Infectious Diseases Practice Questions

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 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 is NOT a characteristic of Dengue shock syndrome?

Decreased haemoglobin. ***Decreased haemoglobin*** - **Decreased hemoglobin** is *not* a characteristic feature of Dengue shock syndrome; rather, **hemoconcentration**, indicated by an *increased* hematocrit, is a hallmark due to plasma leakage. - While bleeding can occur in dengue, leading to decreased hemoglobin, **hemoconcentration** is a more direct and consistent sign of severe plasma leakage in Dengue Shock Syndrome [1]. *Hepatomegaly* - **Hepatomegaly** (enlarged liver) is a common finding in severe dengue, including Dengue Shock Syndrome, due to hepatic inflammation and dysfunction [1]. - This symptom reflects the systemic nature of the infection and can contribute to abdominal pain and tenderness. *Pleural effusion* - **Pleural effusion** is a key indicator of **plasma leakage**, a defining characteristic of severe dengue and Dengue Shock Syndrome [1]. - The effusion results from fluid transudation into the pleural space, often accompanied by ascites. *Thrombocytopenia* - **Thrombocytopenia** (low platelet count) is a consistent and serious finding in dengue, particularly in severe forms like Dengue Shock Syndrome [1]. - A significant drop in platelet count often precedes or accompanies the onset of shock and increases the risk of bleeding.

Q: What is the commonest form of plague?

Bubonic plague. ***Bubonic plague*** - This is the **most common** form of plague, accounting for the majority of human cases [1]. - It is characterized by the development of painful, swollen lymph nodes called **buboes**, typically in the groin, armpit, or neck. *Pneumonic plague* - This form affects the **lungs** and is less common, but it is the most **virulent** and can be transmitted directly from person to person via respiratory droplets [1]. - If left untreated, bubonic or septicaemic plague can progress to secondary pneumonic plague [1]. *Septicaemic plague* - This form occurs when the bacteria **multiply in the bloodstream**, leading to widespread infection and potentially septic shock [1]. - It is less common than bubonic plague and can occur as a primary infection or as a complication of untreated bubonic plague [1]. *Hemorrhagic plague* - While plague can cause **hemorrhage** due to disseminated intravascular coagulation, "hemorrhagic plague" is not a distinct, recognized form of plague. - Bleeding is a **symptom** that can occur in severe cases of septicaemic or pneumonic plague, indicating extensive organ damage.

Q: Which of the following is NOT an extrahepatic manifestation of Hepatitis C?

Celiac Disease. ***Celiac Disease*** - Celiac disease is an **autoimmune disorder** triggered by gluten, not associated with Hepatitis C. [1] - Extrahepatic manifestations of Hepatitis C typically include **dermatological and rheumatological conditions**, which are absent in celiac disease. *Cryoglobulinemia* - Cryoglobulinemia is a common **extrahepatic manifestation** of Hepatitis C, often leading to **vasculitis**. - It presents with **skin rashes**, arthralgia, and renal issues, significantly associated with chronic Hepatitis C infection [2]. *Lichen Planus* - Lichen Planus is another **dermatological condition** frequently linked with Hepatitis C, manifesting with **itchy lesions** on skin and mucous membranes. - The exact mechanism is unclear, but it shows a significant correlation with the virus. *Glomerulonephritis* - Glomerulonephritis is also recognized as a potential **extrahepatic complication** of Hepatitis C, often resulting from **cryoglobulinemic vasculitis**. - It can lead to symptoms of **nephritis**, such as hematuria and proteinuria, reflecting kidney involvement [2].

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: 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: 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.

Question 1

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 2

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 3

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 4

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

Question 5

Which of the following is NOT a characteristic of Dengue shock syndrome?

Accepted Answer

Decreased haemoglobin

Answer

Pleural effusion

Answer

Thrombocytopenia

Answer

Hepatomegaly

Question 6

What is the commonest form of plague?

Accepted Answer

Bubonic plague

Answer

Pneumonic plague

Answer

Septicaemic plague

Answer

Hemorrhagic plague

Question 7

Which of the following is NOT an extrahepatic manifestation of Hepatitis C?

Accepted Answer

Celiac Disease

Answer

Glomerulonephritis

Answer

Cryoglobulinemia

Answer

Lichen Planus

Question 8

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 9

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 10

Bloody diarrhea in HIV infected patient is mostly due to ?

Accepted Answer

CMV

Answer

Cryptosporidium

Answer

Isospora

Answer

Salmonella

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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