Enteric infections — what they are and what to do right away

Sudden diarrhea, stomach cramps, nausea or vomiting after a meal or trip usually means an enteric infection — an infection of your gut caused by viruses, bacteria, or parasites. Common culprits are norovirus and rotavirus (viruses), E. coli, Salmonella, Shigella, Campylobacter (bacteria), and Giardia (a parasite). Symptoms can start hours to days after exposure and range from mild cramps to high fever and bloody stool.

Prevention & home care

Wash hands with soap and water for 20 seconds after using the bathroom and before eating. Hand sanitizer helps when soap isn’t available, but it’s not a full substitute for dirty hands. When traveling or eating street food, avoid raw salads, unpeeled fruit, unpasteurized dairy, and ice made from tap water. Drink bottled or boiled water in high-risk areas and thoroughly cook meats and seafood.

If you get sick, focus on preventing dehydration. Sip oral rehydration solutions (ORS) like WHO formula or Pedialyte; they replace salts and sugars lost in diarrhea. Start with small, frequent sips — try 50–100 ml every 10–20 minutes for infants, and 200–250 ml every 30 minutes for adults until vomiting eases. Keep eating normal foods as tolerated; bland, energy-containing food helps recovery more than prolonged fasting.

Over-the-counter loperamide (Imodium) can ease symptoms in adults without fever or bloody stool, but avoid it if you have high fever, bloody diarrhea, or suspected certain infections. Probiotics may shorten symptoms for some viral or antibiotic-related diarrhea, but they are an adjunct, not a replacement for rehydration.

When to see a doctor and treatment basics

Seek medical care if you have: high fever (>38.5°C/101.5°F), persistent vomiting that prevents fluids, signs of dehydration (dizziness, low urine, dry mouth), bloody or black stools, severe belly pain, diarrhea lasting more than 48–72 hours, or if you’re very young, elderly, pregnant, or immunocompromised. For these cases, your doctor may order stool tests — culture, parasite ova and cysts, or modern PCR panels — to identify the pathogen.

Treatment depends on the cause. Most viral infections get better with fluids and time. Bacterial infections sometimes need antibiotics: azithromycin is often used for traveler’s diarrhea in areas with fluoroquinolone resistance; ciprofloxacin may still be used in some regions. Giardia is treated with metronidazole or tinidazole. C. difficile requires specific therapy like oral vancomycin or fidaxomicin. Never start antibiotics without medical advice — they can make some infections worse or promote resistance.

Finally, vaccines help prevent some enteric illnesses: rotavirus vaccines for infants and typhoid vaccines for travelers to high-risk countries. If you travel soon, talk to a clinician about vaccines and destination-specific advice.

Quick checklist: hydrate first, wash hands, avoid risky foods/drinks, use ORS, and see a clinician for severe signs or if symptoms don’t improve in a couple of days.