Virology Practice Questions

Q: Roseola infantum is caused by ______

HHV 6. ***HHV 6*** - **Roseola infantum**, also known as **exanthem subitum**, is characteristically caused by **Human Herpesvirus 6 (HHV 6)**. - This virus typically causes an illness in infants and young children featuring a **high fever for several days** followed by a **maculopapular rash** after the fever subsides. *Rubeola* - **Rubeola** is the virus responsible for **measles**, a disease distinctly different from roseola with prominent symptoms like **Koplik spots** and a rash that appears during the fever. - Measles rash typically starts on the face and spreads downwards, while roseola rash appears after the fever breaks. *Rubella* - **Rubella** causes **German measles**, characterized by a **milder rash** and relatively few systemic symptoms compared to measles. - Unlike roseola, rubella's rash often appears coincident with or shortly after the fever, and the fever is generally not as high. *HHV 5* - **HHV 5** refers to **Cytomegalovirus (CMV)**, which is associated with a wide range of clinical manifestations, including congenital infections, mononucleosis-like syndrome, and opportunistic infections in immunocompromised individuals. - CMV typically does not cause the classic fever-then-rash presentation seen in roseola infantum.

Q: In HIV patients, Kaposi's sarcoma is most likely caused by which of the following?

Virus. ***Virus*** - The image likely depicts **Kaposi's sarcoma**, a common lesion in HIV patients, which is caused by **Human Herpesvirus 8 (HHV-8)**. - Other viral infections like **Herpes Simplex Virus (HSV)** can also cause mucocutaneous lesions in immunocompromised individuals. *Bacteria* - While HIV patients are susceptible to bacterial infections (e.g., **Staphylococcus aureus** causing skin abscesses), the described lesion type is not characteristic of common bacterial skin infections. - Bacterial lesions often present as pustules, cellulitis, or ulcers with purulent discharge, which differ from typical Kaposi's sarcoma. *Parasite* - Parasitic infections can occur in HIV patients (e.g., **scabies** or **leishmaniasis**), but these typically present with different dermatological features like intensely itchy papules or nodular ulcerative lesions. - Lesions caused by parasites do not usually manifest as the violaceous, nodular, or plaque-like appearances seen in Kaposi's sarcoma. *Fungus* - Fungal infections in HIV patients can cause skin lesions (e.g., **candidiasis** with oral thrush or esophagitis, or **cryptococcosis** with molluscum-like lesions). - However, the morphology of these fungal lesions generally differs from the classic appearance of Kaposi's sarcoma or other common viral lesions in HIV.

Q: Which of the following is NOT a characteristic of hepatitis B infection?

HBcAg in serum indicate active infection. Hepatitis B core antigen (HBcAg) is found within the infected hepatocytes and is not secreted into the bloodstream [1]. The presence of HBcAg in serum would typically indicate a ruptured hepatocyte and damaged liver, but it is not a routine marker for active infection. Alpha interferon is a common antiviral medication used in the treatment of chronic hepatitis B infection [1]. Its mechanism of action involves modulating the immune system to clear the virus and prevent liver damage. Perinatal transmission of hepatitis B is a major route, and infants infected at birth have a high risk (up to 90%) of developing chronic hepatitis B [1]. Their immature immune systems often fail to clear the virus, leading to persistent infection. Chronic hepatitis B infection is a significant risk factor for developing hepatocellular carcinoma (HCC) [1]. The persistent inflammation and liver damage associated with chronic infection promote cellular dysplasia and malignant transformation.

Q: Most sensitive test for diagnosis of infectious mononucleosis:

Paul Bunnel test. ***Paul Bunnel test*** - The **Paul-Bunnell test** detects heterophile antibodies by agglutinating sheep red blood cells, which are characteristic of infectious mononucleosis. - While largely replaced by the **Monospot test**, it is historically known for its **sensitivity** in detecting these antibodies. *Monospot test* - The **Monospot test** is a rapid, widely used test for infectious mononucleosis that detects **heterophile antibodies**, but its sensitivity is lower in the early stages of the disease. - Although convenient, it can produce **false negatives**, especially in young children or very early in the infection. *Culture of the virus* - **Culturing Epstein-Barr virus (EBV)**, the causative agent of infectious mononucleosis, is **not practical for routine diagnosis** due to its technical complexity and long turnaround time [1]. - Viral culture is typically reserved for **research purposes** rather than clinical diagnosis [1]. *Lymphocytosis in peripheral smear* - While **atypical lymphocytosis** (more than 10% atypical lymphocytes) on a peripheral smear is a **characteristic finding** in infectious mononucleosis, it is **not specific** for the condition [1]. - This finding can also be present in other viral infections and does not confirm the diagnosis on its own; it serves as a **supportive indicator** [1].

Q: Genital warts are caused by:

Human Papilloma Virus. ***Human Papilloma Virus*** - **Human Papilloma Virus (HPV)** is the primary cause of genital warts, particularly low-risk types like **HPV-6** and **HPV-11**. - HPV infection is common and is transmitted primarily through **sexual contact**. *Chlamydia trachomatis* - **Chlamydia trachomatis** is a bacterium that causes a common sexually transmitted infection (STI), leading to **urethritis**, **cervicitis**, and pelvic inflammatory disease, but not genital warts. - It can cause symptoms like **dysuria** and **vaginal discharge**, or be asymptomatic, but does not result in wart-like lesions. *Epstein Barr virus* - **Epstein-Barr virus (EBV)** is a herpesvirus primarily known for causing **infectious mononucleosis** (glandular fever). - It is associated with certain cancers like nasopharyngeal carcinoma and lymphomas but not with sexually transmitted genital warts. *HSV* - **Herpes Simplex Virus (HSV)** causes **genital herpes**, characterized by painful **blisters** and **sores** that typically recur. - While HSV is a sexually transmitted infection, the lesions it causes are vesicular and ulcerative, distinctly different from the fleshy, wart-like lesions of HPV.

Q: Which of the following is the most common clinical manifestation of human parvovirus B19?

Erythema infectiosum. ***Erythema infectiosum*** - This is also known as **fifth disease** and is characterized by a "slapped cheek" rash on the face followed by a lacy rash on the trunk and limbs. - It is a common and usually mild illness in children, caused by **human parvovirus B19**. *Hydrops fetalis* - While parvovirus B19 can cause hydrops fetalis in pregnant women by infecting fetal red blood cell precursors, it is a severe, less common manifestation rather than a **common clinical presentation** across all infected individuals. - Hydrops fetalis is characterized by **extensive fetal edema** and effusions, leading to high mortality. *Aplastic crisis in hemolytic anemia patients* - Parvovirus B19 can cause transient aplastic crisis, especially in individuals with **pre-existing hemolytic anemias** (e.g., sickle cell disease), due to its tropism for erythroid progenitor cells. - However, this is a specific complication in a susceptible population, not the **most common clinical manifestation** in the general population. *Anemia in neonatal period* - Parvovirus B19 infection can cause severe anemia in newborns if the mother is infected during pregnancy. - However, direct infection causing anemia in the neonatal period is less common than erythema infectiosum, which is widespread in children.

Q: Most common organism causing chronic complications in allograft transplant recipients:

Virus. ***Virus*** - Viruses, particularly **cytomegalovirus (CMV)**, **Epstein-Barr virus (EBV)**, and **BK virus**, are common causes of chronic complications such as **allograft dysfunction**, **post-transplant lymphoproliferative disorder (PTLD)**, and **nephropathy** in transplant recipients [1], [2]. - The immunocompromised state of transplant patients due to immunosuppressive therapy makes them highly susceptible to reactivation of latent viral infections or new viral exposures, leading to long-term morbidities [2]. *Bacteria* - While **bacterial infections** are common in the early post-transplant period, leading to acute complications such as **pneumonia** or **surgical site infections**, they are less frequently the primary cause of chronic complications directly affecting allograft survival over the long term [1]. - Patients can still get chronic bacterial infections, but their impact on overall chronic allograft complications is not as widespread as that of viral infections. *Fungi* - **Fungal infections** can cause severe, disseminated disease in immunocompromised transplant recipients and are associated with high mortality [1]. - However, they are generally less frequent than viral infections and tend to lead to more acute, severe complications rather than chronic allograft dysfunction in the broader transplant population. *Parasite* - **Parasitic infections** are relatively uncommon in transplant recipients in developed countries, although they can cause significant morbidity and mortality, especially in endemic regions. - They are not considered the most common cause of general chronic complications affecting allograft recipients.

Q: Shingles is caused by infection with:

Varicella zoster virus. ***Varicella zoster virus*** - **Varicella zoster virus (VZV)** is the causative agent of both **chickenpox** (varicella) and **shingles** (herpes zoster). - Shingles occurs due to the **reactivation** of latent VZV from sensory ganglia, years after a primary chickenpox infection. *Epstein-Barr virus* - **Epstein-Barr virus (EBV)** is responsible for **infectious mononucleosis** and is associated with several malignancies. - It does not cause shingles or any other **herpes zoster**-like syndrome. *Human papilloma virus* - **Human papilloma virus (HPV)** is known for causing **warts** and is a primary cause of **cervical cancer**. - HPV is not related to the pathogenesis of shingles. *Herpes simplex virus* - **Herpes simplex virus (HSV)** causes **oral herpes** (cold sores) and **genital herpes**. - While it belongs to the same family (Herpesviridae) as VZV, it causes different clinical manifestations and is distinct from the virus causing shingles.

Q: Which is the most common mode of transmission of HSV-1?

Saliva. ***Saliva*** - HSV-1 is primarily transmitted through **oral secretions**, such as saliva, due to close personal contact like **kissing** or sharing utensils. - The virus is present in the saliva of infected individuals, even in the absence of active lesions, facilitating its widespread transmission. *Placental transmission* - While possible, **vertical transmission** of HSV (primarily HSV-2) from mother to fetus via the placenta is rare and typically leads to **neonatal herpes**, not the most common mode of HSV-1 infection. - This mode is more characteristic of infections like **cytomegalovirus** or **syphilis**. *Sexual transmission* - While HSV-1 can cause **genital herpes** and be transmitted sexually, it is not its most common mode of acquisition, especially in childhood. - **HSV-2** is the primary cause of genital herpes and is predominantly transmitted through sexual contact. *Blood* - HSV is not typically transmitted through **blood transfusions** or contact with blood products. - While theoretical, **viremia** (virus in the blood) in HSV infections is transient and less significant for transmission compared to direct contact with active lesions or secretions.

Q: Influenza pandemics are most commonly caused by-

Influenza-A. ***Influenza-A*** - **Influenza A viruses** are responsible for causing **all known influenza pandemics** due to their ability to undergo **antigenic shift**. - Antigenic shift involves major genetic reassortment, particularly in the hemagglutinin (H) and neuraminidase (N) surface proteins, allowing the virus to evade host immunity and cause widespread infection. - Historical pandemics (1918 Spanish flu, 1957 Asian flu, 1968 Hong Kong flu, 2009 H1N1) were all caused by Influenza A. *Influenza-C* - **Influenza C viruses** are generally associated with **mild, self-limiting respiratory illnesses** and do not typically cause epidemics or pandemics. - The genome of Influenza C viruses is less prone to the significant genetic changes necessary to cause pandemics. *Influenza-D* - **Influenza D viruses** primarily infect **cattle and other livestock** and have not been shown to cause human infections. - They are not associated with human epidemics or pandemics. *Influenza-B* - While **Influenza B viruses** can cause seasonal epidemics, they do not undergo **antigenic shift** to the same extent as Influenza A. - Influenza B viruses only circulate in humans and lack the animal reservoir necessary for major reassortment events. - This limited genetic variability means they are **not typically associated with pandemics**.

Question 1

Roseola infantum is caused by ______

Accepted Answer

HHV 6

Answer

Rubeola

Answer

Rubella

Answer

HHV 5

Question 2

In HIV patients, Kaposi's sarcoma is most likely caused by which of the following?

Accepted Answer

Virus

Answer

Bacteria

Answer

Parasite

Answer

Fungus

Question 3

Which of the following is NOT a characteristic of hepatitis B infection?

Accepted Answer

HBcAg in serum indicate active infection

Answer

Alpha interferon is used for the treatment of chronic infection

Answer

Establishes chronic infections in those infected as infants

Answer

Can cause hepatocellular carcinoma

Question 4

Most sensitive test for diagnosis of infectious mononucleosis:

Accepted Answer

Paul Bunnel test

Answer

Monospot test

Answer

Culture of the virus

Answer

Lymphocytosis in peripheral smear

Question 5

Genital warts are caused by:

Accepted Answer

Human Papilloma Virus

Answer

Chlamydia trachomatis

Answer

Epstein Barr virus

Answer

HSV

Question 6

Which of the following is the most common clinical manifestation of human parvovirus B19?

Accepted Answer

Erythema infectiosum

Answer

Hydrops fetalis

Answer

Aplastic crisis in hemolytic anemia patients

Answer

Anemia in neonatal period

Question 7

Most common organism causing chronic complications in allograft transplant recipients:

Accepted Answer

Virus

Answer

Bacteria

Answer

Fungi

Answer

Parasite

Question 8

Shingles is caused by infection with:

Accepted Answer

Varicella zoster virus

Answer

Epstein-Barr virus

Answer

Human papilloma virus

Answer

Herpes simplex virus

Question 9

Which is the most common mode of transmission of HSV-1?

Accepted Answer

Saliva

Answer

Placental transmission

Answer

Sexual transmission

Answer

Blood

Question 10

Influenza pandemics are most commonly caused by-

Accepted Answer

Influenza-A

Answer

Influenza-C

Answer

Influenza-D

Answer

Influenza-B

Virology — MCQs

Virology — MCQs

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