gastroenteritis

Gastroenteritis is inflammation of the stomach and intestines that causes acute diarrhea, with or without vomiting, abdominal cramps, and fever. Most cases are infectious and self-limited. Viral infections are the most common cause worldwide, especially norovirus and rotavirus. Bacterial pathogens such as Salmonella, Campylobacter, Shiga toxin–producing Escherichia coli, and Shigella, as well as parasites like Giardia lamblia, can also cause illness. Transmission is usually fecal-oral via contaminated food or water, or through person-to-person contact.

Symptoms vary, but vomiting may precede or accompany diarrhea. Dehydration is a major concern, particularly in young children and older adults. Illness is typically 1–3 days for viral gastroenteritis and longer for bacterial infections; some cases may be more severe in immunocompromised individuals.

Diagnosis is usually clinical. Stool testing is reserved for severe, persistent, or febrile illness, dysentery, dehydration, or in at-risk patients. Tests may include stool culture, antigen assays, or multiplex PCR panels.

Management emphasizes rehydration and supportive care. Use oral rehydration solutions or IV fluids as needed; reintroduce normal feeding promptly. Zinc supplementation benefits children. Antiemetics may help symptoms. Avoid antidiarrheal drugs in young children or when invasive infection is suspected. Antibiotics are not routinely indicated and should be targeted to confirmed pathogens or severe disease.

Prognosis is generally favorable with proper fluid management. Complications include dehydration, electrolyte disturbances, and, rarely, invasive infections or postinfectious lactose intolerance. Prevention focuses on hand hygiene, safe food and water, sanitation, and vaccination where available, notably rotavirus vaccination.