Emergencies & environment
Rainy-season diseases in Indonesia: leptospirosis, dengue, diarrhoea and flu
Symptoms, warning signs and prevention of leptospirosis, dengue, diarrhoea and flu in Indonesia’s rainy season and floods, and when to go to a clinic or A&E.
English edition. Official forms and source documents may be in Indonesian.
QUICK ANSWER
What are the symptoms and warning signs of leptospirosis, dengue, diarrhoea and flu in the rainy season, and when should I go to A&E?
In the rainy season and floods, four illnesses to watch for are leptospirosis from rat urine in flood water and mud, dengue fever from Aedes aegypti mosquitoes, diarrhoea from contaminated water and food, and flu and other respiratory infections. Get medical help promptly for a fever after contact with flood water, for dengue warning signs such as nose or gum bleeding, persistent vomiting, stomach pain or cold hands (even after the fever has gone down), for signs of dehydration, or for breathlessness. To prevent them, avoid flood water or wear rubber boots, do 3M Plus every week, wash your hands with soap, drink water boiled until it bubbles, and cover your coughs.
See 11 official references ↓Health information on the Ministry of Health’s Ayo Sehat ↗ayosehat.kemkes.go.id
Guide contents
What to keep at home
- A thermometer to monitor fever.
- Oral rehydration salts (oralit) to replace fluids and electrolytes during diarrhoea.
- Rubber boots and rubber gloves for cleaning up after a flood.
- Soap and clean water, plus drinking water boiled until it bubbles.
- Mosquito repellent and a mosquito net.
- Your BPJS Kesehatan card or the Mobile JKN app, and the addresses of the nearest puskesmas and hospital emergency department.
How to prevent and handle rainy-season diseases
Protect yourself from flood water and mud
Avoid walking through standing water or floods. If you have to, including when cleaning your home, wear rubber boots, gloves and clothes that cover your skin, and keep wounds out of the water. Afterwards, wash with soap before touching your face or food. Do not let children play in flood water.
Do 3M Plus every week
Drain (menguras) and cover (menutup) water containers, and recycle (mendaur ulang) junk that can collect rainwater. The ‘Plus’ steps include mosquito repellent, window and vent screens, fish that eat larvae, larvicide in containers that are hard to drain, and clearing blocked gutters. Check for mosquito larvae once a week.
Keep water and food clean
Wash your hands with soap before eating or drinking and after using the toilet. Boil drinking water until it bubbles, because shallow wells are easily contaminated in floods. Keep food in closed containers and keep rubbish away from your home.
Stop coughs and colds spreading
Wash your hands with soap and water, cover your mouth and nose when you cough or sneeze, wear a mask when you are ill or in crowds, and keep your distance from others while ill. The Ministry of Health recommends a flu vaccination every year to lower the risk of serious illness.
Care for and monitor mild symptoms at home
Get anyone with a high fever (38°C or above) checked at a health facility. With diarrhoea, start oral rehydration salts early to replace fluids and electrolytes. For mild flu, rest, drink plenty of water, eat nutritious food and keep an eye on how you are.
Go to A&E straight away if danger signs appear
Do not wait. Go to the nearest hospital emergency department (IGD) or call 119 for breathlessness or fast breathing, chest pain, fits, difficulty waking, blue lips or face, dengue warning signs or signs of severe dehydration. Tell staff if you have been in flood water or mud in the past two weeks.
Cost of prevention and treatment
The prevention steps in this guide cost little or nothing. The 119 medical emergency service is free. Examination and treatment costs depend on your JKN (BPJS Kesehatan) membership; check your status in Mobile JKN.
| Illness | How it spreads | Early symptoms | Get medical help promptly if |
|---|---|---|---|
| Leptospirosis | Leptospira bacteria from the urine of infected animals, especially rats, via flood water, mud, soil or contaminated food; enters through cuts or mucous membranes. | Fever, headache, muscle and calf pain, tiredness, red eyes; usually about 10 days after exposure. | Fever, muscle pain, headache or red eyes after contact with flood water or mud. |
| Dengue fever (DBD) | Bites from Aedes aegypti mosquitoes, which breed in standing water. | High fever (up to 40°C), severe headache, pain in the muscles, joints and behind the eyes. | Nose or gum bleeding, persistent vomiting, stomach pain, listlessness or restlessness, gasping breaths, little urine in 4–6 hours, paleness, heavy sweating or cold hands, even if the fever has gone down. |
| Diarrhoea | Contaminated drinking water and food, poor sanitation and unwashed hands. | Loose stools more than 3 times in 24 hours, stomach cramps, nausea or vomiting, fever. | Signs of dehydration (dry mouth and lips, sunken eyes, very weak or hard to wake, little or no urine), bloody stools, or getting worse. |
| Flu (respiratory infection) | Droplets from coughing, sneezing or talking. | Fever, cough and runny nose, sore throat, muscle pain and headache, severe tiredness. | High fever lasting more than 3 days, breathlessness or fast breathing (in children, the chest pulling in), chest pain, extreme weakness, fits, difficulty waking, trouble drinking, blue lips or face, or improving then getting worse again. |
The Ministry of Health recommends a yearly flu vaccination and asks regions to inform people about dengue vaccination outside the routine programme (described as ‘imunisasi mandiri’). Ask your puskesmas, clinic or hospital about availability and cost.
Leptospirosis: watch for fever after a flood
Leptospirosis is caused by Leptospira bacteria and spreads through the urine of infected animals, especially rats. It passes through water, mud, soil or contaminated food, so the risk rises after floods and landslides. The bacteria enter through open wounds, mucous membranes, or contaminated drinking water and food.
Early symptoms look like an ordinary fever: fever, headache, muscle pain, calf pain and tiredness, about 10 days after exposure. If treated late, leptospirosis can damage the kidneys, liver and lungs, cause bleeding and even death. In Director General of Disease Control Circular PV.03.03/C/5559/2025, the Ministry of Health asked health facilities to consider leptospirosis for acute fever with exposure in the past two weeks.
So if you have a fever, muscle pain, headache or red eyes after contact with flood water or mud, get checked promptly and tell staff about the exposure. For information, Halo Kemenkes can be reached on 1500-567.
Dengue fever (DBD) and 3M Plus
Dengue is spread by Aedes aegypti mosquitoes, which breed in standing water such as bathtubs, buckets, old cans and tyres, and gutters. It starts with a high fever that can reach 40°C, a severe headache and pain in the muscles, joints and behind the eyes.
Director General of Disease Control Circular HK.02.02/C/861/2026 (18 February 2026) asks people to go to a health facility promptly for warning signs: nose or gum bleeding, persistent vomiting, stomach pain, listlessness or restlessness, gasping breaths, little urine in 4–6 hours, paleness, heavy sweating or cold hands. Warning signs usually appear on days 3 to 7 of the fever as the temperature falls, so a falling fever does not mean the patient is out of danger.
The main prevention is mosquito-breeding-site control (PSN) through 3M Plus all year round: drain, cover and recycle, plus extra steps such as repellent, nets, screens, larva-eating fish and larvicide. The Ministry of Health promotes the ‘one home, one larva monitor’ movement (1 Rumah 1 Jumantik), in which one family member checks the home for larvae once a week.
Diarrhoea and dehydration
In floods, shallow wells are easily contaminated and clean water is scarce in shelters, so diarrhoea spreads quickly. Diarrhoea means passing loose stools more than 3 times in 24 hours. To prevent it, wash your hands with soap before eating and after using the toilet, boil drinking water until it bubbles, and keep your surroundings clean.
The main danger of diarrhoea is dehydration, when the body loses more fluid than it takes in; in children it can happen quickly. Start oral rehydration salts early: dissolve one sachet in 200 ml of boiled water and do not mix it with milk or sweet tea. Other medicines, including antibiotics, only on a doctor’s advice.
Know the signs of dehydration in children: dry mouth and lips, sunken eyes, irritability or extreme weakness, sleeping a lot or being hard to wake, little or no urine, and skin that is slow to settle back after a pinch. If these appear, or there is blood in the stools, take the child to a health facility straight away.
Flu and respiratory infections
Flu is an acute respiratory infection caused by influenza viruses, mostly types A and B in Indonesia, spread by droplets when people cough, sneeze or talk. The Ministry of Health tracks influenza-like illness (ILI) at puskesmas; according to its FAQ of 2 October 2026, flu cases rose in late September 2026 in line with the usual seasonal pattern, not an unusual surge.
Most people recover on their own within about a week with rest, plenty of water and nutritious food. Antibiotics do not treat flu because it is caused by a virus; antiviral medicines are given by doctors only for severe cases or high-risk groups. Young children, older people, pregnant women and people with underlying conditions are more likely to develop complications such as pneumonia.
When to go to a puskesmas and when to go to A&E
Go to a puskesmas or clinic for a high fever (38°C or above), a fever after contact with flood water or mud, diarrhoea that is not getting better, or a cough and cold that will not clear up. Mention any contact with floods, a place with many mosquitoes, or sick people.
Go straight to a hospital emergency department (IGD) or call 119 for breathlessness or fast breathing, chest pain, fits, difficulty waking, blue lips or face, dengue warning signs or signs of severe dehydration. 119 is the Ministry of Health’s free medical emergency service.
Things to check carefully
- Treating a fever after a flood as ordinary and not telling staff about contact with flood water or mud.
- Thinking a dengue patient is safe once the fever drops; that is exactly when warning signs can appear.
- Delaying oral rehydration salts during diarrhoea; they replace lost fluids and electrolytes.
- Asking for antibiotics for flu; antibiotics do not kill viruses.
- Leaving tyres, old cans or blocked gutters to collect rainwater.
- Cleaning up flood mud without rubber boots and gloves, especially with an open wound.
Frequently asked questions
What are the symptoms of leptospirosis?
Fever, headache, muscle pain, calf pain, tiredness and red eyes, usually about 10 days after contact with flood water or mud contaminated by rat urine. It starts like an ordinary fever, so get checked promptly and tell staff about the exposure.
I got a fever after cleaning flood damage at home. What should I do?
Get checked at a health facility promptly and say that you were in flood water or mud. The Ministry of Health asks health facilities to consider leptospirosis for acute fever with exposure in the past two weeks.
What are the dengue warning signs?
Nose or gum bleeding, persistent vomiting, stomach pain, listlessness or restlessness, gasping breaths, little urine in 4–6 hours, paleness, heavy sweating and cold hands. They can appear even after the fever has gone down; go to a health facility promptly.
What is 3M Plus?
3M Plus is how to get rid of dengue mosquito breeding sites: drain and cover water containers, and recycle junk that can hold water. The ‘Plus’ includes repellent, nets, screens, larva-eating fish, larvicide and clearing blocked gutters.
How do I give oral rehydration salts?
Dissolve one sachet in 200 ml of boiled water, stir until dissolved, and do not mix it with milk or sweet tea. Start it early in diarrhoea to replace fluids and electrolytes; if signs of dehydration appear, go to a health facility promptly.
What are the signs of dehydration in a child?
Dry mouth and lips, sunken eyes, irritability or extreme weakness, sleeping a lot or being hard to wake, little or no urine, and skin that is slow to settle back after a pinch. A child with these signs needs to be taken to a health facility straight away.
When should someone with flu see a doctor?
Straight away for a high fever lasting more than 3 days, breathlessness or fast breathing (in children, the chest pulling in), chest pain, extreme weakness, fits, difficulty waking, trouble drinking, blue lips or face, or improving then getting worse again.
Does flu need antibiotics?
No. Flu is caused by a virus, while antibiotics only work on bacteria; doctors give them only if there is an added bacterial infection. For mild flu, rest, drink plenty and eat nutritious food.
Sources and review
Editorial review of public information: . This is not a review by an agency officer or a professional adviser. Reviewed by Kaiser Khan, publisher of Panduan Warga. Official document titles are retained below.
- Kemenkes: siaga leptospirosis pascabencana, SE PV.03.03/C/5559/2025 (17 Desember 2025) ↗kemkes.go.id · Accessed 14 October 2026
- Ayo Sehat Kemenkes: hujan, tikus, dan leptospirosis ↗ayosehat.kemkes.go.id · Accessed 14 October 2026
- Kemenkes: musim hujan, waspadai leptospirosis dan penyakit lainnya ↗kemkes.go.id · Accessed 14 October 2026
- Kemenkes: antisipasi penyakit menular saat banjir ↗kemkes.go.id · Accessed 14 October 2026
- Kemenkes: SE Dirjen P2 HK.02.02/C/861/2026 tentang kewaspadaan KLB dengue (18 Februari 2026) ↗jdih.kemkes.go.id · Accessed 14 October 2026
- Ayo Sehat Kemenkes: PSN 3M Plus ↗ayosehat.kemkes.go.id · Accessed 14 October 2026
- Ayo Sehat Kemenkes: diare pada anak ↗ayosehat.kemkes.go.id · Accessed 14 October 2026
- Ayo Sehat Kemenkes: dehidrasi pada anak ↗ayosehat.kemkes.go.id · Accessed 14 October 2026
- Kemenkes Ditjen Kesehatan Lanjutan: penanganan awal pada diare ↗keslan.kemkes.go.id · Accessed 14 October 2026
- Kemenkes: FAQ influenza (2 Oktober 2026) ↗www.kemkes.go.id · Accessed 14 October 2026
- Kemenkes: layanan kegawatdaruratan medis 119 ↗www.kemkes.go.id · Accessed 14 October 2026
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