Indore contaminated water outbreak: How soon do symptoms appear after drinking?

Drinking contaminated drinking water can cause symptoms within hours in some people but in others it may take several days to even a few weeks, depending on the organism and the dose ingested. Most patients present with acute gastroenteritis-like illness, and early recognition plus prompt rehydration and appropriate antimicrobials can significantly reduce complications and deaths.

The incubation period varies by pathogen and by how heavily the water is contaminated. Broadly, for common bacterial gastroenteritis (E. coli, Vibrio, non-typhoidal Salmonella), symptoms like loose stools, vomitting and cramps typically start within 6–72 hours of exposure. For cholera, profuse “rice-water” diarrhoea can begin as early as 12–48 hours after drinking heavily contaminated water. For typhoid and paratyphoid, high-grade fever and abdominal pain usually appear after 7–14 days, so some cases surface even after the immediate outbreak window. For protozoal infections like giardiasis, bloating and chronic loose stools often start 1–2 weeks after exposure and may then persist for weeks if untreated.

This means that after a contamination event, local health systems should stay on high alert not just for the first 48–72 hours but for at least 2–3 weeks, as different diseases “declare” themselves at different times.

Contaminated municipal supplies most commonly transmit “water-borne” infections of the gut, but skin and systemic infections are also possible.

Bacterial diarrhoeal diseases: Acute gastroenteritis can happen because of pathogenic E. coli, Shigella and non-typhoidal Salmonella, causing fever, abdominal cramps and bloody or watery diarrhoea. Cholera, leading to sudden, profuse watery diarrhoea and rapid dehydration, breaks out especially where sewage has mixed with drinking water lines. Typhoid and paratyphoid fever cause prolonged fever, headache, abdominal pain, constipation or diarrhoea and, in severe cases, intestinal perforation.

Protozoal and parasitic infections: Giardia produces chronic foul-smelling diarrhoea, weight loss and malabsorption, particularly in children. Cryptosporidiosis, which can be severe and protracted in young children, affects the elderly and immunocompromised persons.

Viral and other systemic infections: Hepatitis A and E, presenting with fever, malaise, nausea and later jaundice, often emerging weeks after the initial contamination episode.

Leptospirosis occurs in settings where sewage or flood water mixes with drinking or bathing water, causing high fever, muscle pains and, in severe cases, kidney or liver failure.

These infections disproportionately affect those at the extremes of age, pregnant women and people with chronic illnesses or weak immunity.

Management has two parallel pillars, the clinical care of patients and public health control of the source.

For individual patients, early supportive care saves more lives than any single drug. Rehydrate the patient with oral rehydration solution (ORS) for mild to moderate dehydration, emphasising small, frequent sips.

Administer Intravenous fluids with electrolytes for patients with severe dehydration, persistent vomiting, altered sensorium or shock.

Targeted antimicrobials are recommended after clinical assessment and, where possible, stool/blood tests. Antibiotics are to be given for only confirmed or strongly suspected bacterial infections such as cholera and typhoid, following national and WHO guidelines. Antiparasitic agents like metronidazole or similar drugs are to be given for giardiasis and other protozoal infections.

Symptomatic medicines (antiemetics, antispasmodics) are to be used judiciously. Antimotility agents are generally avoided in high-fever or bloody diarrhoea.

(Dr Vishal Khurana is director, gastroenterology, Metro Hospital, Faridabad)