💧 Waterborne Diseases: Cholera, Typhoid & Hepatitis A During the Monsoon

The monsoon rains replenish rivers and lakes, but they also wash sewage, animal waste, and harmful bacteria into drinking water sources. When clean water mixes with contaminated floodwater, the result is a sharp rise in waterborne diseases — particularly cholera, typhoid, and hepatitis A. These infections can range from a few days of diarrhoea to life‑threatening dehydration or liver failure. Dr. Ravi Sishir Reddy explains how these diseases spread, their key symptoms, and the simple but powerful steps you can take to keep your drinking water safe.

1. How Water Gets Contaminated During the Monsoon

Heavy rainfall overloads drainage systems and causes sewage to overflow into rivers, lakes, and even piped municipal water supplies. Open defecation, common in many areas, further contaminates surface water. Broken or leaking water pipes can draw in the surrounding contaminated groundwater through negative pressure when the supply is intermittent. As a result, even water that looks clear can harbour millions of disease‑causing bacteria and viruses. The three most common and dangerous waterborne infections in India during the monsoon are:

• Cholera – caused by Vibrio cholerae, leading to severe, rapid dehydration.
• Typhoid fever – caused by Salmonella Typhi, presenting as a prolonged, step‑ladder fever.
• Hepatitis A – caused by the hepatitis A virus, leading to jaundice and liver inflammation.

These three pathogens share a common route: the faecal‑oral route — meaning they are ingested through water or food contaminated with microscopic particles of human faeces.

2. Cholera: The Rapid Dehydrator

Cholera is an acute diarrhoeal illness caused by Vibrio cholerae. The bacteria produce a powerful toxin that causes the intestinal cells to pump out massive amounts of water and electrolytes. The result is profuse, painless, watery diarrhoea that looks like "rice water" — greyish‑white with flecks of mucus. A person with severe cholera can lose 1‑2 litres of fluid per hour, leading to death from dehydration within hours if untreated.

Key symptoms:

• Sudden onset of large‑volume, painless, watery diarrhoea.
• Vomiting — often without preceding nausea.
• Rapid signs of severe dehydration: sunken eyes, dry mouth, absent tears, skin that stays "tented" when pinched, extreme thirst, muscle cramps, and a weak, rapid pulse.
• Fever is usually absent or low‑grade.

What to do: Cholera is a medical emergency. The cornerstone of treatment is rapid rehydration with Oral Rehydration Solution (ORS). In severe cases, intravenous fluids are needed. Antibiotics (doxycycline or azithromycin) can shorten the duration of diarrhoea and reduce the period of infectivity, but rehydration is the life‑saving measure. With prompt treatment, the mortality rate drops from over 50% to less than 1%. If you or someone you know develops profuse watery diarrhoea with signs of dehydration, go to the hospital immediately — do not wait.

3. Typhoid Fever: The Step‑Ladder Illness

Typhoid fever, caused by Salmonella enterica serovar Typhi, is discussed in detail in the Common Infections pillar. During the monsoon, it surges due to contaminated water supplies. Unlike cholera, which causes dramatic diarrhoea, typhoid presents with a gradually rising fever that steps up each day. It is accompanied by headache, abdominal discomfort, a coated tongue, and a slow pulse relative to the height of the fever. The most serious complication is intestinal perforation — a hole in the wall of the small intestine that causes life‑threatening peritonitis. Typhoid requires antibiotic treatment with ceftriaxone, azithromycin, or a fluoroquinolone (depending on sensitivity), and adequate hydration and rest. Without treatment, it can be fatal. A vaccine is available and highly recommended for those living in or travelling to endemic areas.

👉 Read more: Typhoid Fever – Causes & Treatment →

4. Hepatitis A: The Yellowing of the Eyes

Hepatitis A is a viral infection of the liver transmitted through contaminated food and water. After an incubation period of 15‑50 days, symptoms appear abruptly: fever, fatigue, loss of appetite, nausea, vomiting, and abdominal pain, especially in the right upper abdomen. After a few days, the urine becomes dark (like cola), the stools become pale and clay‑coloured, and the skin and whites of the eyes turn yellow (jaundice). The acute illness lasts 2‑6 weeks, and complete recovery can take 3‑6 months. Most people recover fully, but in rare cases, hepatitis A can cause acute liver failure, particularly in older adults and those with pre‑existing liver disease.

There is no specific antiviral treatment for hepatitis A. Management is entirely supportive: complete rest, a nutritious, low‑fat diet, and strict avoidance of alcohol and liver‑toxic medications (including paracetamol in high doses). Hospitalisation is needed if the patient cannot eat or drink due to persistent vomiting or if there are signs of liver failure. The hepatitis A vaccine is safe, highly effective, and given as two doses 6‑12 months apart. Dr. Reddy strongly recommends it for anyone who has not been previously vaccinated, especially those who live in or travel to areas with poor sanitation.

5. How to Make Your Water Safe to Drink

Preventing waterborne diseases is far easier than treating them. Dr. Reddy recommends a multi‑barrier approach to ensure the water you drink is safe:

• Boiling: The simplest and most reliable method. Bring water to a rolling boil for at least 1‑3 minutes. Allow it to cool naturally and store it in a clean, covered container. Boiling kills all bacteria, viruses, and parasites.
• Filtration: Use a high‑quality water purifier that combines reverse osmosis (RO), ultrafiltration (UF), and UV disinfection. RO removes dissolved salts, heavy metals, and most bacteria/viruses; UF physically blocks bacteria and cysts; UV inactivates any remaining organisms. Gravity‑based ceramic or carbon filters are less reliable for removing viruses and do not protect against all pathogens unless combined with chemical disinfection.
• Chemical disinfection: Chlorine tablets or liquid bleach (sodium hypochlorite) can disinfect water in an emergency. Add the appropriate number of drops (usually 2‑4 drops of 1‑5% unscented bleach per litre), shake, and let it stand for at least 30 minutes before drinking. The water should have a faint chlorine smell. This method is effective against bacteria and most viruses but less so against certain parasites like Cryptosporidium.
• Solar disinfection (SODIS): Fill clear PET plastic bottles with water and expose them to direct sunlight for at least 6 hours (or 2 full days if the sky is overcast). The combination of UV radiation and heat kills pathogens. This is a low‑cost method suitable for rural areas with no access to other purification.

Remember: if the water is cloudy, filter or settle it first before disinfection, as particles can shield pathogens from the disinfectant.

6. Food Hygiene: The Second Line of Defence

• Eat food that is freshly cooked and served piping hot. Heat destroys most pathogens.
• Wash fruits and vegetables thoroughly with safe water. Peel them if possible. Avoid raw salads and cut fruits from street vendors during the monsoon.
• Avoid raw or undercooked seafood, eggs, and meat, as they can harbour bacteria and viruses.
• Keep your kitchen and utensils clean. Wash hands with soap before preparing food and after using the toilet.
• Store food in the refrigerator and reheat thoroughly before eating. Discard any food that has been left at room temperature for more than 2 hours.

7. When to See a Doctor or Go to the Hospital

Dr. Reddy advises seeking medical attention immediately if you experience:

• Large‑volume watery diarrhoea (more than 5‑6 motions a day) or vomiting that makes it impossible to keep fluids down.
• Signs of severe dehydration: very dark urine or no urine for >8 hours, extreme dizziness on standing, muscle cramps, sunken eyes.
• Fever above 101°F (38.3°C) that persists for more than 2‑3 days with abdominal pain and constipation or diarrhoea.
• Yellowing of the eyes or skin, dark urine, or pale stools.
• Blood in the vomit or stool.