Infectious Diseases Practice Questions

Q: The finding shown below is used for diagnosis of CNS parasitic lesion. Which of the following best describes the condition?

***Major criteria*** - The image likely depicts **multiple calcified cysts**, which in the context of CNS parasitic lesions (e.g., neurocysticercosis), would be considered a **major diagnostic criterion** for the disease. - Major criteria are significant findings, often radiographic evidence of **cysts or calcifications**, that strongly support a diagnosis of neurocysticercosis when combined with other criteria. *Minor criteria* - Minor criteria include less specific findings, such as **seizures** or headaches, or findings that support the diagnosis but are not definitive on their own. - While supportive, these findings are typically not sufficient for diagnosis without major or other criteria. *Absolute criteria* - Absolute criteria are definitive findings, such as a **histopathological demonstration of the parasite** or direct visualization of the scolex on imaging, which are direct proof of infection. - The image shows calcifications, which are strong evidence but not necessarily "absolute" proof of active parasitic presence without further context like a viable cyst with a scolex. *Epidemiological criteria* - Epidemiological criteria relate to the patient's **exposure history** or origin from areas endemic for the parasite. - These criteria help in narrowing down the differential diagnosis but do not provide direct evidence of the lesion itself.

Q: A patient undergone a Solid organ transplant is having the following lesions which are present on oral mucosa and sites shown below. Which of the following is incriminated in causing the same?

KSHV. ***KSHV*** - The image shows multiple **violaceous cutaneous lesions** which are characteristic of **Kaposi's sarcoma (KS)**. - In a solid organ transplant recipient, KS is commonly associated with **Kaposi's sarcoma-associated herpesvirus (KSHV)**, also known as HHV-8. Immunosuppression due to antirejection medications can reactivate latent KSHV infection. *HHV6* - HHV-6 is primarily associated with **roseola infantum** (exanthem subitum) in children. - While HHV-6 can cause complications in immunocompromised individuals, its typical manifestations do not involve the characteristic violaceous skin lesions seen in Kaposi's sarcoma. *HHV7* - HHV-7 is also associated with **roseola-like illnesses** and is generally considered a less pathogenic virus compared to other human herpesviruses. - It does not cause Kaposi's sarcoma, and its clinical manifestations in transplant patients are typically different from the lesions depicted. *CMV* - **Cytomegalovirus (CMV)** is a common opportunistic infection in solid organ transplant recipients, causing a variety of clinical syndromes. - While CMV can lead to numerous symptoms (e.g., fever, leukopenia, pneumonitis, colitis), it does not directly cause the characteristic skin lesions of Kaposi's sarcoma.

Q: A patient with HIV develops fever weight loss and diarrhea. Fecal examination shows isospora belli. He was given treatment with TMP - SMX. Diarrhea subsided but fever persisted. Bone marrow examination showed the following picture with intracellular fungi. Which of the following statements is wrong? (AIIMS Nov 2017)

It cannot be grown in SDA. ***It cannot be grown in SDA*** - The image shows **intracellular budding yeast** consistent with *Histoplasma capsulatum*. - *Histoplasma capsulatum* **can be cultured** on Sabouraud Dextrose Agar (SDA) as a mold at room temperature, making the statement that it cannot be grown in SDA incorrect. *Spores are infective form* - The infective form of *Histoplasma capsulatum* is indeed **microconidia (spores)**, which are inhaled into the lungs. - These spores convert to yeast forms in the host's body. *It is intracellular budding yeast* - The image clearly depicts **intracellular yeast cells within a macrophage**, a hallmark of *Histoplasma capsulatum* infection. - These yeast cells reproduce by **budding**, which is visible as smaller structures emerging from the main yeast cell. *It can cause systemic disease* - *Histoplasma capsulatum* is known to cause **histoplasmosis**, which can range from asymptomatic to severe disseminated disease, especially in **immunocompromised individuals like HIV patients**. - Systemic disease involves the spread of the fungus to organs beyond the lungs, such as the **bone marrow, liver, and spleen**, as evidenced by the bone marrow examination in the question.

Q: Which of the following statements are correct regarding Weil's disease? I. It is caused by a virus named leptospira II. Acute kidney injury can lead to oliguria in this disease III. Microscopic agglutination is the investigation of choice IV. Ceftriaxone given parenterally is effective treatment Select the correct answer using the code given below :

II, III and IV. ***II, III and IV*** - **Weil's disease**, a severe form of leptospirosis, frequently causes **acute kidney injury (AKI)**, which can manifest as **oliguria** due to renal tubular damage and interstitial nephritis [2]. - The **microscopic agglutination test (MAT)** is considered the gold standard for diagnosing leptospirosis due to its high specificity and sensitivity in detecting specific antibodies against *Leptospira* serovars [2]. - **Ceftriaxone** is an effective parenteral antibiotic for treating severe leptospirosis, including Weil's disease, particularly when oral antibiotics are insufficient or the patient is critically ill. *I, II and III* - Statement I is incorrect because Weil's disease is caused by a **spirochete bacterium**, *Leptospira interrogans*, not a virus [1]. - While statements II and III are correct regarding **AKI and oliguria** and the utility of **MAT**, the incorrectness of statement I makes this option wrong. *I, III and IV* - Statement I is incorrect as Weil's disease is caused by a **bacterium** (*Leptospira*), not a virus [1]. - While statements III and IV are correct, the presence of an incorrect statement (I) makes this composite option incorrect. *I, II and IV* - Statement I is factually incorrect; Weil's disease is caused by the **bacterium *Leptospira***, not a virus [1]. - Although statements II and IV are correct—**AKI with oliguria** is a feature and **ceftriaxone** is a treatment—the fundamental error in statement I invalidates this option.

Q: Which of the following statements are correct regarding Chikungunya fever ? 1. It is usually transmitted by Culex mosquito. 2. A safe and effective vaccine is available for commercial use. 3. Incubation period is 4 - 7 days. 4. One of the prominent symptoms is arthropathy. Select the correct answer using the code given below :

3 and 4 only. ***3 and 4 only*** - The incubation period for Chikungunya fever is typically **3-7 days**, with a range of 2-12 days, making 4-7 days a correct estimate. - **Arthropathy** (severe joint pain and swelling) is a hallmark symptom of Chikungunya fever, often presenting with polyarthralgia that can be debilitating and chronic. *1 and 4 only* - Chikungunya fever is primarily transmitted by **Aedes mosquitoes** (Aedes aegypti and Aedes albopictus), not Culex mosquitoes. - While arthropathy (statement 4) is a correct symptom, the transmission by Culex mosquito (statement 1) is incorrect. *2 and 3 only* - As of now, there is **no commercially available safe and effective vaccine** for Chikungunya fever, although several are in clinical trials. - While the incubation period (statement 3) is correct, the absence of a commercially available vaccine (statement 2) makes this option incorrect. *1 and 2 only* - Chikungunya is transmitted by **Aedes mosquitoes**, not Culex mosquitoes. - There is currently **no licensed vaccine** for Chikungunya available for widespread commercial use.

Q: Which of the following statements are correct regarding Mantoux test for tuberculosis? 1. It entails injecting 1 TU (Tuberculin Unit) of PPD (Purified Protein Derivative) in 0.1 mL intradermally. 2. The injection should be given with the needle bevel facing downward. 3. When placed correctly, the injection should produce a pale wheal of the skin, 1 - 2 mm in diameter. 4. The injection should be given with a tuberculin syringe. Select the correct answer using the code given below:

1 and 4. **1 and 4** - Statement 1 is correct: The Mantoux test involves injecting **1 TU (Tuberculin Unit) of PPD (Purified Protein Derivative)** in **0.1 mL intradermally** into the forearm, which is the standard dose and administration route. - Statement 4 is correct: A **tuberculin syringe** is specifically designed for small, precise volume injections like the Mantoux test, ensuring accurate dosing and placement. *1 and 2* - Statement 1 is correct, but statement 2 is incorrect regarding the **Mantoux test procedure**. - The needle bevel should face **upward** during intradermal injection to ensure proper placement of the PPD and formation of the wheal. *2 and 3* - Statement 2 is incorrect because the needle bevel should face **upward** for intradermal injection. - Statement 3 is incorrect because a correctly placed Mantoux injection should produce a wheal of **6-10 mm in diameter**, not 1-2 mm, indicating the PPD is in the dermis. *2 and 4* - Statement 2 is incorrect as the needle bevel should be positioned **facing upward**. - While statement 4 correctly identifies the use of a tuberculin syringe, the incorrectness of statement 2 makes this option unsuitable.

Q: Which one of the following is the commonest extra-salivary gland manifestation of mumps in adults?

Orchitis. **Orchitis** - **Orchitis**, the inflammation of the testes, is the most common extra-salivary gland manifestation of mumps in **post-pubertal males** and can lead to **testicular atrophy** and infertility. - The incidence of orchitis in adult males with mumps can be as high as 30–50%. *Pancreatitis* - While mumps can cause **pancreatitis**, it is less common than orchitis, occurring in only about 2-5% of cases [1]. - Mumps-induced pancreatitis is usually mild and self-limiting [1]. *Polyarthritis* - **Polyarthritis** is a rare complication of mumps, typically resolving without long-term sequelae. - It is much less frequently observed compared to orchitis, especially in adults. *Hydrocephalus* - **Hydrocephalus** is an extremely rare and severe complication of mumps, often associated with mumps **meningoencephalitis**. - This complication involves an abnormal accumulation of cerebrospinal fluid, which is highly uncommon following mumps infection.

Q: Mycetoma, a chronic, specific, granulomatous, destructive disease involving the skin and subcutaneous tissue:

may be caused by fungi or bacteria. ***may be caused by fungi or bacteria*** - Mycetoma can be caused by either **eumycetes (true fungi)**, leading to **eumycetoma**, or by certain **aerobic actinomycetes (bacteria)**, resulting in **actinomycetoma** [1]. - Both forms present with similar clinical features, including **granulomatous inflammation** and the formation of **grains** or granules. *involves the superficial structure only* - Mycetoma is characterized by its **destructive nature**, progressively involving **deep tissues** like fascia, muscle, and even bone, not just superficial structures [1]. - The disease often leads to **deformity** and **loss of function** due to deep tissue invasion. *frequently causes trophic changes* - While mycetoma leads to significant tissue destruction and deformity, **trophic changes** (e.g., changes in skin, hair, and nails due to nerve damage) are not its primary or most characteristic feature. - The main complications are related to **tissue destruction**, **secondary infections**, and **amputation**. *is a blood-borne infection* - Mycetoma is acquired through **traumatic inoculation** of the causative organism into the skin, typically via thorns or splinters. - It is a **localized infection** and does not spread via the bloodstream; systemic dissemination is very rare.

Q: The complications of ascaris lumbricoides infestation include all of the following except :

peptic ulcer disease. ***Peptic ulcer disease*** - **Peptic ulcer disease** is not a commonly recognized direct complication of *Ascaris lumbricoides* infestation. - While *Ascaris* can cause gastrointestinal symptoms, it does not typically lead to the formation of peptic ulcers. *Lower gastrointestinal bleed* - Heavy worm burdens can cause irritation and inflammation of the intestinal lining, potentially leading to **mucosal erosions** and **lower gastrointestinal bleeding**. - In rare cases, worms might erode into blood vessels, contributing to bleeding. *Cholangitis and obstructive jaundice* - Adult worms can migrate from the small intestine into the **biliary tree**, obstructing bile flow and causing **cholangitis** or **obstructive jaundice**. - They can also enter the pancreatic duct, leading to **pancreatitis**. *Acute intestinal obstruction* - A large bolus of adult worms can form a tangled mass (bolus) within the small intestine, leading to **complete or partial acute intestinal obstruction**. - This is a serious surgical emergency, especially in children with heavy worm loads.

Q: The most common opportunistic infection observed in patients with AIDS is

Pneumocystis carinii. ***Pneumocystis carinii*** - **Pneumocystis pneumonia (PCP)**, caused by *Pneumocystis jirovecii* (formerly *P. carinii*), is the **most common opportunistic infection** and a leading cause of death in AIDS patients [1]. - It typically presents with **fever, cough, and dyspnea** in patients with a CD4 count below 200 cells/µL [1]. *Pseudomonas aeruginosa* - While *Pseudomonas aeruginosa* can cause serious infections in immunocompromised individuals, it is not the **most common opportunistic infection** seen in patients with AIDS. - Infections usually involve the **lungs (pneumonia)**, skin, urinary tract, or bacteremia, often in patients with **neutropenia** or hospitalized for other reasons. *Atypical mycobacteria* - **Mycobacterium avium complex (MAC)** is an important opportunistic pathogen in AIDS patients (CD4 < 50 cells/µL), causing disseminated disease, but it is not the **most common** overall [2]. - Symptoms include **fever, weight loss, night sweats, and diarrhea**, and diagnosis requires blood cultures or tissue biopsy [2]. *Haemophilus influenzae* - *Haemophilus influenzae* can cause **respiratory tract infections** (e.g., sinusitis, bronchitis, pneumonia) and invasive disease, particularly in children and individuals with underlying lung disease. - While patients with HIV may be more susceptible to bacterial infections, *H. influenzae* is **not classified as a classic opportunistic infection** in the same way as *Pneumocystis* or MAC in AIDS patients.

Question 1

The finding shown below is used for diagnosis of CNS parasitic lesion. Which of the following best describes the condition?

Answer

Minor criteria

Answer

Absolute criteria

Answer

Epidemiological criteria

Answer

Major criteria

Question 2

A patient undergone a Solid organ transplant is having the following lesions which are present on oral mucosa and sites shown below. Which of the following is incriminated in causing the same?

Accepted Answer

KSHV

Answer

HHV6

Answer

HHV7

Answer

CMV

Question 3

A patient with HIV develops fever weight loss and diarrhea. Fecal examination shows isospora belli. He was given treatment with TMP - SMX. Diarrhea subsided but fever persisted. Bone marrow examination showed the following picture with intracellular fungi. Which of the following statements is wrong? (AIIMS Nov 2017)

Accepted Answer

It cannot be grown in SDA

Answer

Spores are infective form

Answer

It is intracellular budding yeast

Answer

It can cause systemic disease

Question 4

Which of the following statements are correct regarding Weil's disease?
I. It is caused by a virus named leptospira
II. Acute kidney injury can lead to oliguria in this disease
III. Microscopic agglutination is the investigation of choice
IV. Ceftriaxone given parenterally is effective treatment

Select the correct answer using the code given below :

Accepted Answer

II, III and IV

Answer

I, II and III

Answer

I, III and IV

Answer

I, II and IV

Question 5

Which of the following statements are correct regarding Chikungunya fever ?

1. It is usually transmitted by Culex mosquito.
2. A safe and effective vaccine is available for commercial use.
3. Incubation period is 4 - 7 days.
4. One of the prominent symptoms is arthropathy.

Select the correct answer using the code given below :

Accepted Answer

3 and 4 only

Answer

1 and 4 only

Answer

2 and 3 only

Answer

1 and 2 only

Question 6

Which of the following statements are correct regarding Mantoux test for tuberculosis?

1. It entails injecting 1 TU (Tuberculin Unit) of PPD (Purified Protein Derivative) in 0.1 mL intradermally.
2. The injection should be given with the needle bevel facing downward.
3. When placed correctly, the injection should produce a pale wheal of the skin, 1 - 2 mm in diameter.
4. The injection should be given with a tuberculin syringe.

Select the correct answer using the code given below:

Accepted Answer

1 and 4

Answer

1 and 2

Answer

2 and 3

Answer

2 and 4

Question 7

Which one of the following is the commonest extra-salivary gland manifestation of mumps in adults?

Accepted Answer

Orchitis

Answer

Pancreatitis

Answer

Polyarthritis

Answer

Hydrocephalus

Question 8

Mycetoma, a chronic, specific, granulomatous, destructive disease involving the skin and subcutaneous tissue:

Accepted Answer

may be caused by fungi or bacteria

Answer

involves the superficial structure only

Answer

frequently causes trophic changes

Answer

is a blood-borne infection

Question 9

The complications of ascaris lumbricoides infestation include all of the following except :

Accepted Answer

peptic ulcer disease

Answer

lower gastro intestinal bleed

Answer

cholangitis and obstructive jaundice

Answer

acute intestinal obstruction

Question 10

The most common opportunistic infection observed in patients with AIDS is

Accepted Answer

Pneumocystis carinii

Answer

Pseudomonas aeruginosa

Answer

Atypical mycobacteria

Answer

Haemophilus influenzae

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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