A typical scenario (an illustrative story based on situations we see often, not a review from a specific customer)

A back storeroom in Sukhothai, and tiny footprints in the dried mud

The two-storey shophouse near the Yom River in Sukhothai town is both home and grocery store for Somchai's family. This year the river spilled into town and knee-deep water sat in the streets for days. The shopfront and the stockroom behind it were completely submerged. While the water was high, the family watched large rats swim in and climb onto the shelves, scrambling up door frames and window ledges, driven out of drains and burrows that were now underwater.

When the water went down, Somchai and his son rushed to reopen. They waded through mud in flip-flops, carried soaked boxes out with bare hands, picked up torn rice sacks and wiped the roller shutter with a wet cloth. The dark, stuffy stockroom at the back was coated in dried mud marked with tiny footprints, and droppings lay in every corner. Each time the door opened, a sharp ammonia-like smell mixed with rotten mud rolled out.

Four days later Somchai's 25-year-old son developed a sudden high fever, a pounding headache and calf pain so severe he could barely walk downstairs. Both eyes were red. At first the family blamed a cold from all the wet work, until his mother remembered a TV warning about leptospirosis after floods and took him to hospital. The doctor asked about wading and the cuts on his feet and started treatment quickly. Because he arrived early, he recovered steadily.

Back home, the family had questions. Is the bacteria still in our house? Is the storeroom safe to sort through? What about customers walking into the shop? This article answers those questions, from the nature of Leptospira and safe cleanup to the role ozone plays in restoring homes and shops after a flood.

Understanding Leptospira, the cause of leptospirosis

Leptospirosis is caused by spiral-shaped bacteria of the Leptospira group that live in the kidneys of many animals, above all rats, but also dogs, cattle, buffalo and pigs. Infected animals shed the bacteria in their urine continuously, often without looking sick. Once urine contaminates water, mud or damp surfaces, the bacteria can survive for a long time in wet conditions out of direct sunlight.

Why floods raise the risk

• Rats are flushed out of their nests. When sewers, burrows and the space under raised houses flood, rats move to higher ground, which usually means homes, shops and warehouses.
• Urine spreads with the water. Floodwater carries contamination from drains, rice fields and rubbish heaps into buildings and leaves it in the mud when it recedes.
• Dark, damp spaces protect the bacteria. Storerooms, under-stair cupboards, the space behind cabinets and sunless corners let them survive far longer than an open, sunny yard.
• People handle more mud and water. Cleanup is when people touch the most contaminated material, often without protective gear.

How the bacteria enter the body

Leptospira enters through cuts, grazes and tiny scratches, through skin softened by long soaking, and through the mucous membranes of the eyes, nose and mouth: rubbing eyes with muddy hands, eating or drinking something contaminated, or splash-back while hosing floors. Inside a flooded home, common unnoticed contact points include:

• Floors with mud residue and small puddles.
• Door edges, handles, roller shutters and window frames that rats climbed during the flood.
• Storerooms, shelving, cardboard boxes and sacks where rats sheltered.
• Under kitchen sinks, pipe openings and ground-floor bathrooms connected to drains.
• Boots, gloves and rags left wet after cleaning.

A room-by-room look: floors, doors and storerooms

Floors. Tiled floors look clean quickly, but grout lines, the gap under skirting boards and the joints of wooden or laminate floors trap fine silt that stays damp. Rats that sheltered indoors during the flood also mark their routes with urine along the base of walls, exactly where people later kneel to scrub.

Doors. Door leaves, frames, thresholds and roller shutters are both rat climbing routes and the surfaces every family member touches dozens of times a day. Wooden frames that soaked up water can hold contamination in the grain, and handles are an easy path from surface to hand to eye.

Storerooms. These are the highest-risk rooms in most flooded homes and shops. They are dark, poorly ventilated, full of cardboard and sacks that rats nest in, and often the last place anyone cleans. Paper and fabric absorb urine and hold the smell, while the floor beneath stacked goods stays wet far longer than open areas. Treat any storeroom that flooded as contaminated until it has been emptied, washed, dried and disinfected.

Symptoms you must know

Symptoms often begin around one to two weeks after exposure, though they can appear sooner or later. Common signs are sudden high fever, chills, severe headache, intense muscle pain especially in the calves and thighs, red eyes, nausea, vomiting and sometimes diarrhoea. Severe cases can bring yellow skin and eyes, reduced urine, kidney failure, coughing blood or bleeding in the lungs, which can be fatal.

Critical: anyone who has waded through floodwater, cleaned up after a flood or handled mud and then develops fever and muscle pain, particularly in the calves, must see a doctor immediately and mention the flood exposure. Do not self-medicate with fever pills and wait. Leptospirosis responds well to early treatment. Ozone treats the environment; it does not prevent or treat infection in the body. See the Department of Disease Control for more information.

Who is most at risk

• Whoever is cleaning homes and shops, especially with cuts on hands or feet.
• Farmers and field workers returning to flooded land.
• Older adults and people with chronic illness such as diabetes or kidney disease, who face higher complication risks.
• Children who play in water and on floors and put hands to mouth and eyes.
• Pregnant women, who should avoid wading and direct contact with mud.

What lingering contamination costs a household or business

Health

The danger does not leave with the water. As long as wet mud remains in corners or rats still visit the storeroom, people can be re-exposed, especially in the days and weeks after the flood when everyone is moving things and scrubbing hard.

Money

Leptospirosis can mean a hospital stay; severe cases may need dialysis or intensive care. Families lose treatment costs, travel costs and income while off work. For shops, any stock rats gnawed or urinated on must be discarded, a loss many owners don't anticipate.

Time

Many households clean the same space again and again because they are never sure it is truly clean. The pungent smell of rat urine soaked into floorboards, tile grout and cardboard makes the home feel unready for normal life.

Business reputation

For grocery stores, restaurants, dormitories and homestays, customer trust is everything. Droppings, a sharp smell or news that someone at the shop caught leptospirosis travels fast through the neighbourhood and social media. Restoring a shop systematically protects long-term income.

Family anxiety

Once one person gets sick, everyone wonders who is next. Parents stop children playing downstairs; grandparents avoid the kitchen. Not feeling safe in your own home is a heavy emotional burden.

Why ordinary cleanup is not enough for leptospirosis risk

1. High-pressure hosing turns contamination into spray

A pressure washer clears mud quickly, but the mist it throws up can carry bacteria into the eyes, nose and mouth of whoever is cleaning, especially in tight spaces such as storerooms and bathrooms. Wear goggles and a mask, and use a moderate pressure.

2. One cloth for the whole house

A single rag used from the storeroom through to the kitchen simply moves contamination from the dirtiest spot to the cleanest. Damp cloth is also a good place for bacteria to survive. Use separate cloths for each zone and wash or discard them after use.

3. Disinfecting surfaces still coated in mud

Most disinfectants work poorly on surfaces covered with mud or organic matter. Wash the mud away first, then disinfect, and leave the product in contact for the time the manufacturer specifies rather than spraying and wiping straight off.

4. Forgetting rat runways and hiding places

Rats travel along walls, up door edges, pipes and cables, and hide behind shelving, under cupboards and inside stacks of cardboard. These spots are rarely cleaned because they are hard to see or reach, so urine and droppings stay behind for a long time.

5. Masking the ammonia smell with fragrance

A sharp, ammonia-like smell in a storeroom is a sign that rat urine has soaked into materials. Spraying perfume over it creates a false sense that the room is clean while the source remains.

6. Cleaning without closing the entry points

If there are gaps under doors, open drain pipes without grilles or food left uncovered, rats will return and every round of cleaning starts again.

Recovering a flooded home with leptospirosis risk therefore needs a clear sequence: protect yourself, remove mud and wash, discard heavily contaminated items, dry the space, seal rat entry points, then disinfect the whole area. Ozone completes that final step more thoroughly than hand-wiping can.

WHD residential ozone disinfection: finishing flood recovery for homes and shops

World Health Disinfection (WHD) offers residential and building ozone disinfection for houses, condominiums, shophouses, dormitories, hotels, offices, factories, schools and hospitals. Ozone gas (O3) is released into a closed space, where it spreads throughout the room and reaches behind shelving, under cabinets, around door frames and along the gaps rats use as runways, all places that are hard to clean by hand.

Ozone breaks down the cell structures of bacteria, viruses and mold and breaks apart odour molecules, including the pungent smell of rat urine and the stench of rotting mud. Afterwards it reverts to oxygen (O2) and leaves no chemical residue, which matters a great deal for shops that sell food and household goods. According to the company, the process has been tested and certified by Thailand's Department of Medical Sciences and Intertek (UK), eliminating viruses, bacteria and mold by 99.99% according to the test results certified to the company. See the certification documents.

Safety: ozone treatment is done only in an empty, closed space. People, pets and plants must leave the area entirely and may re-enter only after the rest and ventilation period set by the team. Shops should close to customers during treatment.

The facts: ozone does not replace mud removal, washing, discarding contaminated stock, drying or rodent control, and it does not protect anyone from infection while wading or handling mud outside. Anyone with symptoms must see a doctor. Ozone is the finishing step that reduces remaining microbes across the whole space and removes odours, so the family can use the area again with more confidence.

Our process for homes and shops with signs of rats

1. Enquiry and assessment: flood depth, where droppings or ammonia smells were found, storeroom size, and whether the building is purely residential or has a shopfront.
2. Readiness check: confirm mud, damaged stock and rubbish are gone and floors are washed and reasonably dry.
3. Zoning and preparation: open cupboards, drawers and storerooms; pull shelving slightly away from walls so gas can circulate; close windows and shutters; move people, pets and plants out.
4. Ozone release: generators placed zone by zone, typically about 30 minutes per zone. Storerooms with strong odours may be given extra planning.
5. Contact time: concentration held so ozone can react with microbes and odour molecules throughout.
6. Rest and ventilation: machines off, ozone allowed to revert to oxygen, then the area is aired before anyone returns.
7. Handover and advice: keeping stock off the floor, sealing entry points and ongoing cleaning routines.

Ozone jobs of 15,000 baht or more include a free medical-grade disinfectant spray, useful for daily wiping of door handles, counters and shelves.

10 reasons homes and shops at leptospirosis risk should finish with ozone

1. It reaches rat runways and hideouts behind shelves, under cabinets, around door frames and pipe gaps that cloths cannot reach.
2. It treats the whole room at once, so no risky spot is forgotten.
3. It removes the ammonia smell of rat urine and the stench of rotten mud at the source.
4. No chemical residue on shelves and stock areas, ideal for grocery stores and restaurants. Learn more about ozone and chemical residue.
5. Less exposure for the people cleaning, who no longer need to scrub stuffy corners again and again.
6. Backed by testing from the Department of Medical Sciences and Intertek, 99.99% according to the test results certified to the company.
7. Reopen quickly: about 30 minutes per zone plus ventilation, so small shops often reopen the same day.
8. Customer confidence: a shop that has been systematically disinfected can say so honestly. See service details.
9. Professional safety control of zones, concentration and timing.
10. A fresh start for hygiene, with advice on rodent-proofing and ongoing care. Book the team.

Example case: a Hat Yai bungalow and the back door rats used as an entrance

Example case to illustrate the recovery sequence, not a testimonial from an identified customer.

Nid, a 52-year-old dessert seller, lives with her 80-year-old mother and two grandchildren in a single-storey house in Hat Yai, Songkhla. Floodwater about knee-high stayed for three days. Afterwards she found droppings on the kitchen floor and in the drawer under the sink, and gnaw marks on the back door frame, which had softened in the water. The small storeroom holding flour, sugar and packaging reeked.

First, her mother and the children went to stay with relatives during cleanup. Nid and her brother wore rubber boots, thick rubber gloves and goggles, shovelled out the mud, threw away every ingredient that had been wet or showed rat signs, washed floors and cupboards with detergent and let everything dry with the windows open. A carpenter replaced the back door frame and fitted a rodent strip under the door, and grilles went over the drain openings.

With the house dry and sealed, the WHD team treated it in two zones: kitchen plus storeroom, then bedrooms and living room. The family stayed out through treatment and ventilation. Afterwards the storeroom smell was gone. Nid moved fresh ingredients into lidded plastic boxes on raised shelves and went back to making desserts to sell. The lesson: ozone works best after rat entry points are sealed; otherwise new rats simply bring contamination back.

Leptospirosis prevention and recovery checklist

Protect yourself during cleanup

• Wear rubber boots, thick rubber gloves, goggles and a mask. Never walk through mud barefoot or in sandals.
• Cover any cuts on hands and feet with waterproof plasters before starting.
• Don't rub your eyes, touch your face or eat while cleaning.
• Wash with soap and shower as soon as you finish.
• Keep children, older adults and pregnant women away from active cleanup areas.

Before ozone

• Remove all mud; wash floors, doors, window ledges and shelving with clean water and detergent.
• Throw away food, ingredients and stock that touched floodwater or show rat signs.
• Soak droppings with disinfectant before picking them up. Never dry-sweep, which raises dust.
• Seal gaps under doors, fit grilles on drain openings and repair rotten frames.
• Dry the space with ventilation and dehumidifiers.

On treatment day and afterwards

• Everyone, including pets and plants, leaves; no re-entry until the team confirms ventilation is complete.
• Store food in lidded containers and keep stock off the floor.
• Empty rubbish daily into lidded bins and never leave food scraps overnight.
• Keep wiping high-touch surfaces with a suitable disinfectant, for example Chemgene disinfectant.
• If anyone develops fever, calf pain or red eyes in the weeks after the flood, see a doctor immediately.

Frequently asked questions

1. Does ozone treatment mean we can't catch leptospirosis?

No. Ozone reduces residual microbes inside the home after cleaning. It does not protect against infection from wading or touching mud outside, and it is not a treatment. Protective gear and prompt medical care for symptoms are always essential.

2. When should we book ozone?

After mud removal, washing, discarding contaminated items, drying and sealing rat entry points, so the ozone can deal with what remains and with odours as effectively as possible.

3. How long must a shop close?

Typically about 30 minutes per zone plus rest and ventilation. Small shops often reopen the same day. The team gives exact timing after assessing the space.

4. Can flood-soaked stock be sold after ozone treatment?

No. Food, ingredients and products whose packaging was soaked or shows rat signs should be discarded. Ozone disinfects the space; it does not make contaminated goods safe again.

5. Does ozone get rid of rats?

Ozone is not rodent control. Rats are kept out by sealing entry points, storing food securely and managing rubbish. For a heavy infestation, use a pest control service alongside disinfection.

6. When can children and grandparents sleep downstairs again?

Once mud is gone, surfaces are washed and dry, rat entry points are sealed and the space has been disinfected and fully ventilated. Keep watching for new droppings or smells in the following weeks; if they reappear, rats are still getting in and the entry points need another check.

7. How do we get a quote?

Send photos, room sizes and flood depth via LINE @whd268 or call 065-556-6294. The team will estimate zones and a preliminary price. Jobs from 15,000 baht include a free medical-grade disinfectant spray.

Ready to move back in and reopen with confidence?

Let WHD complete your flood recovery with room-by-room ozone disinfection that removes odours and leaves no chemical residue.

Book Ozone Disinfection

Call 065-556-6294  |  LINE @whd268  |  worldhealthdisinfection@gmail.com

Related pages

• Residential and building ozone disinfection
• Disinfection service
• Contact us

References

• World Health Organization fact sheets
• CDC: Floods and cleanup safety