Infectious Diseases Practice Questions

Q: True about Mantoux is -

False negative in fulminant diseases. ***False negative in fulminant diseases*** - In **fulminant diseases** such as **miliary tuberculosis** or severe **immunosuppression**, the body's immune response may be too weak to mount a detectable reaction to the tuberculin, leading to a **false negative result**. - This occurs because the cell-mediated immunity, which is responsible for the Mantoux reaction, is compromised. *If once done, next time it is always positive* - This is incorrect as a positive Mantoux test indicates **prior exposure** to *Mycobacterium tuberculosis* or **BCG vaccination**, but the immune response can wane over time or be affected by immunosuppression. - Subsequent tests can be negative if the immune memory fades or if the individual's immune system is compromised. *Results are given in terms of positive & negative* - The results are interpreted based on the **diameter of induration** (hardening) measured in millimeters, not simply as positive or negative. - The threshold for a positive result varies depending on the individual's risk factors and clinical context. *Indurations given in terms of length & breadth* - The **induration** (palpable raised area) is measured across its **diameter** in millimeters at its widest point, not in terms of separate length and breadth measurements. - Only the induration is measured, not any surrounding erythema (redness).

Q: A 40-year-old man underwent kidney transplantation. Two months after transplantation, he developed fever and features suggestive of bilateral diffuse interstitial pneumonia. Which of the following is the most likely etiologic agent?

Cytomegalovirus. ***Cytomegalovirus*** - **CMV infection** is very common and a frequent opportunistic infection in **immunosuppressed solid organ transplant recipients**, especially within the first few months post-transplant [1]. - **CMV pneumonitis**, characterized by diffuse interstitial pneumonia and fever, is a classic presentation of CMV disease in this patient population [1]. *Varicella zoster virus* - While VZV can cause serious infections in immunosuppressed individuals, **pneumonia due to VZV** is typically part of a disseminated disease and less common than CMV pneumonitis in transplant recipients. - **Cutaneous vesicular lesions** would usually precede or accompany VZV pneumonia, which are not mentioned here. *Herpes simplex virus* - HSV can cause severe mucocutaneous infections in immunocompromised patients, but **HSV pneumonia** is rare and usually manifests as tracheobronchitis or a focal necrotizing pneumonia, not typically diffuse interstitial. - **Esophagitis or encephalitis** are more common serious manifestations of HSV in this population than primary pneumonitis. *Epstein-barr virus* - EBV is primarily associated with **post-transplant lymphoproliferative disorder (PTLD)** in transplant recipients, which can involve the lungs. - While PTLD can manifest with fever and pulmonary infiltrates, **diffuse interstitial pneumonia** solely due to primary EBV infection is less characteristic than for CMV.

Q: The CSF findings in TB meningitis include –

Low sugar + high protein and Lymphocytosis. ***Low sugar + high protein and Lymphocytosis*** - **Tuberculous meningitis** typically presents with **low CSF glucose** because the infecting *Mycobacterium tuberculosis* consumes glucose [2]. - There is a characteristic **high CSF protein** due to inflammation and increased permeability of the blood-brain barrier [2], along with a **lymphocytic pleocytosis** as the immune response is often T-cell mediated [1]. *High sugar + high chloride* - This combination is not characteristic of **Tuberculous meningitis** or any common form of meningitis. - **CSF glucose** is typically low in bacterial and tuberculous meningitis due to consumption by microbes [2]. *High sugar + low protein* - **High CSF glucose** and **low protein** are not consistent with **Tuberculous meningitis** or other forms of meningitis. - In meningitis, inflammation generally leads to elevated protein levels [2]. *Low sugar + high protein and Lymphopenia* - While **low sugar** and **high protein** are typical in **Tuberculous meningitis**, **lymphopenia** (low lymphocyte count) is incorrect. - The inflammatory response in **Tuberculous meningitis** is primarily characterized by a **lymphocytic pleocytosis**, meaning an increase in lymphocytes [1].

Q: Pneumococcal meningitis is associated with the following CSF findings:

Pleocytosis with high protein and low sugar. ***Pleocytosis with high protein and low sugar*** - **Bacterial meningitis**, such as that caused by pneumococcus, typically presents with **neutrophilic pleocytosis** (increased white blood cells, predominantly neutrophils) due to the inflammatory response. - The high bacterial load and increased protein leakage from inflamed meninges lead to **elevated CSF protein**, while bacterial consumption of glucose results in **low CSF glucose** [1]. *Pleocytosis with low protein and low sugar* - While **pleocytosis** and **low sugar** (hypoglycorrhachia) are characteristic of bacterial meningitis, **low protein** is not. - Bacterial infections typically cause increased protein in the CSF due to inflammation and breakdown of the blood-brain barrier [1]. *Lymphocytosis with low protein and low sugar* - **Lymphocytosis** is usually seen in **viral or fungal meningitis**, not bacterial meningitis, where neutrophils predominate [1]. - **Low protein** is inconsistent with bacterial meningitis, which typically causes **high protein** in the CSF. *Lymphocytosis with high protein and low sugar* - This combination is partially inconsistent; while **high protein** and **low sugar** can be seen in some severe or chronic forms of meningitis, **lymphocytosis** is not the primary cell response in **acute bacterial meningitis**. [1] - **Lymphocytosis** would typically suggest a viral, fungal, or tuberculous etiology.

Q: Which of the following statements is true about dengue fever? a) ↑ Hematocrit b) ↓ Platelet c) Positive tourniquet test d) Vector (Aedes aegypti) usually bites in day time

Vector (Aedes aegypti) usually bites in day time. ***Vector (Aedes aegypti) usually bites in day time*** - The **Aedes aegypti mosquito**, the primary vector for dengue, is a **day-biting** mosquito, particularly active during early morning and late afternoon. - This characteristic behavior influences prevention strategies, as protection is needed during daylight hours. *↑ Hematocrit* - An **increased hematocrit** is a sign of **plasma leakage** and **hemoconcentration**, which is a *potential complication* of severe dengue [1]. - While it can occur, it's not a universal feature of all dengue cases and is more indicative of **dengue hemorrhagic fever** or **dengue shock syndrome** [1]. *↓ Platelet* - A **decrease in platelet count (thrombocytopenia)** is a common finding in dengue fever, often indicative of viral suppression of bone marrow or increased platelet destruction. - However, the severity of thrombocytopenia can vary, and it's not the *most universally true* or defining characteristic compared to the vector's biting habits. *Positive tourniquet test* - A **positive tourniquet test** (petechiae appearing after pressure application) is an indicator of **capillary fragility** and a sign of possible dengue, especially in endemic areas [1]. - While frequently observed in dengue, particularly in **dengue hemorrhagic fever**, it is not always positive and its absence doesn't rule out the infection [1].

Q: Kissing disease is also known as

Glandular fever. ***Glandular fever*** - **Glandular fever** is the common name for **infectious mononucleosis**, which is frequently nicknamed the "kissing disease" due to its primary transmission route through saliva [1]. - It is predominantly caused by the **Epstein-Barr virus (EBV)** [1]. *Rubella* - Rubella is commonly known as **German measles** and is also a viral infection, but it presents with a characteristic rash and is not associated with the term "kissing disease." - It can cause serious complications like **congenital rubella syndrome** if contracted during pregnancy. *Scarlet fever* - Scarlet fever is a bacterial infection caused by **Streptococcus pyogenes** (Group A Strep) and is characterized by a distinctive red rash and sore throat. - It is not referred to as the "kissing disease" and is primarily spread through respiratory droplets. *Acute herpetic gingivostomatitis* - This condition is caused by the **Herpes Simplex Virus (HSV-1)** and primarily involves inflammation and sores in the mouth and gums [2]. - While it can be transmitted via saliva, it is not commonly known as the "kissing disease" and its clinical presentation is distinct from glandular fever [2].

Q: Which of the following statements regarding classical Dengue fever is FALSE?

Positive tourniquet test. **CRITICAL ISSUE:** This question as currently written is problematic because **all four statements are TRUE** about classical dengue fever, making it impossible to identify a FALSE statement. ***Analysis of Each Statement:*** **Positive tourniquet test** (Currently marked as answer) - This is actually a **TRUE statement** about classical dengue fever - The tourniquet test is **positive in classical dengue fever** and is used as a diagnostic criterion by WHO - A positive tourniquet test indicates capillary fragility and is seen in both classical dengue and DHF - **This should NOT be the answer** to a FALSE question **Low case fatality rate** - TRUE statement: Classical dengue fever has a very low case fatality rate (<1%) with proper supportive care - Mortality is primarily associated with severe dengue/DHF/DSS **Self limiting disease** - TRUE statement: Classical dengue is typically self-limiting, resolving within 7-10 days with symptomatic treatment - Characterized by fever, headache, retro-orbital pain, myalgia, and rash **Transmitted by Aedes aegypti** - TRUE statement: **Aedes aegypti** is the primary vector for dengue transmission - Also transmitted by Aedes albopictus in some regions - Day-biting mosquitoes found in urban/semi-urban areas **RECOMMENDATION:** This question needs revision as it currently has no correct answer. All options are true statements about classical dengue fever.

Q: Sero conversion in HIV Infection takes place in ?

4 weeks. ***4 weeks*** - HIV **seroconversion**, the time when antibodies to HIV become detectable, typically occurs around **3 to 6 weeks** (approximately 4 weeks on average) after initial infection. - During this period, individuals may experience **acute retroviral syndrome**, which presents with flu-like symptoms. *12 weeks* - While 12 weeks (3 months) was historically considered the upper end of the window period for HIV antibody testing, **newer, more sensitive tests** can detect seroconversion much earlier [1]. - Waiting 12 weeks is more relevant for older generation antibody tests, not current standard tests. *9 weeks* - This falls within the broader range of the window period, but it's not the average or most common time for seroconversion with modern testing. - Many individuals will have already seroconverted by 9 weeks, especially with **third and fourth-generation tests** [1]. *2 weeks* - This is generally too early for HIV **antibody seroconversion** to reliably occur. - While some highly sensitive tests (e.g., p24 antigen or nucleic acid tests) might detect viral components this early, antibody production usually takes more time.

Q: A man with chills, fever, and headache is thought to have "atypical" pneumonia. History reveals that he raises chickens, and that approximately 2 weeks ago he lost a large number of them to an undiagnosed disease. Which of the following is the most likely diagnosis of this man's condition?

Ornithosis. ***Ornithosis*** - The patient's symptoms of **chills, fever, headache, and atypical pneumonia**, combined with a history of **raising chickens** that recently died from an undiagnosed disease, are highly suggestive of ornithosis (also known as **psittacosis** or **parrot fever**). [2], [3] - This zoonotic infection is caused by **Chlamydophila psittaci** and is transmitted to humans through inhalation of contaminated aerosols from infected birds (poultry, parrots, pigeons). [2] *Leptospirosis* - **Leptospirosis** is typically associated with exposure to **contaminated water or soil** with animal urine, not direct contact with sick poultry. - While it can cause fever and headache, it often presents with **jaundice, renal failure, and hemorrhagic manifestations**, which are not mentioned here. *Relapsing fever* - **Relapsing fever** is characterized by **recurrent episodes of fever** separated by afebrile periods, caused by **Borrelia** species transmitted by lice or ticks. - The clinical presentation does not align with the typical course or epidemiological link to sick chickens. *Anthrax* - **Inhalational anthrax** can cause severe respiratory symptoms and fever but is primarily associated with exposure to **Bacillus anthracis spores**, often from infected livestock (cattle, sheep) or bioweapon exposure. [1] - The rapid death of a large number of chickens and the patient's "atypical pneumonia" do not fit the typical presentation or common transmission routes of anthrax. [1]

Q: The intracranial tumor most likely to be encountered in a middle-aged man with the acquired immunodeficiency syndrome (AIDS) is:

Lymphoma. ***Lymphoma*** - **Primary central nervous system lymphoma (PCNSL)** is the most common intracranial tumor in patients with acquired immunodeficiency syndrome (AIDS), particularly in those with a **CD4 count below 50 cells/mm³**. [1] - It is typically associated with **Epstein-Barr virus (EBV) infection** and presents with focal neurological deficits, cognitive changes, and seizures. [1] *Glioblastoma multiforme* - This is the most common primary brain tumor in the general population, but its incidence is **not specifically increased** in patients with AIDS. - While highly aggressive, its association with AIDS is **less direct** than lymphoma. *Meningioma* - Meningiomas are typically **benign tumors** arising from the meninges and are more common in older adults, especially women. - There is **no strong correlation** between meningioma incidence and AIDS. *Ependymoma* - Ependymomas are rare tumors that arise from **ependymal cells lining the ventricles** or central canal of the spinal cord, more commonly seen in children. - Their occurrence is **not specifically elevated** in individuals with AIDS.

Question 1

True about Mantoux is -

Accepted Answer

False negative in fulminant diseases

Answer

If once done, next time it is always positive

Answer

Results are given in terms of positive & negative

Answer

Indurations given in terms of length & breadth

Question 2

A 40-year-old man underwent kidney transplantation. Two months after transplantation, he developed fever and features suggestive of bilateral diffuse interstitial pneumonia. Which of the following is the most likely etiologic agent?

Accepted Answer

Cytomegalovirus

Answer

Varicella zoster virus

Answer

Herpes simplex virus

Answer

Epstein-barr virus

Question 3

The CSF findings in TB meningitis include –

Accepted Answer

Low sugar + high protein and Lymphocytosis

Answer

High sugar + high chloride

Answer

High sugar + low protein

Answer

Low sugar + high protein and Lymphopenia

Question 4

Pneumococcal meningitis is associated with the following CSF findings:

Accepted Answer

Pleocytosis with high protein and low sugar

Answer

Pleocytosis with low protein and low sugar

Answer

Lymphocytosis with low protein and low sugar

Answer

Lymphocytosis with high protein and low sugar

Question 5

Which of the following statements is true about dengue fever?
a) ↑ Hematocrit
b) ↓ Platelet
c) Positive tourniquet test
d) Vector (Aedes aegypti) usually bites in day time

Accepted Answer

Vector (Aedes aegypti) usually bites in day time

Answer

↑ Hematocrit

Answer

↓ Platelet

Answer

Positive tourniquet test

Question 6

Kissing disease is also known as

Accepted Answer

Glandular fever

Answer

Rubella

Answer

Scarlet fever

Answer

Acute herpetic gingivostomatitis

Question 7

Which of the following statements regarding classical Dengue fever is FALSE?

Accepted Answer

Positive tourniquet test

Answer

Low case fatality rate

Answer

Self limiting disease

Answer

Transmitted by Aedes aegypti

Question 8

Sero conversion in HIV Infection takes place in ?

Accepted Answer

4 weeks

Answer

12 weeks

Answer

9 weeks

Answer

2 weeks

Question 9

A man with chills, fever, and headache is thought to have "atypical" pneumonia. History reveals that he raises chickens, and that approximately 2 weeks ago he lost a large number of them to an undiagnosed disease. Which of the following is the most likely diagnosis of this man's condition?

Accepted Answer

Ornithosis

Answer

Leptospirosis

Answer

Relapsing fever

Answer

Anthrax

Question 10

The intracranial tumor most likely to be encountered in a middle-aged man with the acquired immunodeficiency syndrome (AIDS) is:

Accepted Answer

Lymphoma

Answer

Glioblastoma multiforme

Answer

Meningioma

Answer

Ependymoma

Infectious Diseases — MCQs

Infectious Diseases — MCQs

On this page

Practice by Chapter

Want unlimited practice?