**Question:** An adolescent male developed vomiting and diarrhoea 1 hour after having food from a restaurant. The most likely pathogen is

A. Salmonella
B. Escherichia coli (E. coli)
C. Vibrio cholerae
D. Rotavirus

**Correct Answer:** D. Rotavirus

**Core Concept:** Rotavirus is a common cause of acute gastroenteritis, a condition characterized by inflammation of the lining of the gastrointestinal tract resulting in vomiting, diarrhea, and sometimes dehydration. Rotavirus is a positive-sense, single-stranded RNA virus belonging to the Reoviridae family.

**Why the Correct Answer is Right:** In this scenario, the patient experienced symptoms of vomiting and diarrhoea within an hour after consuming food from a restaurant, indicating a possible foodborne infection. Among the provided options, Rotavirus is the most likely pathogen to cause this acute onset of gastroenteritis. Rotavirus is typically transmitted through contaminated food or water, and its replication and shedding in the gastrointestinal tract lead to the symptoms observed.

**Why Each Wrong Option is Incorrect:**

A. Salmonella: Although Salmonella can cause gastroenteritis, its incubation period is typically longer (1-3 days) and the symptoms may involve fever, abdominal pain, and bloody diarrhoea, which are not mentioned in the question.
B. Escherichia coli (E. coli): E. coli can cause gastroenteritis, but the rapid onset (within an hour) is uncommon and the symptoms may vary, making it less likely than Rotavirus.
C. Vibrio cholerae: Vibrio cholerae is responsible for cholera, a different clinical entity characterized by severe watery diarrhoea and hypovolaemic shock, which is not consistent with the presented symptoms.

**Core Concept:** Rotavirus is the primary cause of diarrheal diseases in children worldwide, particularly in resource-limited settings. It is responsible for approximately 20% of all childhood diarrhoeal diseases.

**Clinical Pearls:**

1. Rotavirus infection is a common cause of acute gastroenteritis in children, with symptoms typically including watery diarrhoea, vomiting, and fever.
2. The incubation period for Rotavirus infection is typically 1-14 days, with an average of 2-3 days.
3. Diagnosis of Rotavirus infection is often clinical, but stool testing can confirm the presence of the virus.
4. Rotavirus infection is preventable through vaccination, particularly in high-risk populations.
5. Treatment focuses on supportive care, including rehydration and electrolyte replacement, as there is no specific antiviral therapy for Rotavirus infection.