Enteroviruses and Rhinoviruses — MCQs
A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?
Which of the following diseases has the largest submerged portion in the iceberg model of disease?
Which vaccine is contraindicated in a 6-month-old infant whose sibling is on chemotherapy for leukemia?
An ICU patient is suffering from Rhinovirus infection. How do we treat the patient?
Most common type of pathogenic bacteria grow at temperatures of
Coxsackie virus is classified as which type of virus?
Most common presentation of adult rhinosporidiosis is?
Hand-foot-mouth disease is caused by:
Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?
A patient presented with meningitis, and the CSF sample shows Gram-negative diplococci on Gram staining and microscopy. Which of the following features/tests will be characteristic of the organism?
Enteroviruses and Rhinoviruses Indian Medical PG Practice Questions and MCQs
Question 1: A child presented with bluish-white spots in the mouth followed by a rash. What is the genome of the most likely causative agent?
- A. Enveloped virus with single-stranded RNA (Correct Answer)
- B. Double stranded Naked RNA
- C. Naked virus with single-stranded RNA
- D. Double stranded Enveloped RNA
Explanation: ***Enveloped virus with single-stranded RNA*** - Bluish-white spots in the mouth (**Koplik spots**) followed by a rash are pathognomonic for **measles**, which is caused by the **measles virus**. - The measles virus is a **paramyxovirus**, characterized as an **enveloped, negative-sense, single-stranded RNA virus**. *Double stranded Naked RNA* - No major human pathogen belongs to this specific genomic and structural classification. - Most **dsRNA viruses** like **rotavirus** are **naked** but cause gastroenteritis, not measles. *Naked virus with single-stranded RNA* - Viruses like **rhinovirus** (common cold) or **poliovirus** fit this description but do not cause Koplik spots or measles. - **Naked viruses** lack a lipid envelope, making them generally more resistant to environmental factors. *Double stranded Enveloped RNA* - There are no known medically significant human viruses that are both **enveloped** and contain **double-stranded RNA**. - Viral genomes are typically either DNA or RNA, and RNA viruses are usually single-stranded (positive or negative sense) or double-stranded, with or without an envelope.
Question 2: Which of the following diseases has the largest submerged portion in the iceberg model of disease?
- A. Influenza (Correct Answer)
- B. Chickenpox
- C. Tetanus
- D. Rabies
Explanation: **The Iceberg Model of Disease** represents the concept that for many diseases, only a small portion of cases (the "tip" above water) are clinically apparent and reported, while a much larger portion (the "submerged" part) consists of asymptomatic, subclinical, or undiagnosed cases. ***Influenza*** - Has the **largest submerged portion** among the given options, with **50-75% of infections being asymptomatic or mild** and going undiagnosed - High transmissibility and varied clinical presentation contribute to significant hidden burden - Only severe cases requiring hospitalization typically get reported, representing just the "tip of the iceberg" - Classic example of diseases with large subclinical-to-clinical ratio *Chickenpox* - Most cases are **clinically apparent** with characteristic vesicular rash - Asymptomatic infections are rare due to distinctive clinical features - High visibility of cases reduces the submerged portion significantly *Tetanus* - **Severe, acute neurological condition** with distinct clinical manifestations (trismus, risus sardonicus, opisthotonus) - Almost all cases are diagnosed due to dramatic presentation - Virtually no submerged portion - what exists clinically is recognized *Rabies* - **Nearly uniformly fatal** once symptoms appear, making all symptomatic cases clinically evident - No asymptomatic or mild phase after symptom onset - Minimal to no submerged portion in the iceberg model
Question 3: Which vaccine is contraindicated in a 6-month-old infant whose sibling is on chemotherapy for leukemia?
- A. Oral polio vaccine (Correct Answer)
- B. Hepatitis B
- C. Rotavirus vaccine
- D. DPT
Explanation: ***Oral polio vaccine*** - The **oral polio vaccine (OPV)** is a live attenuated vaccine containing weakened but live viruses. - It is **absolutely contraindicated** in individuals with immunocompromised household contacts (like a sibling on **chemotherapy**) due to the risk of **vaccine-associated paralytic poliomyelitis (VAPP)** from shedding of the live vaccine virus. - The shed virus can be transmitted to and cause disease in immunocompromised contacts. - This is the primary reason most countries have switched to **inactivated polio vaccine (IPV)**. *Hepatitis B* - The **Hepatitis B vaccine** is an inactivated (non-live) recombinant vaccine. - It poses no risk of transmitting live virus to an immunocompromised individual. - It is safe to administer to an infant with an immunocompromised household contact. *Rotavirus vaccine* - The **Rotavirus vaccine** is also a live attenuated vaccine, and there is a **relative contraindication** when household contacts are severely immunocompromised. - The vaccine virus can be shed in stool for several days after vaccination. - However, compared to OPV, the risk of serious disease transmission is considered much lower, and some guidelines allow its use with precautions (strict hand hygiene, avoiding diaper changes by immunocompromised contacts). - In the context of this question, **OPV has a stronger absolute contraindication** than rotavirus vaccine. *DPT* - The **DPT vaccine** (Diphtheria, Pertussis, Tetanus) is an **inactivated vaccine** containing toxoids and killed bacterial components. - It is safe to administer to an infant with an immunocompromised household contact as there is no risk of shedding live pathogens.
Question 4: An ICU patient is suffering from Rhinovirus infection. How do we treat the patient?
- A. Piperacillin + Tazobactam + Azithromycin
- B. Clarithromycin
- C. Cephalosporin + Ganciclovir
- D. Supportive care only (Correct Answer)
Explanation: ***Supportive care only*** - **Rhinovirus** is a common cause of the **common cold**, and there is no specific antiviral treatment available for it. [1] - Management focuses on alleviating symptoms such as fever, congestion, and cough to ensure patient comfort and prevent secondary complications, especially in an ICU setting. *Piperacillin + Tazobactam + Azithromycin* - This combination is a broad-spectrum antibiotic regimen (piperacillin/tazobactam is an extended-spectrum penicillin, and azithromycin is a macrolide) targeting bacterial infections. [2] - **Rhinovirus is a virus**, and antibiotics are ineffective against viral infections, making this an inappropriate treatment. *Clarithromycin* - **Clarithromycin** is a macrolide antibiotic primarily used to treat bacterial infections, such as respiratory tract infections caused by **atypical bacteria** or community-acquired pneumonia. [2] - It has no activity against **Rhinovirus**, a common cold virus. *Cephalosporin + Ganciclovir* - **Cephalosporins** are a class of beta-lactam antibiotics used for various bacterial infections. [2] - **Ganciclovir** is an antiviral agent specifically used to treat **cytomegalovirus (CMV)** infections, not Rhinovirus.
Question 5: Most common type of pathogenic bacteria grow at temperatures of
- A. 0 to 20 degrees
- B. -20 degrees
- C. Above 50 degrees
- D. 25 to 40 degrees centigrade (Correct Answer)
Explanation: ***25 to 40 degrees centigrade*** - Most **pathogenic bacteria** are **mesophiles**, meaning they thrive in moderate temperatures, typically within the range of **25°C to 40°C**. - This temperature range is optimal for their metabolic activity and rapid reproduction, aligning with the **human body temperature** of 37°C, which is why they cause infections. *0 to 20 degrees* - This temperature range is characteristic of **psychrotrophic** bacteria, which can grow at refrigerator temperatures but are not typically the most common human pathogens. - While some psychrotrophs can cause disease (e.g., *Listeria monocytogenes*), the majority of common human bacterial pathogens prefer warmer temperatures. *-20 degrees* - This extremely low temperature is usually used for **long-term storage** of bacteria to inhibit their growth and preserve them, often for laboratory purposes. - Most bacteria would be **dormant or killed** at this temperature, making it unsuitable for active growth. *Above 50 degrees* - Temperatures above 50°C are characteristic of **thermophilic** bacteria, which are adapted to very hot environments like hot springs. - These bacteria are generally **not pathogenic** to humans, as human body temperature is too low for their optimal growth.
Question 6: Coxsackie virus is classified as which type of virus?
- A. Pox virus
- B. Enterovirus (Correct Answer)
- C. Myxovirus
- D. Herpes virus
Explanation: ***Enterovirus*** - **Coxsackie virus** belongs to the genus *Enterovirus* within the family *Picornaviridae*. - Enteroviruses are characterized as **non-enveloped, positive-sense, single-stranded RNA viruses** and typically infect the gastrointestinal tract. *Herpes virus* - Herpes viruses are **enveloped, double-stranded DNA viruses** known for causing latent infections. - Examples include HSV-1 (oral herpes) and VZV (chickenpox), which are distinct from Coxsackie. *Pox virus* - Pox viruses are **large, enveloped, double-stranded DNA viruses** that replicate in the cytoplasm of infected cells. - Smallpox and molluscum contagiosum are caused by pox viruses, which have different genetic and structural characteristics than Coxsackie virus. *Myxovirus* - **Myxovirus** is an older classification that once included viruses now categorized into *Orthomyxoviridae* (e.g., influenza) and *Paramyxoviridae* (e.g., measles, mumps). - These are **enveloped, negative-sense, single-stranded RNA viruses**, a different viral structure and replication strategy compared to Coxsackie virus.
Question 7: Most common presentation of adult rhinosporidiosis is?
- A. Halitosis
- B. Pain
- C. Anosmia
- D. Polypoidal mass (Correct Answer)
Explanation: ***Polypoidal mass*** - The most common presentation of adult rhinosporidiosis is a **friable, reddish, polypoidal or sessile mass** in the nasal cavity. - These masses are often described as having a **strawberry-like appearance** due to multiple white dots, which are sporangia. *Halitosis* - While rhinosporidiosis can cause symptoms like **nasal obstruction** and discharge, **fetid breath (halitosis)** is not typically the primary or most common presentation. - Halitosis is more commonly associated with other dental or systemic issues, or with severe secondary infections. *Pain* - **Pain is rare** in rhinosporidiosis unless there is significant secondary infection or involvement of adjacent structures. - The lesions are generally asymptomatic until they cause mechanical obstruction or bleeding. *Anosmia* - **Anosmia (loss of smell)** can occur due to mechanical obstruction of the nasal passages by the polypoidal mass. - However, it is a **secondary symptom** resulting from the mass effect, not the most common initial or direct presentation of the disease itself.
Question 8: Hand-foot-mouth disease is caused by:
- A. Coxsackie-B virus
- B. EBV
- C. CMV
- D. Coxsackie-A virus (Correct Answer)
Explanation: ***Coxsackie-A virus*** - Hand-foot-mouth disease (HFMD) is most commonly caused by **Coxsackievirus A16** within the species **Human enterovirus A**. - Other **Coxsackievirus A serotypes** can also cause HFMD, particularly **A6, A10**, and **Enterovirus A71**. *Coxsackie-B virus* - **Coxsackievirus B** is known to cause a range of illnesses, including **myocarditis**, **pleurodynia (Bornholm disease)**, and **pericarditis**. - While it belongs to the same genus (Enterovirus), it is not the typical causative agent of HFMD. *EBV* - **Epstein-Barr Virus (EBV)** is a herpesvirus that causes **infectious mononucleosis**, **Burkitt's lymphoma**, and **nasopharyngeal carcinoma**. - It is transmitted through saliva and is **not associated with HFMD**. *CMV* - **Cytomegalovirus (CMV)** is a common virus that can cause a wide spectrum of diseases, especially in immunocompromised individuals and congenitally. - It is known for causing mononucleosis-like syndrome, congenital infections, and retinitis, but it is **not associated with HFMD**.
Question 9: Acute Hemorrhagic Conjunctivitis is primarily caused by which type of Enterovirus?
- A. Enterovirus type 68
- B. Enterovirus type 69
- C. Enterovirus type 70 (Correct Answer)
- D. Enterovirus type 71
Explanation: ***Enterovirus type 70*** - **Enterovirus type 70** is the most common cause of **Acute Hemorrhagic Conjunctivitis (AHC)**, particularly in epidemic outbreaks. - AHC presents with rapid onset of **ocular pain**, **redness**, **swelling**, and **subconjunctival hemorrhages**. *Enterovirus type 68* - **Enterovirus D68 (EV-D68)** is primarily known for causing **respiratory illnesses**, ranging from mild to severe, and is associated with acute flaccid myelitis. - While it can cause respiratory symptoms, it is not a primary cause of **Acute Hemorrhagic Conjunctivitis**. *Enterovirus type 69* - **Enterovirus type 69** is a rare serotype and is not typically associated with specific human diseases or large-scale outbreaks. - Unlike EV70, it is not recognized as a significant cause of **conjunctivitis**. *Enterovirus type 71* - **Enterovirus A71 (EV-A71)** is a common cause of **hand, foot, and mouth disease (HFMD)**, especially in children, and can also lead to severe neurological complications. - While it causes various infections, it is not the primary cause of **hemorrhagic conjunctivitis**.
Question 10: A patient presented with meningitis, and the CSF sample shows Gram-negative diplococci on Gram staining and microscopy. Which of the following features/tests will be characteristic of the organism?
- A. Oxidase positive, catalase positive, ferments glucose and maltose (Correct Answer)
- B. Catalase negative, optochin sensitive, alpha-hemolytic
- C. Oxidase negative, catalase positive, coagulase positive
- D. Catalase positive, urease positive, does not ferment glucose
Explanation: ***Oxidase positive, catalase positive, ferments glucose and maltose*** - The CSF findings show **Gram-negative diplococci**, characteristic of *Neisseria meningitidis*, a major cause of bacterial meningitis. - *N. meningitidis* is definitively identified by being **oxidase positive, catalase positive**, and able to **ferment both glucose and maltose**. *Catalase negative, optochin sensitive, alpha-hemolytic* - These are characteristic features of *Streptococcus pneumoniae*, which appears as **Gram-positive lancet-shaped diplococci**, not the Gram-negative diplococci seen in this case. - *S. pneumoniae* is **catalase negative** and shows **alpha-hemolysis** on blood agar, distinguishing it from Neisseria species. *Oxidase negative, catalase positive, coagulase positive* - These biochemical properties describe *Staphylococcus aureus*, which appears as **Gram-positive cocci in clusters** on microscopy. - *S. aureus* is **oxidase negative** and **coagulase positive**, completely different from the organism characteristics shown in the CSF sample. *Catalase positive, urease positive, does not ferment glucose* - This combination suggests organisms like **Enterobacteriaceae** or *Cryptococcus neoformans*, which have different morphological appearances. - The **urease positivity** and **lack of glucose fermentation** are inconsistent with *N. meningitidis*, which readily ferments glucose.
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