Virology Practice Questions

Q: Patient with fever, photophobia, neck stiffness. CSF shows lymphocytic pleocytosis. Most likely virus?

Enterovirus. ***Enterovirus*** - **Enteroviruses** are the most common cause of **aseptic meningitis**, characterized by fever, photophobia, neck stiffness [2], and **lymphocytic pleocytosis** in the CSF. - They are transmitted via the **fecal-oral route** and are more prevalent in summer and fall [1]. *West Nile virus* - While West Nile virus can cause meningoencephalitis with lymphocytic pleocytosis, it is typically associated with **seasonal epidemics** and often presents with more severe neurological symptoms like **flaccid paralysis** or **encephalitis**. - Without specific exposure history or geographical context, it's a less common default answer for general aseptic meningitis. *HSV* - **Herpes simplex virus (HSV)** can cause meningitis or encephalitis, but HSV-1 often leads to severe focal encephalitis with specific neurological deficits [3] and may show **red blood cells** in the CSF. - HSV-2 is a common cause of recurrent aseptic meningitis (Mollaret's meningitis) but usually presents with **genital lesions**. *Mumps virus* - Prior to widespread vaccination, **mumps virus** was a significant cause of aseptic meningitis and orchitis. - However, in vaccinated populations, mumps meningitis is rare, and the presentation would typically include **parotitis** (swollen salivary glands), which is not mentioned here.

Q: SD plasma destroys lipid-enveloped viruses. On SD plasma transfusion, which of the following infections is the likely possibility?

HAV. ***HAV*** - **Single-stranded non-enveloped RNA virus** of the Picornaviridae family, which means it lacks a **lipid envelope**. - As SD plasma therapy **destroys lipid-enveloped viruses,** HAV would likely persist and cause infection. *HBV* - **HBV** (Hepatitis B Virus) is a **lipid-enveloped DNA virus**. - SD plasma processing effectively **inactivates enveloped viruses** like HBV, making transfusion-associated infection unlikely. *HCV* - **HCV** (Hepatitis C Virus) is a **lipid-enveloped RNA virus**. - Like other enveloped viruses, HCV would be **inactivated by SD plasma processing**, thus reducing the risk of transmission. *HIV* - **HIV** (Human Immunodeficiency Virus) is a **lipid-enveloped RNA virus**. - **SD plasma treatment** is highly effective in inactivating HIV due to its **lipid envelope**, making transmission unlikely through this product.

Q: Mother had painful vesicular lesions over genitalia one year back. Now Baby is born with features of meningitis and fever and rashes in abdomen and forearm and died within a week. Scrapings from lesions showed multinucleated giant cells. What is the most likely organism?

A. HSV2. ***HSV2*** - The mother's history of **genital vesicular lesions** and the infant's presentation with **meningitis**, **fever**, **rashes**, and rapid death are highly characteristic of **neonatal herpes simplex virus (HSV) infection**, typically caused by **HSV-2**. - **Multinucleated giant cells** on lesion scrapings (Tzanck smear) are a classic finding in HSV infections, indicating a herpesvirus etiology. - Neonatal HSV is typically acquired during **vaginal delivery** through an infected birth canal and presents with disseminated disease in the first week of life. *Enterovirus 70* - **Enterovirus 70** is primarily associated with **acute hemorrhagic conjunctivitis** and occasionally neurological complications, not neonatal meningitis with disseminated vesicular rash. - It does not cause **vesicular lesions** or lead to multinucleated giant cells on microscopic examination. *CMV* - **Cytomegalovirus (CMV)** can cause congenital infection with CNS involvement and rash, but typically presents with **intrauterine growth restriction**, **hepatosplenomegaly**, **hearing loss**, and **intracranial calcifications**. - The maternal history of **recurrent genital vesicular lesions** and **acute neonatal presentation** with multinucleated giant cells on Tzanck smear are not characteristic of CMV. - CMV causes **owl's eye inclusions** on histopathology, not multinucleated giant cells. *VZV* - **Varicella-zoster virus (VZV)** causes **chickenpox** and **shingles**, and while it can cause congenital or neonatal varicella with multinucleated giant cells, the maternal history of **recurrent genital vesicular lesions** points specifically to HSV-2. - Neonatal VZV typically occurs when the mother has **primary varicella infection** near delivery, not a history of genital lesions one year prior.

Q: Which organism is most associated with neonatal meningitis and skin rash?

HSV-2. ***HSV-2*** - **Neonatal herpes simplex virus (HSV)** infection, often caused by HSV-2 acquired during vaginal delivery, can manifest with **meningitis** and characteristic **skin vesicles** or a rash. - The rash typically presents as clustered **vesicles on an erythematous base** and can be widespread, making it a key diagnostic clue alongside neurological symptoms. *VZV* - **Varicella-zoster virus (VZV)** can cause neonatal varicella, which presents with a rash but **meningitis** is a much less common complication, typically associated with more severe disseminated disease. - The rash of neonatal varicella usually appears as **macules, papules, vesicles, and scabs** in various stages of healing, rather than the clustered vesicles seen in HSV. *Group B Streptococcus (GBS)* - **GBS** is a leading cause of **neonatal meningitis** and sepsis, but it typically does **not cause a skin rash** in affected infants. - While GBS can cause systemic signs of infection and neurological symptoms, cutaneous manifestations are not characteristic. *Enterovirus 71* - **Enterovirus 71** is known to cause hand, foot, and mouth disease, which includes a **rash** and can, in severe cases, cause **meningitis** or encephalitis. - However, the rash is typically maculopapular or vesicular on the palms, soles, and buttocks, and this association is less common for neonatal meningitis with widespread skin findings compared to HSV.

Q: Which of the following is not a mode of transmission for Hepatitis B?

Transmitted by respiratory droplets. ***Transmitted by respiratory droplets*** - Hepatitis B virus (HBV) is primarily transmitted through bodily fluids, not through the air via **respiratory droplets** like cold or flu viruses. - This means casual contact, coughing, or sneezing does **not** spread HBV. *Transmission occurs via sexual contact* - HBV is highly concentrated in bodily fluids like **blood, semen, and vaginal secretions**, making sexual intercourse a common mode of transmission. - Unprotected sexual contact with an infected partner significantly increases the risk of acquiring HBV. *Can be transmitted from mother to child* - **Perinatal transmission** from an infected mother to her baby during birth is a significant route of HBV transmission, especially in endemic areas. - This can lead to chronic infection in infants if not prevented with vaccination and hepatitis B immunoglobulin. *Transmission occurs via blood* - HBV is readily transmitted through contact with infected blood, such as via **sharing needles** among intravenous drug users or through **blood transfusions** in settings where screening is inadequate. - Accidental **needle sticks** in healthcare settings are also a risk factor for HBV transmission.

Q: A 4-year-old child with barking cough is diagnosed with croup. Which virus is most likely responsible?

Parainfluenza virus. ***Parainfluenza virus*** - **Parainfluenza viruses (PIV)** are the most common cause of **croup**, characterized by a **barking cough**, hoarseness, and inspiratory stridor. - PIV types 1 and 2 are particularly associated with acute laryngotracheobronchitis (croup) in young children. *Rhinovirus* - **Rhinoviruses** are the primary cause of the **common cold** and typically result in upper respiratory tract symptoms like runny nose, sneezing, and sore throat. - They are generally not associated with the severe laryngeal inflammation that causes the characteristic barking cough of croup. *Adenovirus* - **Adenoviruses** can cause a variety of respiratory illnesses, including pharyngitis and pneumonia, and sometimes mimic croup. - However, they are a less frequent cause of croup compared to parainfluenza viruses. *Respiratory syncytial virus* - **Respiratory syncytial virus (RSV)** is the leading cause of **bronchiolitis** and pneumonia in infants and young children. - While RSV can cause upper respiratory symptoms, it typically leads to wheezing and crackles rather than the barking cough of croup.

Q: Which of the following pathogens is most commonly associated with acute infectious diarrhea?

Rotavirus. ***Rotavirus*** - **Rotavirus** is the leading cause of **severe, acute diarrheal disease** in **infants and young children worldwide**, especially in unvaccinated populations. - It causes significant **morbidity and mortality** globally, primarily through dehydration. *Salmonella* - While *Salmonella* can cause acute infectious diarrhea, particularly **foodborne outbreaks**, it is **less common overall** than rotavirus, especially in children. - It often presents with **fever, abdominal cramps**, and **bloody or non-bloody diarrhea**, and can lead to systemic infections. *Escherichia coli* - Various strains of *E. coli* can cause diarrhea (e.g., **ETEC, EPEC, EHEC**), but collectively they do not surpass rotavirus as the single most common cause of acute infectious diarrhea globally. - **Enterohemorrhagic *E. coli* (EHEC)**, particularly O157:H7, is known for causing **hemorrhagic colitis** and **hemolytic uremic syndrome**. *Shigella* - *Shigella* species cause **bacillary dysentery**, characterized by **bloody diarrhea, fever, and severe abdominal cramps**. - While it is a significant cause of diarrheal disease, its prevalence is generally **lower than rotavirus**, especially in developed countries.

Q: A patient presents with fever, sore throat, and splenomegaly. A blood smear shows atypical lymphocytes, and a Monospot test is positive. What is the likely etiological agent?

Epstein-Barr virus. ***Epstein-Barr virus*** - The combination of **fever**, **sore throat**, **splenomegaly**, **atypical lymphocytes** on a blood smear, and a **positive Monospot test** is classic for **infectious mononucleosis**, which is caused by the Epstein-Barr virus (EBV). - EBV primarily infects **B lymphocytes** and epithelial cells, leading to a robust cytotoxic T-cell response responsible for the atypical lymphocytes. *Cytomegalovirus* - CMV can cause a **mononucleosis-like syndrome** with fever and atypical lymphocytes, but it typically results in a **negative Monospot test**. - While CMV can cause **splenomegaly**, the specific constellation of symptoms with a positive Monospot points away from CMV. *Hepatitis B virus* - **Hepatitis B virus (HBV)** primarily causes **liver inflammation** (hepatitis), which can manifest with jaundice, fatigue, and abdominal pain. - HBV does not typically cause the triad of **splenomegaly, sore throat, and atypical lymphocytes** characteristic of mononucleosis, nor does it result in a positive Monospot test. *Toxoplasma gondii* - *Toxoplasma gondii* can cause **lymphadenopathy** and a **mononucleosis-like illness** in immunocompetent individuals. - However, **splenomegaly** is less common, and it is not associated with a **positive Monospot test**.

Q: A 45-year-old woman presents with jaundice and elevated liver enzymes. A serological test is positive for HBsAg and anti-HBc IgM. What is the stage of her hepatitis B infection?

Acute. ***Acute*** - The presence of **HBsAg** (hepatitis B surface antigen) indicates active infection, while **anti-HBc IgM** (antibody to hepatitis B core antigen, IgM class) specifically points to a recent, **acute infection** [1]. - Elevated liver enzymes and jaundice further support a recent, **active inflammatory process** in the liver. *Chronic* - Chronic hepatitis B is characterized by the presence of **HBsAg for more than 6 months**, often with **anti-HBc IgG** rather than IgM [1]. - The presence of **anti-HBc IgM** rules out a purely chronic infection, as it signifies recent exposure. *Resolved* - A resolved infection typically shows **negative HBsAg** and **positive anti-HBs** (antibody to hepatitis B surface antigen), indicating immunity [1]. - The presence of **HBsAg** means the infection is still active, not resolved. *Carrier* - The term "carrier" refers to a person with chronic hepatitis B infection (HBsAg positive for >6 months), often with relatively stable liver enzymes and minimal liver damage, but can also refer to chronic active hepatitis. - The presence of **anti-HBc IgM** indicates an **acute phase**, not a stable carrier state without acute viral replication.

Question 1

Patient with fever, photophobia, neck stiffness. CSF shows lymphocytic pleocytosis. Most likely virus?

Accepted Answer

Enterovirus

Answer

West Nile virus

Answer

HSV

Answer

Mumps virus

Question 2

SD plasma destroys lipid-enveloped viruses. On SD plasma transfusion, which of the following infections is the likely possibility?

Accepted Answer

HAV

Answer

HBV

Answer

HCV

Answer

HIV

Question 3

Mother had painful vesicular lesions over genitalia one year back. Now Baby is born with features of meningitis and fever and rashes in abdomen and forearm and died within a week. Scrapings from lesions showed multinucleated giant cells. What is the most likely organism?

Accepted Answer

A. HSV2

Answer

B. Enterovirus 70

Answer

C. CMV

Answer

D. VZV

Question 4

Which organism is most associated with neonatal meningitis and skin rash?

Accepted Answer

HSV-2

Answer

VZV

Answer

Group B Streptococcus (GBS)

Answer

Enterovirus 71

Question 5

Which of the following is not a mode of transmission for Hepatitis B?

Accepted Answer

Transmitted by respiratory droplets

Answer

Transmission occurs via sexual contact

Answer

Can be transmitted from mother to child

Answer

Transmission occurs via blood

Question 6

Which of the following mechanisms is characteristic of HIV as a retrovirus after it enters the host cell?

Accepted Answer

It uses reverse transcriptase after entry to convert RNA to DNA.

Answer

It integrates into the host genome after entry.

Answer

It binds to CD4 via gp120.

Answer

It uses CCR5 co-receptor for entry into host cells.

Question 7

A 4-year-old child with barking cough is diagnosed with croup. Which virus is most likely responsible?

Accepted Answer

Parainfluenza virus

Answer

Rhinovirus

Answer

Adenovirus

Answer

Respiratory syncytial virus

Question 8

Which of the following pathogens is most commonly associated with acute infectious diarrhea?

Accepted Answer

Rotavirus

Answer

Salmonella

Answer

Escherichia coli

Answer

Shigella

Question 9

A patient presents with fever, sore throat, and splenomegaly. A blood smear shows atypical lymphocytes, and a Monospot test is positive. What is the likely etiological agent?

Accepted Answer

Epstein-Barr virus

Answer

Cytomegalovirus

Answer

Hepatitis B virus

Answer

Toxoplasma gondii

Question 10

A 45-year-old woman presents with jaundice and elevated liver enzymes. A serological test is positive for HBsAg and anti-HBc IgM. What is the stage of her hepatitis B infection?

Accepted Answer

Acute

Answer

Chronic

Answer

Resolved

Answer

Carrier

Virology — MCQs

Virology — MCQs

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