A flood does more than damage belongings. Once the water goes down, there is a risk of illness, especially if you live in a shared rented room and have to clean up yourself. This article gathers facts from Ministry of Health (KKM) statements and other health sources. It is not medical advice. If you feel unwell, see a doctor.
Information as of 30 Oct 2026. moh.gov.my blocked automated access during our check (HTTP 403), so the KKM statements below come via RTM, CodeBlue and Syok reports. We do not list Johor case numbers because we could not confirm them from two sources.
Background: the rainy season has started
According to The Star (27 Oct 2026), the 2026/2027 Northeast Monsoon began on 27 October 2026 and is expected to last until March 2027. MetMalaysia forecasts three to five episodes of prolonged heavy rain between November 2026 and January 2027.
For preparation before a flood (documents, emergency bag, raising belongings), read our flood-ready checklist for rented rooms in Senai. This article is about health during and after a flood.
Leptospirosis ("kencing tikus"): what is it?
According to Syok (4 Dec 2024), citing a KKM post, leptospirosis is caused by contamination from rat urine. KKM advised people not to play in floodwater.
The US CDC adds:
- The bacteria spread through the urine of infected animals. People can be infected through contaminated water or soil, especially after floods or heavy rain.
- Symptoms usually start 2 to 30 days after exposure. So you can fall ill weeks after the water has gone.
- Symptoms: fever, chills, headache, muscle aches, nausea or vomiting, diarrhoea, red eyes, rash, and yellow skin or eyes. Some people have no symptoms.
- Severe cases can affect the kidneys, liver and brain (meningitis), and can be fatal if untreated.
In a case reported by RTM (14 May 2026) in Kuala Pilah, Negeri Sembilan, patients had fever, headache and muscle pain. The Health Minister advised people to seek treatment at a clinic at the first signs, such as fever.
Lowering the risk during and after a flood
These are points KKM and CDC have made. They are general, not a guarantee.
- Stay out of floodwater. Do not play, bathe or wade without need. The risk is higher if you have cuts or skin problems (KKM, via CodeBlue, Dec 2019).
- If you must wade, wear protective footwear and wash with clean water afterwards (Syok, citing KKM). CDC mentions waterproof boots and covering cuts with waterproof plasters.
- When cleaning up, wear rubber boots and gloves. Change clothes and shower afterwards.
- Do not let rubbish pile up. KKM links containers and rubbish to breeding of rats and mosquitoes (CodeBlue).
- Ask about preventive medicine. In the 2022 floods, Melaka's state health exco encouraged flood victims and relief-centre staff to take preventive medicine against leptospirosis supplied by health workers (RTM, 29 Oct 2022). That was a state decision, not a general order. If you are in a relief centre, ask the health staff there.
Drinking water and food
KKM, via CodeBlue (Dec 2019), advised drinking boiled water and eating clean food. The same statement listed water-borne and food-borne illnesses that can rise after floods, including food poisoning, cholera, typhoid, hepatitis A and gastroenteritis.
A doctor writing in Kosmo (28 Dec 2022) suggests: drink thoroughly boiled or bottled water, eat hot cooked food, peel fruit, avoid raw food, and wash hands with soap. That article is not a KKM statement, but it matches the KKM advice above.
In a shared room: do not keep food that touched floodwater. If power was off for long, the fridge may no longer be safe, and the shared kitchen needs cleaning before use.
Mosquitoes after floods
Standing water after a flood can breed Aedes mosquitoes. Kosmo (2022) advises removing containers that hold water, such as plastic items and tins. KKM (CodeBlue) also links water-holding containers to mosquitoes. For a fuller house routine, see our Johor dengue 2026 guide, including dengue warning signs.
Dengue and leptospirosis can look alike at first (fever, headache, body aches). Do not guess. Tell the doctor you were exposed to floodwater.
When to see a doctor, and where
According to RTM (14 May 2026), KKM advises seeking treatment at a clinic at early signs such as fever. Kosmo (2022) lists fever, diarrhoea and vomiting as reasons to get treatment promptly. CDC recommends seeing a doctor right away if leptospirosis is suspected so tests and treatment can start early.
Useful things to tell the doctor:
- You were exposed to or waded through floodwater, and when.
- You have cuts on your feet or hands.
- When your symptoms started.
Where: a government clinic or hospital, or a private clinic. For costs for foreign patients, SPIKPA and PERKESO, read when a foreign worker falls sick in Johor. We do not list fee rates because we found no official schedule.
Emergency (struggling to breathe, fainting, very yellow skin or eyes, vomiting that will not stop): dial 999. For flood help, 991 is the Civil Defence (APM) line, according to the Malaysia.gov.my portal.
What to do & who to call
| Situation | Action | |---|---| | Have to enter floodwater | Wear boots, cover cuts, shower and change clothes afterwards | | Fever or body aches after a flood | See a doctor at a clinic; say you were in floodwater | | Diarrhoea or vomiting | Get treatment; drink boiled or bottled water | | Life-threatening emergency | 999 | | Flood help, evacuation | 991 (APM) | | Standing water or blocked drain at the house | Tell the house manager with a photo | | Asking about treatment costs | See the SPIKPA guide and ask at the counter |
Common mistakes
- Waiting for a fever to "go away". Symptoms can appear weeks later.
- Not telling the doctor about floodwater.
- Cleaning without boots and gloves.
- Drinking unboiled tap water after a flood.
- Leaving water-holding containers behind the house.
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FAQ
What is "kencing tikus" (leptospirosis)? A bacterial infection spread through animal urine, mainly rats, that contaminates water or soil. KKM advises people not to play in floodwater.
How long after a flood can symptoms appear? According to CDC, usually 2 to 30 days after exposure.
When should I see a doctor? KKM advises seeking treatment at a clinic at early signs such as fever. Tell the doctor if you were in floodwater.
Should I boil drinking water after a flood? KKM advised drinking boiled water and eating clean food.
Do mosquitoes increase after floods? Standing water can breed Aedes mosquitoes. Remove containers that hold water.
Sources
- The Star, Stay alert as northeast monsoon begins (27 Oct 2026) (accessed 30 Oct 2026)
- CDC, About leptospirosis (accessed 30 Oct 2026)
- RTM, Empat kes disyaki kencing tikus stabil (14 May 2026) (accessed 30 Oct 2026)
- Syok, Health Ministry urges to stay out of floodwaters (4 Dec 2024) (accessed 30 Oct 2026)
- CodeBlue, KKM flood health advice (4 Dec 2019) (accessed 30 Oct 2026)
- Kosmo, health advice after floods (28 Dec 2022) (accessed 30 Oct 2026)
- RTM, leptospirosis medicine for flood victims (29 Oct 2022) (accessed 30 Oct 2026)
- Malaysia.gov.my portal, emergency lines 999 and 991 (see our flood guide)
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