When the floodwater goes down, the clean-up starts: wading through mud, scrubbing floors, clearing drains. That is also when one of the most common post-flood infections in Malaysia gets its chance.
Leptospirosis, known locally as penyakit kencing tikus ("rat urine disease"), is a bacterial infection that can be serious, and its early symptoms look a lot like the flu. Here's what to know as the northeast monsoon gets going.
This is general health information, not a diagnosis. If you're unwell after floodwater contact, see a doctor.
How it spreads
Leptospirosis is caused by Leptospira bacteria. Infected animals, most famously rats but also other animals including livestock and dogs, shed the bacteria in their urine, which contaminates water and soil.
People are usually infected when that water or mud gets into the body through:
- cuts, scratches or broken skin, especially on the feet and legs;
- the eyes, nose or mouth, for example from splashing or swallowing water.
Floods spread contaminated water over large areas. Research on Malaysia has linked many cases to flood periods, and the risk tends to rise during the rainy season.
It isn't only floods. Recreational water is a known source too: in May 2026, a recreation park in Kuala Pilah was closed for cleaning after suspected cases linked to water activities there.
Who is most at risk
- People wading through floodwater or cleaning up flooded homes and drains.
- Workers in agriculture, plantations, sewage, sanitation and animal handling.
- People who swim or bathe in rivers, waterfalls and lakes, especially after heavy rain.
- Anyone with open wounds exposed to mud or water.
The symptoms, and why the timing matters
Symptoms usually appear days to a couple of weeks after exposure. By then, many people don't connect them to the flood.
Common early symptoms include:
- sudden fever and chills
- headache
- muscle pain, often in the calves and lower back
- red eyes
- nausea, vomiting or diarrhoea
Many cases are mild. Some become severe and affect the kidneys, liver, lungs or brain. Warning signs include yellowing of the skin or eyes, passing little urine, breathlessness, coughing blood, or confusion. These need urgent care.
What to do if you feel unwell
- See a doctor promptly and say you were in floodwater, mud or a river, and when. That history changes what a doctor looks for, because early leptospirosis can be mistaken for dengue, flu or other fevers.
- Don't self-medicate with leftover antibiotics. Leptospirosis is treated with antibiotics, but a doctor needs to decide which and how long.
- In an emergency, call 999. Our guide to calling 999 in Malaysia explains what to say.
Treatment works best when it starts early, which is why the floodwater history matters.
Lowering your risk during a clean-up
- Wear boots and gloves when wading or cleaning. Long rubber boots are worth having before the season starts.
- Cover cuts and wounds with waterproof dressings, and wash any wound that gets wet with clean water and soap.
- Avoid swimming or playing in floodwater, and keep children out of it.
- Wash your hands and shower after contact with floodwater or mud.
- Clear rubbish and food waste that attracts rats, and store food in sealed containers.
- Avoid rivers and waterfalls after heavy rain, and heed any closure notices.
For the wider picture of post-flood health risks, see our piece on why the health risk comes after the water drops. For flood warnings themselves, here's how to read Public Infobanjir and MET alerts.
FAQ
What is kencing tikus?
Kencing tikus is the local name for leptospirosis, a bacterial infection spread through water or soil contaminated with the urine of infected animals, such as rats.
How long after a flood do leptospirosis symptoms appear?
Symptoms usually appear within days to a couple of weeks after exposure, which is why people often don't link them to the flood.
Is leptospirosis contagious between people?
Person-to-person spread is very rare. People are usually infected through contaminated water or soil entering cuts or the eyes, nose or mouth.
Can leptospirosis be treated?
Yes. It is treated with antibiotics prescribed by a doctor, and treatment works best when it starts early. Severe cases may need hospital care.