Gastroenteritis (Stomach Flu & Food Poisoning): Causes & Treatment

Gastroenteritis is inflammation of the lining of the stomach and intestines, most often caused by an infection, and typically presenting with the combination of nausea, vomiting, diarrhoea, and abdominal cramping together — the feature that distinguishes it from diarrhoea alone. It's usually short-lived and manageable at home, but it's also genuinely common enough in India, and occasionally severe enough, to be worth understanding properly rather than dismissed as routine every time. At KAGE, gastroenteritis is managed with a clear focus on hydration and on recognizing the situations — a small minority — where more than supportive care is needed.

Acute gastroenteritis represents a substantial, ongoing public health burden in India: more than 13.9 million cases and 709 distinct outbreaks were reported in a single recent year, accounting for over a quarter of all disease outbreaks recorded nationally. Roughly a fifth of reported outbreaks are specifically foodborne, though the exact causative organism often goes unidentified due to limited timely laboratory testing at the point of illness. Contaminated drinking water is a well-documented, recurring source of outbreaks — including instances traced directly to sewage contamination of water supply systems — which is a useful thing to know both for prevention and for understanding why gastroenteritis clusters can occur among groups sharing the same food or water source.

• Viral — the most common cause in adults worldwide; norovirus is the leading cause of infectious gastroenteritis and foodborne outbreaks in adults, while rotavirus is more prominent in young children
• Bacterial — including E. coli, Salmonella, Shigella, and Campylobacter, typically from contaminated food or water; less commonly, cholera in specific outbreak settings
• Parasitic — including Giardia and Entamoeba histolytica (see the Diarrhoea page for more on amoebiasis specifically), more often associated with a longer or relapsing course than typical viral gastroenteritis

• Nausea and vomiting
• Watery diarrhoea
• Abdominal cramping
• Low-grade fever, in many cases
• Body aches and general fatigue
• Symptoms typically last a few days for viral causes, though some bacterial and parasitic causes can persist longer

Gastroenteritis is closely linked to travel, in both directions. Globally, more than half of travelers from developed countries to developing regions experience some form of travelers' diarrhoea, most often from unfamiliar local bacteria, viruses, or parasites in food and water. The same principle applies within India — someone traveling to Hyderabad from a different region, or from outside the country, can be exposed to organisms their gut isn't accustomed to, just as an Indian traveler abroad might be. This is relevant both for visitors to Hyderabad and for the patients KAGE sees who've traveled here from elsewhere in Telangana and Andhra Pradesh for other GI care.

• Usually a clinical diagnosis based on symptoms and history alone — most cases don't need testing
• Stool testing when symptoms are severe, bloody, persistent beyond the typical course, occurring during a known outbreak, or in someone who is immunocompromised
• Blood tests to assess hydration status and electrolyte balance in more significant cases

• Oral rehydration solution — the single most important treatment for the large majority of cases, more important than any medication
• Continued, gentle nutrition as tolerated, rather than prolonged fasting
• Anti-nausea medication, when vomiting is significant enough to prevent adequate fluid intake
• Targeted antibiotics only for specific confirmed or strongly suspected bacterial causes — not used routinely, and generally avoided for suspected viral gastroenteritis
• Antiparasitic treatment for confirmed parasitic causes

Most people recover fully within a few days without any lasting effect. But a meaningful proportion of people go on to develop IBS symptoms in the months following a gastroenteritis episode — a well-recognized pattern called post-infectious IBS (see the IBS page for more detail). If digestive symptoms such as bloating, altered bowel habits, or abdominal discomfort persist for weeks after the original infection has clearly resolved, it's worth mentioning to a gastroenterologist rather than assuming the gastroenteritis itself is simply 'lingering.'

• Drink water from a reliably safe source, and be cautious with ice and uncooked foods washed in tap water when unsure of the source
• Choose freshly prepared, thoroughly cooked food, particularly when eating outside familiar settings
• Practice regular handwashing, especially before eating and after using the restroom
• Be aware that shared food or water sources can cause clustered illness among groups — if several people who ate or drank the same thing become unwell together, that pattern itself is diagnostically useful information to share with a doctor

Most acute diarrhoea from gastroenteritis settles within a few days on fluids and oral rehydration, and needs no antibiotics at all. Our gastroenterologists get involved when it does not — dehydration that will not correct, blood in the stool, high fever, or symptoms carrying on past four weeks, at which point it is chronic diarrhoea being investigated rather than an infection being treated. If symptoms have outlasted the usual course, book a consultation.