Infectious Diseases Practice Questions

Q: Tuberculosis of spine most commonly affects which vertebral segment?

Lower dorsal. ***Lower dorsal*** - The **lower dorsal** (thoracic) spine, especially T9-T12, is the most frequently affected segment in **tuberculosis of the spine** (Pott's disease) [1]. - This region's rich vascular supply, particularly the nutrient arteries, makes it a common site for hematogenous spread of *Mycobacterium tuberculosis*. *Upper dorsal* - While other segments can be affected, the **upper dorsal spine** is less commonly involved than the lower dorsal region. - Involvement here might present with similar symptoms but is statistically less frequent. *Lumbar* - The **lumbar spine** is the second most common site for spinal tuberculosis, but it is still less frequent than the lower dorsal region [1]. - Lumbar involvement typically presents with **low back pain** and neurological deficits but is not the primary site. *Cervical* - **Cervical spine** involvement in tuberculosis is rare, accounting for a small percentage of all spinal TB cases. - It can lead to severe neurological compromise due to the **narrow spinal canal** in this region.

Q: CCR5 mutation is related to which condition ?

Resistance to HIV infection. ***Resistance to HIV infection*** - A specific mutation, **CCR5-delta32**, leads to a non-functional **CCR5 receptor** on the surface of immune cells. - Since **HIV** primarily uses the **CCR5 receptor** to enter target cells, individuals with this mutation are highly resistant to HIV infection. *Susceptibility to HIV infection* - A functional **CCR5 receptor** is required for most **HIV** strains (R5 strains) to enter human cells. - Mutations leading to a non-functional **CCR5 receptor** decrease, rather than increase, susceptibility to HIV. *Resistance to HBV infection* - The **hepatitis B virus (HBV)** uses different cellular receptors for entry, primarily the **sodium taurocholate co-transporting polypeptide (NTCP)**. - **CCR5** mutations have no known effect on susceptibility or resistance to **HBV infection**. *Susceptibility to HBV infection* - Susceptibility to **HBV** infection is determined by the presence and functionality of its specific entry receptors, such as NTCP. - **CCR5** mutations do not impact these pathways and therefore do not influence susceptibility to **HBV**.

Q: Which of the following is an ocular complication associated with Zika virus infection?

Eye inflammation. ***Eye inflammation*** - **Ocular manifestations** are recognized complications of **Zika virus infection**, ranging from conjunctivitis to more severe conditions like **uveitis** and **optic neuritis**. - Specifically, **chorioretinal scars** and **optic nerve abnormalities** have been observed in infants with congenital Zika syndrome. *Liver inflammation* - **Hepatitis**, or liver inflammation, is not a common or specific complication directly associated with Zika virus infection. - While some viral infections can affect the liver, **Zika** primarily targets **neural tissues** and has specific ocular and neurological complications. *Heart inflammation* - **Myocarditis**, or heart inflammation, is not a frequently reported or characteristic complication of **Zika virus infection**. - The primary systemic manifestations of **Zika** typically involve **mild fever**, **rash**, **arthralgia**, and **conjunctivitis**, with severe outcomes usually being neurological. *None of the options* - This option is incorrect because **eye inflammation** is a well-documented and significant ocular complication of **Zika virus infection**. - The virus is known to have **tropism for ocular tissues**, leading to various visual impairments.

Q: Which of the following is a known risk factor for cholangiocarcinoma?

Clonorchis sinensis infestation. ***Clonorchis sinensis infestation*** - **Clonorchis sinensis**, also known as the Chinese liver fluke, is a well-established and significant risk factor for the development of **cholangiocarcinoma**. - Chronic inflammation and irritation of the bile ducts caused by the parasite are believed to promote malignant transformation. *Giardia lamblia (intestinal protozoa) infection* - **Giardia lamblia** is a common intestinal parasite causing giardiasis, characterized by diarrhea and malabsorption. - While it affects the gastrointestinal tract, there is **no known association** between *Giardia* infection and an increased risk of cholangiocarcinoma. *Paragonimus westermani infestation* - **Paragonimus westermani** is a lung fluke that primarily causes paragonimiasis, affecting the lungs and leading to cough and hemoptysis. - This parasite is not associated with direct bile duct inflammation or an increased risk of **cholangiocarcinoma**. *Ascaris lumbricoides (roundworm) infection* - **Ascaris lumbricoides** is a large intestinal roundworm that can cause intestinal obstruction or nutrient deficiencies. - Although it can occasionally migrate into the biliary tree, it is **not considered a risk factor** for cholangiocarcinoma [1].

Q: Which of the following organisms is not typically associated with causing chronic adrenal insufficiency?

Mycobacterium bovis. ***Mycobacterium bovis*** - While *Mycobacterium bovis* can cause tuberculosis-like disease, it is **less commonly associated with chronic adrenal insufficiency** compared to *M. tuberculosis* itself, which has a predilection for adrenal tissue. - Infection with *M. bovis* primarily affects cattle and can be transmitted to humans, but its tropism for the adrenal glands leading to insufficiency is not a primary recognized feature. *Mycobacterium tuberculosis* - **Tuberculosis** is a well-known cause of chronic adrenal insufficiency, also known as **Addison's disease**, particularly in endemic regions. [1] - The bacteria can directly infect and destroy the adrenal cortex, leading to impaired hormonal production. *Histoplasma capsulatum* - **Disseminated histoplasmosis**, especially in immunocompromised individuals, can directly involve the adrenal glands. - This fungal infection can lead to **adrenal destruction and chronic adrenal insufficiency** by granuloma formation and necrosis. *Coccidioides immitis* - **Disseminated coccidioidomycosis** is another fungal infection that can cause adrenal gland involvement. - Similar to histoplasmosis, it can lead to **granulomatous inflammation and necrosis** within the adrenal cortex, resulting in chronic adrenal insufficiency.

Q: Bloody diarrhea in HIV infected patient is mostly due to ?

CMV. ***CMV*** - **Cytomegalovirus (CMV) colitis** is a common opportunistic infection in advanced HIV, causing **bloody diarrhea**, abdominal pain, and fever. - CMV infection can lead to **ulcerations** and inflammation of the colonic mucosa, resulting in blood in the stool. *Cryptosporidium* - **Cryptosporidiosis** causes profuse, **watery diarrhea** in HIV patients, not typically bloody [1]. - While it can be severe and persistent, it primarily affects the small intestine, leading to malabsorption. *Isospora* - **Isosporiasis** (caused by *Isospora belli*) primarily presents as **unrelenting watery diarrhea** in immunocompromised individuals [1]. - It affects the small bowel and does not commonly result in bloody stools. *Salmonella* - **Salmonella gastroenteritis** can cause bloody diarrhea, but in HIV patients, it is often associated with **bacteremia** and systemic infection. - While possible, **CMV colitis** is a more classic and frequent cause of bloody diarrhea in advanced HIV in the absence of other focal symptoms.

Q: Which hepatitis infection is most commonly associated with immune thrombocytopenic purpura?

Hepatitis C infection. ***Hepatitis C infection*** - **Hepatitis C** is well-established for causing various **extrahepatic manifestations**, including mixed cryoglobulinemia, membranoproliferative glomerulonephritis, and **immune thrombocytopenic purpura (ITP)**. - The mechanism involves chronic viral stimulation leading to the production of **autoantibodies** against platelets and megakaryocytes, or direct viral effects on bone marrow. *Hepatitis A infection* - **Hepatitis A** is an **acute, self-limiting viral infection** [1] that typically does not lead to chronic liver disease or significant extrahepatic manifestations like ITP. - There are rare reports of transient thrombocytopenia in acute hepatitis A, but it is not commonly associated with chronic ITP. *Hepatitis B infection* - While **Hepatitis B** can cause extrahepatic manifestations such as polyarteritis nodosa and glomerulonephritis, its association with **immune thrombocytopenic purpura (ITP)** is less frequent and not as strong as with Hepatitis C. - HBV-associated thrombocytopenia is more often related to **hypersplenism** in cirrhotics or direct viral bone marrow suppression, rather than immune-mediated destruction. *Hepatitis D infection* - **Hepatitis D (HDV)** is a **defective virus** that requires co-infection with Hepatitis B virus (HBV) to replicate. - Its extrahepatic manifestations are primarily linked to the underlying **HBV infection**, and there is no strong, independent association with immune thrombocytopenic purpura.

Q: Which of the following statements about epididymo-orchitis of mumps is incorrect?

It is the most common manifestation of mumps infection. ***It is the most common manifestation of mumps infection*** - This statement is **INCORRECT**. The most common manifestation of mumps infection is **parotitis** (inflammation of the parotid glands), not epididymo-orchitis. - About **one-third of mumps infections are asymptomatic**, and **orchitis** occurs in only 20-30% of post-pubertal males with mumps. - Epididymo-orchitis is a significant complication but not the predominant presentation. *Testicular enlargement usually resolves in 1 week* - This statement is correct. The **swelling and tenderness** of mumps orchitis typically resolve within **3-7 days** (approximately 1 week). - The acute phase of inflammation and pain generally subsides within this timeframe, though complete resolution may take longer. *Complete sterility is a rare outcome in these patients.* - This statement is correct. While mumps orchitis can cause **testicular atrophy** and **impaired spermatogenesis**, **complete sterility is rare**. - Even with bilateral involvement, some degree of fertility is usually preserved as not all seminiferous tubules are damaged. *Bilateral testicular involvement is seen in 10-30% of cases.* - This statement is correct. Mumps orchitis is predominantly **unilateral**, with **bilateral involvement** occurring in approximately **10-30%** of affected individuals. - Most cases involve only one testis, reducing the risk of severe fertility impairment.

Question 1

Tuberculosis of spine most commonly affects which vertebral segment?

Accepted Answer

Lower dorsal

Answer

Upper dorsal

Answer

Lumbar

Answer

Cervical

Question 2

Following are the features of neuropathy associated with varicella-zoster infection, which of the following is true?

Accepted Answer

Shingles are distributed along sensory dermatomes.

Answer

Upon reactivation, the virus is transported along sensory nerves to the skin, causing neuropathic symptoms.

Answer

Intranuclear inclusions, a hallmark of herpesvirus infections, are found in the peripheral nervous system during VZV neuropathy.

Answer

Persistent infection in neurons of sensory ganglia is a key feature of varicella-zoster virus pathophysiology.

Question 3

CCR5 mutation is related to which condition ?

Accepted Answer

Resistance to HIV infection

Answer

Susceptibility to HIV infection

Answer

Resistance to HBV infection

Answer

Susceptibility to HBV infection

Question 4

Which of the following is an ocular complication associated with Zika virus infection?

Accepted Answer

Eye inflammation

Answer

Liver inflammation

Answer

Heart inflammation

Answer

None of the options

Question 5

Which of the following is a known risk factor for cholangiocarcinoma?

Accepted Answer

Clonorchis sinensis infestation

Answer

Giardia lamblia (intestinal protozoa) infection

Answer

Ascaris lumbricoides (roundworm) infection

Answer

Paragonimus westermani infestation

Question 6

Which of the following organisms is not typically associated with causing chronic adrenal insufficiency?

Accepted Answer

Mycobacterium bovis

Answer

Histoplasma capsulatum

Answer

Coccidioides immitis

Answer

Mycobacterium tuberculosis

Question 7

Bloody diarrhea in HIV infected patient is mostly due to ?

Accepted Answer

CMV

Answer

Cryptosporidium

Answer

Isospora

Answer

Salmonella

Question 8

Which hepatitis infection is most commonly associated with immune thrombocytopenic purpura?

Accepted Answer

Hepatitis C infection

Answer

Hepatitis A infection

Answer

Hepatitis B infection

Answer

Hepatitis D infection

Question 9

Which of the following statements about epididymo-orchitis of mumps is incorrect?

Accepted Answer

It is the most common manifestation of mumps infection

Answer

Testicular enlargement usually resolves in 1 week

Answer

Complete sterility is a rare outcome in these patients.

Answer

Bilateral testicular involvement is seen in 10-30% of cases.

Question 10

Major criteria for infective endocarditis include which of the following

Accepted Answer

Isolation of a typical organism from two separate blood cultures

Answer

History of injection drug use

Answer

Presence of Osler's nodes

Answer

Persistent fever for more than 4 days

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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