Gastroenteritis, often called the stomach flu, is an infection or inflammation of the digestive tract (stomach and intestines) typically caused by viruses, but it can also be due to bacteria or parasites. It’s usually contagious and spreads through contaminated food, water, surfaces, or close contact with an infected person. The core causes and transmission routes are summarized below, followed by practical guidance. Core causes

• Viral origins: Norovirus and rotavirus are among the most common viral causes; viruses are highly contagious and can shed in stool and vomit for days to weeks. Transmission often occurs via hands, surfaces, or ingestion of contaminated food or water. [Norovirus, rotavirus](javascript:void(0)) [viruses](javascript:void(0))

• Bacterial origins: Foodborne bacteria such as Campylobacter, Salmonella, and Escherichia coli can cause gastroenteritis, typically after eating undercooked or contaminated foods or drinking contaminated water.

• Parasitic origins: Parasites like Giardia and Cryptosporidium can cause gastroenteritis, often through contaminated water or poor food handling.

How it spreads

• Direct person-to-person contact, especially if hands are not washed after using the toilet or changing diapers.

• Contaminated food or water, including undercooked meats, unpasteurized dairy, and produce washed with contaminated water.

• Contact with contaminated surfaces or objects, then touching the mouth or face.

Typical symptoms

• Diarrhea, vomiting, stomach cramps or pain, nausea, sometimes fever or headache. Symptoms usually appear within hours to a couple of days after exposure.

Prevention and quick relief

• Prevention: Hand hygiene with soap and water, careful food handling (proper cooking, avoiding cross-contamination), drinking clean water or treated beverages, and staying home when sick to avoid spreading illness. Vaccination exists for certain viruses (e.g., rotavirus in children, depending on region).

• Hydration: Oral rehydration solutions or clear fluids help prevent dehydration, especially in children and older adults. If vomiting prevents drinking, take small sips frequently; seek medical care if dehydration signs appear.

• When to seek care: Severe dehydration, bloody stools, high fever, pregnancy-related concerns, or symptoms persisting beyond a few days warrant medical evaluation. Infants, young children, older adults, and people with weakened immune systems are at higher risk and may need prompt care.

Treatment overview

• Most cases are self-limiting and resolve in a few days with rest and fluids. Antibiotics are not useful for viral gastroenteritis and are used only for certain bacterial infections under medical guidance. Antiparasitic medications may be indicated for specific parasitic infections.

• In some cases, doctors may recommend antiemetics for severe vomiting or rehydration therapy for significant dehydration.

Key takeaways

• Gastroenteritis is most commonly viral and highly contagious; good hygiene and safe food/hydration practices are central to prevention and management.

• Monitor for dehydration and seek medical care if warning signs appear or if at-risk individuals are affected.

If you’d like, I can tailor this to a specific context (e.g., children, travel, or workplace) or provide a quick at-a-glance checklist for home care and when to seek help.