healthcare

Monsoon Illnesses in Chennai: Leptospirosis, Typhoid, Hep A

Flood water, contaminated food and stored water bring leptospirosis, typhoid, hepatitis A and diarrhoea every monsoon. Here are the warning signs and the habits that prevent them.

19 October 2026

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Dengue gets the headlines, but Chennai’s monsoon also brings a cluster of water and dirt borne infections that tend to be missed until they are serious: leptospirosis from flood water, typhoid and hepatitis A from contaminated food and water, and diarrhoeal disease, which hits small children hardest. Tamil Nadu was one of the original states covered by the national leptospirosis control programme, which now spans 181 districts in 12 states and two Union Territories (NCDC).

The northeast monsoon set in on 15 October. If your street floods every year, the next few weeks are when these illnesses peak. Here is a short guide to each, the warning signs, and the habits that actually prevent them.

Leptospirosis: the flood-water fever

Leptospirosis is a bacterial infection spread through the urine of infected animals, especially rats. People pick it up through contaminated water or soil, mostly after floods or heavy rain, often through cuts on the feet. Symptoms appear anywhere from two to 30 days after exposure (US CDC).

The Union health ministry’s June 2026 monsoon advisory lists fever, headache, muscle pain and weakness as early signs, with calf tenderness, red eyes, reduced urine, jaundice and bleeding in more serious cases. Because early symptoms look like dengue or malaria, tell your doctor if you waded through flood water. Antibiotics work best when started early.

Avoid wading in flood water; if you must, wear gumboots and cover cuts with waterproof dressings.
Wash hands and feet with soap afterwards.
Keep homes and pet areas free of rats and seal holes in walls.

Typhoid and hepatitis A: what you eat and drink

Typhoid is caused by Salmonella Typhi and spreads through food or water contaminated with faeces. It causes a long, high fever with tiredness, headache, stomach pain and either constipation or diarrhoea. A blood test confirms it. WHO notes that antibiotic resistance is common, so finish the course your doctor prescribes and do not buy antibiotics over the counter (WHO). A typhoid conjugate vaccine can be given from six months of age; ask your paediatrician.

Hepatitis A is a viral liver infection that spreads the same way. It usually shows up 14 to 28 days after exposure with fever, loss of appetite, nausea, dark urine and yellow eyes. Adults tend to get sicker than young children. There is no specific antiviral treatment; rest, fluids and food are the treatment, and WHO advises avoiding unnecessary medicines that strain the liver, including paracetamol (WHO). A vaccine is available.

For both, prevention is the same:

Boil drinking water during the monsoon, especially if your supply turns cloudy or smells.
Eat food that is cooked and served hot. Skip cut fruit and raw salads from roadside stalls.
Avoid ice of unknown origin and raw milk.
Wash hands with soap before eating and after using the toilet.

Diarrhoea: watch for dehydration

Most diarrhoea can be managed at home with oral rehydration solution (ORS). For children, WHO recommends a 10 to 14 day course of zinc tablets alongside ORS; it shortens the illness and reduces stool volume (WHO). ORS packets are available at government health centres and pharmacies.

Take a child to hospital at once if you see:

lethargy, drowsiness or unusual irritability
sunken eyes, or skin that goes back slowly when pinched
inability to drink, or drinking very eagerly
blood in the stool
diarrhoea lasting 14 days or more

Other things going around in Chennai

Doctors in the city have been reporting respiratory infections alongside fever this season, including influenza A and RSV in children (News Today). In September, a student’s death from scrub typhus at Anna University prompted the Corporation to clear overgrown bushes on campuses (DT Next). Scrub typhus is spread by mite bites in scrub and grass, so long sleeves help when clearing gardens or vacant plots.

The Corporation runs about 100 fever camps a day and has been distributing Nilavembu kudineer at some of them. A camp is a good first stop for free screening, but it is not a substitute for a hospital if warning signs appear.

Quick answers

How soon after flood water exposure can leptospirosis appear?

Anywhere from two to 30 days, according to the US CDC. Mention the exposure to your doctor even if weeks have passed.

Is paracetamol safe for hepatitis A?

WHO advises avoiding unnecessary medicines that can harm the liver, including paracetamol. Ask a doctor before taking anything.

Are there vaccines for typhoid and hepatitis A?

Yes. A typhoid conjugate vaccine can be given from six months, and inactivated hepatitis A vaccines are available from one year.

Can I treat diarrhoea at home?

Mild cases, yes, with ORS and zinc for children. Seek care if there is blood, drowsiness or signs of dehydration.

This guide is general information only. Consult a doctor for any fever lasting more than a day or two during the monsoon.

Information checked against official sources on 18 October 2026. Fees, dates and rules can change; confirm on the linked official pages before acting.