A typical scenario: a family that raised the floor almost to the roof

This example case is built from situations that commonly follow floods. It is not the story of any particular family.

Aunt Daeng lives with her daughter, son-in-law and two-year-old grandson in a single-storey house in Sena. This year the water came faster and higher than expected. As Thairath reported in October 2026, homes in Sena flooded nearly 1 metre deep and residents had to build their floors up to escape the water until they were almost touching the roof. Aunt Daeng's family was one of them. Everyone slept, ate and looked after the toddler on a raised wooden platform squeezed under the roof.

The hardest part was not the cramped space. It was the bathroom. It was under water and the toilet could not be used. The family relied on sanitation bags and a plastic bucket. Clean water for hand washing was scarce because it had to be saved for drinking and cooking. The baby's nappies were changed on the same platform where the family ate.

When the water began to fall, they came down to floors covered in mud, a waist-high tide line on the walls and a bathroom that smelled of the septic tank. On the third day the grandson developed a fever, frequent loose stools and cramps. His mother noticed mucus in the stool and took him straight to hospital. The doctor said they would need to wait for the stool test and told the whole family to wash their hands carefully with soap, because some diarrhoeal diseases pass through a household very easily. After that, Aunt Daeng began to see her home differently.

The 2026 floods in Sena and Ayutthaya: what the news reported

Only reported facts are used here, to give context.

• Thairath (October 2026) reported that homes in Sena district flooded nearly 1 metre deep, and residents raised their floors to escape the water until they almost reached the roof.
• Manager Online (3 October 2026) reported that 16 districts of Phra Nakhon Si Ayutthaya province were affected, totalling 48,704 households.

The picture of people living just under the roof says a lot about hygiene. When a whole family spends days on a small raised platform, keeping eating, sleeping and toileting areas apart is almost impossible, and clean water for hands runs short. Those are ideal conditions for diseases that spread from faeces to mouth, such as Shigella dysentery. The risk does not end when the water goes down, because germs left in mud and on surfaces are still waiting for the next hand.

What is Shigella?

Shigella is a rod-shaped Gram-negative bacterium that causes shigellosis, or bacillary dysentery. Thai speakers call it "dysentery without a creature" to tell it apart from amoebic dysentery, caused by the parasite Entamoeba histolytica. Both can cause stools with mucus or blood, but they are different organisms and need a doctor's diagnosis.

There are four main species: Shigella dysenteriae, Shigella flexneri, Shigella boydii and Shigella sonnei. All infect humans. The bacteria invade the lining of the large intestine, causing inflammation and small ulcers. That is why mucus and blood can appear in the stool, and why patients feel a constant urge to pass stool even when there is nothing left.

Why Shigella spreads more easily than many gut germs

Shigella's defining feature is its very low infectious dose. CDC explains that swallowing only a small number of germs can make a person sick, unlike some germs that need a large dose. In practice, the invisible trace on a fingertip may be enough. That is why dysentery spreads readily in crowded homes, childcare centres and temporary shelters, all of which are common during floods.

CDC also reports that Shigella resistant to several antibiotics is becoming more common. This is not meant to frighten anyone. It underlines that preventing infection in the first place is valuable, and that antibiotics should never be self-prescribed; leave that to a doctor.

How floods spread Shigella

Shigella travels from faeces to mouth, through hands, food, water or objects. Floods open many routes at once.

• Flooded toilets and septic tanks release faeces into the water, which then settles in other homes on floors, walls and furniture.
• Shortage of clean water leads to quick rinses instead of proper hand washing, or none at all.
• Caring for small children in tight spaces. Changing nappies where food is eaten is one of the most common routes.
• A sick person cooking for others. Infected people can spread the germ while ill and for some time after recovering.
• Swallowing flood water while children play or adults wade and get splashed.
• Flies that land on rubbish and waste left after the flood and then on food can carry germs mechanically.
• Shared objects such as door handles, taps, water scoops, stair rails, toys and mobile phones.

Where to focus in a home after the water recedes

In a house that flooded nearly 1 metre deep, every surface below that line sat in water that may have contained faeces. Pay special attention to the whole bathroom, especially the toilet bowl, flush handle, bidet spray, water scoop and floor around the toilet. Then the floors where children crawl or play, door handles, low kitchen cupboards, the dining table, table and bed legs, and plastic toys that floated around. The raised platform the family lived on may not have flooded, but after days of eating, sleeping and changing nappies there, it needs thorough cleaning too.

Symptoms of Shigella dysentery

According to CDC, symptoms usually start one to two days after infection and often last about seven days. Common symptoms include:

• Diarrhoea, which may contain mucus or blood
• Fever
• Stomach pain and cramps
• A constant feeling of needing to pass stool, even when the bowels are empty
• Nausea, tiredness and poor appetite

Some people have mild symptoms or none, yet can still pass the germ on. That is why hygiene at home must involve everyone, not only the person who is ill.

Signs that need a doctor right away

• Bloody stools or stools with mucus and blood
• High fever, or fever that does not settle
• Signs of dehydration such as dry mouth, little urine, drowsiness or dizziness
• A young child with frequent stools, vomiting, refusing drinks, crying without tears or unusual sleepiness
• A young child with high fever and a seizure
• Diarrhoea in older adults, pregnant women or anyone with weakened immunity

Anyone with diarrhoea after a flood should drink enough clean water and oral rehydration solution as advised by health workers, and see a doctor to find the cause. Do not take anti-diarrhoea medicine or antibiotics on your own. This article is not treatment advice. In an emergency, call 1669.

Less common complications include severe dehydration, bloodstream infection and, in some people, joint pain that develops later. Shigella dysenteriae type 1 is also linked to a rare kidney complication. These are all reasons why bloody diarrhoea always needs a doctor.

Who is most at risk

• Children under five. CDC notes that young children are the group most often affected, because they put hands in mouths, cannot yet wash hands well and wear nappies.
• People who care for children or the sick, who handle nappies and waste.
• Older adults, who dehydrate easily and often have other conditions.
• Pregnant women, as fever and dehydration affect both mother and baby.
• People with weakened immunity, for example those on immune-suppressing medicines or cancer treatment.
• People in shelters or crowded homes where several families share one bathroom.
• Anyone who cooks for the family or sells food, who can pass the germ to many people without realising.

Many households in Sena are extended families with babies and grandparents under one roof, so hygiene after the flood protects the most vulnerable members first.

What dysentery costs a family

• Illness passed around the house. When a child falls ill, carers often follow within days; if the family cook is infected, the circle widens.
• Recovery work grinds to a halt. The weeks after a flood need the most energy for cleaning, hauling and repairs, and illness stops all of it.
• Extra costs for hospital trips, medicine and lost wages arrive just as repair bills pile up.
• Stress and guilt. Parents often blame themselves when a child gets sick after the flood, even though conditions made prevention hard. A clear routine reduces that uncertainty.

Why familiar cleaning habits fall short against Shigella

• Rinsing hands with plain water. CDC advises washing with soap and clean water, especially after using the toilet, after changing nappies and before preparing food.
• Relying on alcohol gel instead of soap. Gel helps when there is no water, but when hands are visibly dirty with mud, soap and water remain the main method.
• Scented floor cleaner. A pleasant smell does not mean germs are gone; most cleaners are made to remove dirt.
• Cleaning the toilet bowl but not around it. The flush handle, bidet spray, scoop, bathroom door handle and light switch are touched more than the bowl itself.
• Rinsing toys and leaving them in the sun. Sunlight dries them, but mud in crevices may still hold germs. Soft toys that were soaked should be thrown away.
• One cloth for the whole house. Wiping the bathroom and then the dining table moves germs from one place to another.

CDC and WHO set out the same order: remove mud, wash with clean water and detergent, disinfect surfaces that touched flood water, and dry. With a germ like Shigella, where a tiny dose is enough, how thoroughly surfaces are covered matters as much as the strength of the product.

The first defence nothing replaces: soap and water

Before discussing spraying, it must be said clearly. The most important weapon against Shigella is washing hands with soap and clean water. No service replaces that habit.

• Wash after the toilet, after changing nappies, after handling rubbish or mud, and before preparing or eating food.
• Lather palms, backs of hands, between fingers and under nails for at least 20 seconds, then rinse with clean water.
• Help small children wash every time and keep their nails short.
• Set up a hand-washing point with soap outside the bathroom or front door; if piped water is not back, use a bucket with a tap.
• Change nappies on a wipeable surface away from where food is eaten, and dispose of them in sealed bags.
• People with diarrhoea should not cook for others, and sick children should stay home from school or childcare as a doctor advises.
• Drink boiled or bottled water and discard food that touched flood water.
• Cover food and clear rubbish to keep flies down.

Where World Health Disinfection's spraying service helps

Once hand washing is a habit, the remaining problem is the large area of surfaces that sat in flood water, which cloth wiping rarely covers fully. The disinfection spraying service from World Health Disinfection (WHD) is built for that job. According to the service page, trained technicians spray and/or use ULV (Ultra Low Volume) fogging, turning the disinfectant into a fine mist that reaches the flooded part of walls, the undersides of furniture, door gaps and wide floor areas quickly.

The product is CHEMGENE HLD4H, a medical-grade disinfectant from the United Kingdom. According to the product information, it contains Benzalkonium Chloride and Didecyldimethylammonium Chloride.

Efficacy as stated by the product and service pages

According to the product and service information, CHEMGENE HLD4H is broad-spectrum against viruses, bacteria and fungi. The website lists SARS-CoV-2 (COVID-19), Human Coronavirus 229E, RSV, influenza H1N1 and H5N1, HIV, norovirus, hand-foot-and-mouth virus, vaccinia virus, mycobacteria, Salmonella and Bordetella pertussis (whooping cough), plus bacteria and fungi in general. The service page claims 99.99% efficacy; the product page states 99.85% against COVID-19 within one minute. The service page also lists the Department of Medical Sciences, Mahidol University, NHS England and EN 14476:2013+A2:2019. For families with small children, it is worth noting that the list includes norovirus and hand-foot-and-mouth virus, which also spread by hands and surfaces, and Salmonella, another gut bacterium.

Being honest about Shigella

Shigella is not among the organisms the website lists with a specific test result. We do not claim any tested kill result for it. What can be said is that Shigella is a bacterium, part of the bacteria group the product says it covers, and that WHO and CDC recommend cleaning and then disinfecting surfaces contaminated by flood water. Childcare centres, schools and organisations that need test data for Shigella specifically can ask WHD directly.

How the service works, according to the service page

1. Book by phone on 065-556-6294 or LINE @whd268, describing the size of the home, how high the water reached and areas of concern such as the bathroom or play corner.
2. Prepare by removing mud, washing floors, walls and furniture with clean water and detergent, discarding what cannot be cleaned, and packing dishes, baby bottles and children's things in closed boxes.
3. Technicians spray while everyone, especially young children, older relatives, pregnant women and pets, stays out of the zone.
4. Wait about 30 minutes, according to the service page, re-enter at the technicians' time and open windows.
5. Use the space again, wiping surfaces that children may mouth or that touch food as the technicians advise.

Spraying always follows mud removal. It does not replace cleaning, and we do not claim it leaves no residue, which is why people leave during spraying and follow the re-entry time.

10 reasons Sena homes should be sprayed after the flood

1. A tiny dose can cause illness, so coverage must be thorough, not just the spots that look dirty.
2. The bathroom is the centre of the problem, and technicians can treat all of it, including lower walls, behind the toilet and around drains.
3. A home flooded nearly 1 metre deep has too much surface to wipe by hand. ULV fogging covers walls and furniture quickly. See the disinfection service.
4. It protects crawling babies by treating floors and play corners before children return.
5. Several gut germs at once. The product lists norovirus, Salmonella and bacteria in general.
6. Medical-grade product instead of home mixing, avoiding wrong bleach dilutions or dangerous chemical combinations.
7. Extended families can move back together with more confidence.
8. Short wait, about 30 minutes according to the service page.
9. Experience with demanding sites including hospitals, schools, malls, airports, offices, airlines, banks and residential buildings. Learn more.
10. Tools for daily upkeep. The promotion includes a free CHEMGENE spray bottle and WELLGIENIC wet tissues, and a tax invoice is available.

Before and after spraying: the bathroom and the children's corner

This comparison describes the process, not laboratory results.

Example case: a community childcare centre before reopening

An illustrative example to explain the process. Names and details are fictional.

Teacher Noi runs a small community childcare centre in Sena district. Water entered the single-storey building up to table height, ruining nap mats, toys and picture books. Parents wanted it open quickly so they could return to work, but Noi knew childcare centres are among the easiest places for dysentery to spread.

Teachers and parents shovelled out mud, threw away mats, soft toys and wet books, washed tables, chairs and plastic toys with detergent, and scrubbed the children's toilets and sinks. Only then did they book a spraying team, which focused on the children's bathroom, the nappy-changing corner, classroom floors, door handles and dining tables. Everyone waited outside, returned at the time given and wiped the dining tables as advised before use.

Before reopening, Noi posted hand-washing steps at the sinks, added hand-washing time before meals and after the toilet, and asked parents to keep children with diarrhoea or fever at home and see a doctor. Spraying, she said, was only one step among many, but it reassured parents that nothing had been skipped.

Recovery checklist for families worried about dysentery

Before spraying

• Have an electrician check flooded wiring before switching power back on.
• Wear boots, rubber gloves and a mask while cleaning.
• Remove mud and wash floors, walls and furniture with clean water and detergent.
• Scrub the whole bathroom and make sure the toilet flushes without backflow.
• Discard mattresses, soft toys and food that touched flood water.
• Wash plastic toys with detergent and keep them in a separate box.
• Pack dishes, baby bottles and toothbrushes in closed containers.
• Use different coloured cloths for the bathroom and the rest of the house.

During and after spraying

• Everyone and all pets leave the sprayed zone and return at the technicians' time.
• Open windows and wipe food-contact surfaces as advised.
• Keep a soap station near the bathroom and kitchen.
• Wipe door handles, taps and switches daily in the first week.
• Watch for diarrhoea, fever or bloody stools and see a doctor at once.
• If the house smells musty or walls stay damp, consider residential ozone disinfection as an add-on.

Frequently asked questions

What is the difference between bacillary and amoebic dysentery?

Bacillary dysentery is caused by Shigella bacteria; amoebic dysentery by an amoeba. Both can cause mucus or blood in the stool, but diagnosis and treatment differ, so see a doctor.

If one person has dysentery, will others catch it?

Easily, because a small dose is enough. Washing with soap after the toilet and before eating, separate towels and frequent bathroom cleaning greatly reduce spread.

Does CHEMGENE definitely kill Shigella?

The website lists no specific test result for Shigella, so no figure should be claimed. Shigella is a bacterium, part of the group the product says it covers. Ask WHD for specific test data.

After spraying, can we wash our hands less?

No. Spraying treats surfaces at a point in time, but hands touch new things constantly. Soap and water remain the first line of defence.

Do we need to clean before spraying?

Always. Mud blocks the disinfectant from reaching surfaces; CDC and WHO advise cleaning first, then disinfecting.

When can young children come back in?

After the re-entry time the technicians give, about 30 minutes according to the service page. Open windows and wipe surfaces children may mouth as advised.

Has your Sena home been cleared of mud? Let our technicians complete the disinfection step before the little ones play on the floor again.

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

Related links and references

WHD services and information

• World Health Disinfection spraying service
• CHEMGENE HLD4H disinfectant
• Residential ozone disinfection

External references

• Thairath (October 2026): report on Sena floods, homes nearly 1 metre deep and residents raising floors almost to the roof
• Manager Online (3 October 2026): Ayutthaya flood situation
• CDC: Shigella (Shigellosis) and Floods and Your Health
• World Health Organization: Fact sheets
• Department of Disease Control, Thailand: ddc.moph.go.th

This article provides general health information, not a diagnosis or treatment advice. Anyone who feels unwell should see a doctor. Product efficacy information is attributed to the product and service pages on the provider's website.