about COVID-19?

It is a new strain which originated in Wuhan, China.. **Explanation:** **Correct Answer: C. It is a new strain which originated in Wuhan, China.** COVID-19 is caused by the **SARS-CoV-2** virus, a novel strain of the Coronaviridae family that had not been previously identified in humans. The initial outbreak was epidemiologically linked to the Huanan Seafood Wholesale Market in **Wuhan, Hubei Province, China**, in December 2019. It is a zoonotic pathogen that likely jumped from animals to humans. **Analysis of Incorrect Options:** * **Option A:** COVID-19 is caused by a **Coronavirus** (enveloped, positive-sense RNA virus), not an Influenza virus (Orthomyxoviridae). While both cause respiratory illness, they belong to entirely different viral families. * **Option B:** The flu vaccine protects against specific strains of the Influenza virus. There is **no cross-immunity** between the influenza vaccine and SARS-CoV-2. * **Option D:** A significant proportion of COVID-19 cases (estimated 20-40%) are **asymptomatic** or presymptomatic, yet these individuals can still transmit the virus to others. **High-Yield Clinical Pearls for NEET-PG:** * **Receptor:** SARS-CoV-2 binds to the **ACE-2 (Angiotensin-Converting Enzyme 2)** receptors, primarily found in Type II pneumocytes. * **Incubation Period:** Average 5–6 days (Range: 1–14 days). * **Gold Standard Test:** Real-time Reverse Transcription Polymerase Chain Reaction (**RT-PCR**). * **Infectivity Period:** Maximum viral shedding occurs in the early stages of the illness (2 days before to 5 days after symptom onset). * **Cytokine Storm:** Severe cases are characterized by an overproduction of pro-inflammatory cytokines (IL-6, TNF-alpha).

Question 1

A 30-year-old female has sputum-positive tuberculosis. Her child is 3 years old. What is the recommended chemoprophylaxis for the child?

Accepted Answer

Isoniazid 5 mg/kg for 6 months

Answer

Isoniazid 3 mg/kg for 3 months

Answer

Isoniazid 5 mg/kg for 3 months

Answer

Isoniazid 3 mg/kg for 6 months

Question 2

Which of the following are considered risk factors for tuberculosis?

Accepted Answer

All of the above

Answer

HIV

Answer

Type 1 diabetes mellitus

Answer

Chronic renal failure

Question 3

Regarding Schick's test, which of the following is false?

Accepted Answer

A positive test means that the person is immune to Diphtheria.

Answer

An erythematous reaction in both arms indicates hypersensitivity.

Answer

Diphtheria toxin is given intradermally.

Answer

The test is done to find out the immune status against diphtheria.

Question 4

A patient has been recently put on the DOTS Plus regimen. Which of the following drug combinations is included in the treatment of this patient?

Accepted Answer

6 months of Kanamycin, Ofloxacin, Ethionamide, Cycloserine, Pyrazinamide, Ethambutol + 18 months of Ofloxacin, Ethionamide, Cycloserine, Ethambutol

Answer

2 months of Isoniazid, Rifampicin, Ethambutol + 4 months of Isoniazid, Rifampicin

Answer

2 months of Isoniazid, Rifampicin, Pyrazinamide, Ethambutol, Streptomycin + 6 months of Isoniazid, Rifampicin, Ethambutol

Answer

6 months of Isoniazid, Rifampicin, Kanamycin, Ofloxacin + 18 months of Ofloxacin, Kanamycin

Question 5

According to the modified plan of operation, endemic areas were classified based on what parameter?

Accepted Answer

Annual Parasite Index (API)

Answer

Age-Breakdown of Residuals (ABER)

Answer

Slide positivity rate

Answer

Slide falciparum rate

Question 6

Which of the following should be injected in and around the wound in a class III rabies bite?

Accepted Answer

Anti-rabies serum

Answer

Tetanus toxoid

Answer

Antibiotic solution

Answer

None of the above

Question 7

Measles is infective for how many days before the onset of rash?

Accepted Answer

4 days

Answer

10 days

Answer

1 day

Answer

On the same day

Question 8

Which of the following strategies is NOT included in preventing HIV transmission?

Accepted Answer

Antiretroviral treatment

Answer

Education

Answer

Treatment of sexually transmitted diseases

Answer

Condoms

Question 9

Which of the following statements is true about COVID-19?

Accepted Answer

It is a new strain which originated in Wuhan, China.

Answer

COVID-19 is a type of influenza virus.

Answer

Those who take flu vaccine are immune to COVID-19.

Answer

All cases of COVID-19 are symptomatic.

Question 10

Which of the following is not true about the National AIDS Control Programme?

Accepted Answer

Community-based screening for the prevalence of HIV has been taken up.

Answer

Sentinel surveillance methodology has been adopted.

Answer

Early diagnosis and treatment of STD is one of the major strategies to control the spread of HIV.

Answer

Guidelines for blood banks, blood donors, and dialysis units are formulated.

Infectious Diseases — MCQs

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