What is the most frequent cause of viral diarrhea in adults?

Appeared in: AIIMS Delhi NO - 2017

Explanation

Norovirus, a type of Calicivirus, is the most common cause of gastroenteritis outbreaks and sporadic cases of viral diarrhea in adults.
It is highly infectious and spreads easily through the fecal-oral route, contaminated food or water, and person-to-person contact.
Norovirus is well-known for causing large, explosive outbreaks in community settings such as schools, hospitals, nursing homes, and cruise ships.

Option A: While a major cause of viral diarrhea, Rotavirus primarily affects infants and young children. Adults are less commonly affected, and infections are often asymptomatic.
Option B: Enteric adenovirus serotypes 40 and 41 are a common cause of diarrhea, but almost exclusively in children younger than two years of age.
Option D: Astrovirus is a recognized cause of gastroenteritis, particularly in young children, but it is considered an uncommon pathogen in the adult population.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Etiology of viral gastroenteritis in adults as background academic context rather than a clinical decision trigger.
For nurses, identifying a potential Norovirus outbreak in a healthcare facility is critical for implementing immediate and strict infection control protocols, including contact precautions, enhanced hand hygiene (soap and water are more effective than alcohol-based sanitizers), and environmental disinfection to prevent widespread transmission.
Patient education should focus on hydration, handwashing, and preventing spread at home, especially since the illness is self-limiting but highly contagious.
What if? If the question specified the patient was a 9-month-old infant, the most likely answer would change to Rotavirus, which is the leading cause of severe dehydrating diarrhea in that age group.

How to Approach the Question

First, identify the key demographic specified in the question stem, which is 'adults'.
Next, identify the clinical condition, which is 'viral diarrhea'.
The question asks for the 'most frequent' cause, which requires knowledge of the epidemiology of infectious diseases.
Mentally review the common viral agents of gastroenteritis and their primary target populations.
Compare the options based on this knowledge: Rotavirus (children), Adenovirus (children), Norovirus (adults and older children), and Astrovirus (children).
Select Norovirus as it is the leading cause of viral diarrhea in the adult population.

Concept Tested & Keywords

Concept Tested: Etiology of viral gastroenteritis in adults
Stem keywords: viral diarrhea, adults, most frequent cause
Lead-in keywords: What is
Clinical cues: The patient demographic 'adults' is the key to differentiating between the options.

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 2056-2058, 2057-2059

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