A typical scenario: coming back from a shelter to a house that is still damp

Note: this is an illustrative example case based on situations that commonly follow floods in upstream areas of eastern Thailand. It does not describe any real person or family in Kaeng Hang Maeo.

Auntie Somjai is in her sixties and lives with two grandchildren in a low wooden house with a concrete kitchen added at the back. After several days of heavy rain, the stream near her home rose faster than anyone expected. The village head asked older residents and children to move to a temporary shelter first, so she packed her documents and daily medicines into a plastic bag and left with her neighbours.

Days later, as the water began to drop, the family opened the front door to a palm-thick layer of brown mud, tide lines on the wooden walls, soaked mattresses and a musty smell with a hint of sewage. At the shelter some children had started coughing, and Auntie Somjai had itchy toes from wading back to check the house. Her son called from another province to ask where to start and which illnesses to watch for. Those questions are why this article exists.

Where it flooded in Kaeng Hang Maeo: the reported facts

These are the only facts about the area that we use, from the Public Relations Department (prd.go.th) report of 27 September 2026, 11:00:

• Flooding affected 9 districts, 31 subdistricts and 163 villages in Chanthaburi province, a total of 1,508 households.
• In Kaeng Hang Maeo, an upstream district, the water level had started to fall but remained high.
• Temporary shelters were set up in Kaeng Hang Maeo and Na Yai Am districts for affected residents.

The report names no villages or roads and gives no depths, so we add none. Follow the district office and provincial disaster prevention office for current information.

Two things follow: homes soak for days, so moisture gets deep into wood and plaster, and shelters put people together in limited space, where respiratory and gut infections spread more easily. Both shape the ranking below.

How we ranked post-flood germs for Kaeng Hang Maeo

This is WHD's editorial view, tailored to an upstream setting with prolonged water and temporary shelters. It is not a government ranking and it does not use local case numbers. We weighed five criteria:

1. Link to floods: how often the germ appears in post-flood guidance from the World Health Organization (WHO), the US Centers for Disease Control and Prevention (CDC) and Thailand's Department of Disease Control.
2. Severity: how likely an infection is to become serious or need hospital care.
3. Who is at risk locally: older adults, young children, people with chronic illness, and anyone wading or shovelling mud for long periods.
4. Persistence: how long the germ can remain in soil, mud or damp surfaces, described qualitatively rather than with unsupported numbers.
5. Ease of spread: especially where people gather, such as shelters, classrooms and temple halls.

A lower rank does not mean a germ is harmless; the order simply helps families decide what to focus on first.

Post-flood germs ranked for Kaeng Hang Maeo, Chanthaburi: the top 8

No. 1: Leptospira, the cause of leptospirosis

Why it ranks here: Thailand's health authorities warn about leptospirosis after almost every flood. The bacteria come from the urine of rats and other animals and end up in standing water and mud. In an upstream area where water lingers, people wade back and forth to check homes, move belongings or tend animals, so exposure is repeated.

Where it hides: water pooled under raised houses, puddles around the yard, damp mud on kitchen and storeroom floors, and places where rats shelter from the water, such as rice stores, roof spaces and woodpiles.

Symptoms and risk groups: sudden high fever, headache, muscle pain especially in the calves, and red eyes; some people develop yellowing skin or pass little urine. Symptoms can appear from a few days to a few weeks after contact. People with cuts on their feet or legs who wade for long periods are most at risk. If you develop a fever after wading, see a doctor and mention the floodwater.

Prevention: wear rubber boots and gloves, cover wounds with waterproof plasters, wash hands and feet with soap straight after contact, keep food in sealed containers and remove scraps that attract rats.

How cleaning and spraying help: standing water and mud must go first, because no disinfectant works well on a thick layer of mud. Then wash with clean water and detergent. Once surfaces are clean, spraying reaches wide areas and corners that hand wiping misses. Leptospira is a bacterium; CHEMGENE HLD4H product information says it covers bacteria as a group, but we claim no organism-specific result. Ask WHD for test documents if needed.

No. 2: Burkholderia pseudomallei, the soil germ behind melioidosis

Why it ranks here: this bacterium lives in soil and surface water in many regions of Thailand. When heavy rain washes topsoil down from higher ground, soil germs can travel in the mud that enters homes. People shovelling mud or hosing floors can be exposed through cuts, muddy spray or contaminated water. Melioidosis can be severe in people with underlying conditions, which is why we place it high for an upstream district.

Where it hides: flood mud, wet soil around the house, gardens and vegetable plots, farm tool sheds, and boots or shovels that were never rinsed.

Symptoms and risk groups: the illness varies widely, from fever and slow-healing abscesses or wounds to cough, chest pain and bloodstream infection. People with diabetes, chronic kidney disease, heavy alcohol use or weak immunity are key risk groups. A fever that will not settle or a wound that does not heal after mud work needs a doctor's assessment.

Prevention: boots, gloves and a mask when moving mud or using a pressure washer; people with diabetes or kidney disease should avoid direct mud work; clean any wound at once with soap and clean water.

How cleaning and spraying help: the key is to get as much mud out of the building as possible and wash surfaces clean. Spraying afterwards suits indoor surfaces such as floors, lower walls, counters and doors. It is not a way to treat the soil of a whole garden. This organism belongs to the bacteria group the product says it covers, but no organism-specific result is claimed here; ask for documentation if you need it.

No. 3: Norovirus in shelters and shared kitchens

Why it ranks here: with temporary shelters in Kaeng Hang Maeo and Na Yai Am, crowding has to be part of the picture. Norovirus is a major cause of sudden vomiting and diarrhoea wherever people live together. It spreads easily through hands, shared toilets, communal food preparation and frequently touched surfaces.

Where it hides: toilet door handles, taps, handrails, shared dining tables, shared utensils, and blankets or mats taken home from the shelter.

Symptoms and risk groups: nausea, vomiting, diarrhoea, stomach cramps and sometimes a low fever. Watch young children, older adults and people with chronic illness for dehydration; frequent stools, little urine or drowsiness mean it is time to see a doctor.

Prevention: wash hands with soap before eating and after the toilet, keep anyone with symptoms away from food preparation, clean shared toilets often, and wash blankets brought home in hot water where possible.

How cleaning and spraying help: norovirus is one of the organisms listed in CHEMGENE HLD4H product information (according to the product information). Spraying after cleaning therefore suits buildings used as shelters, such as temple halls, meeting halls and schools, before they return to normal use.

No. 4: E. coli and Shigella from sewage

Why it ranks here: floodwater that stays for days often carries waste from cesspits, septic tanks and animal pens. E. coli is the standard indicator that water is contaminated with faeces, and Shigella causes bacillary dysentery. Both spread through hands, food and unsafe drinking water. Households on wells or village water systems need extra care.

Where it hides: kitchen floors, sinks, water jars and storage tanks, the rims of shallow wells, bathrooms where toilets backed up, and children's toys that sat in water.

Symptoms and risk groups: diarrhoea, cramping, sometimes blood or mucus in the stool, and fever. Young children and older adults dehydrate fastest. Bloody stools or high fever need medical care.

Prevention: drink bottled or boiled water until the authorities confirm the supply is safe, throw away food touched by floodwater, wash and disinfect utensils before use, and scrub water jars and tanks before refilling them.

How cleaning and spraying help: after the kitchen and bathroom are washed, spraying helps reduce germs left on floors, walls, counters and bathroom doors. E. coli and Shigella are bacteria; we do not claim organism-specific test results and suggest asking WHD for documents if you need them. Drinking water must be made safe by boiling or by official water testing, never by spraying disinfectant into a water source.

No. 5: Respiratory viruses where people sleep side by side (influenza, RSV)

Why it ranks here: in a shelter the air is humid, people sleep close together and rest is poor. Influenza and RSV spread through coughs and sneezes and through hands that touch shared surfaces. RSV matters most for babies and older adults, while influenza can make people with chronic illness quite sick.

Where it hides: stair rails, tables, plastic chairs, shared toys, light switches and shared blankets.

Symptoms and risk groups: fever, cough, sore throat, runny nose and body aches. Fast or laboured breathing in a young child needs a doctor straight away. Older adults, pregnant women and people with lung or heart disease are at higher risk.

Prevention: wear a mask when unwell, wash hands often, open windows, keep sick people away from babies and older relatives, and ask a doctor about flu vaccination.

How cleaning and spraying help: RSV and influenza (H1N1, H5N1) are listed on WHD's disinfection service page (according to the service information). Spraying a former shelter building after it has been cleaned helps reduce germs left on surfaces before the building is handed back to the community.

No. 6: Wound infections and tetanus risk (Staphylococcus aureus, Streptococcus, Clostridium tetani)

Why it ranks here: cleanup in upstream areas means branches, timber, nails, roofing sheets and broken glass washed in by the water. Small cuts are common. Bacteria from skin and dirty water can make wounds red and full of pus, while deep wounds from soil-covered objects carry a tetanus risk. Anyone injured should ask a doctor about tetanus vaccination.

Where it hides: piles of debris and building materials, the space under raised houses, farm tools that were submerged, and boots that stay wet all day.

Symptoms and risk groups: swelling, redness, heat, pain, pus and fever. Jaw stiffness or muscle spasms after a deep wound need emergency care. People with diabetes and older adults heal slowly and need closer attention.

Prevention: thick gloves and sturdy footwear during cleanup, rinse wounds with clean water at once, keep them covered and dry, and never let a wound soak in floodwater.

How cleaning and spraying help: spraying does not treat wounds and does not replace vaccination. It helps reduce germs on surfaces that people will touch or walk on barefoot after washing. These organisms are bacteria; no organism-specific test result is claimed here.

No. 7: Mold in wooden houses and mattresses (Aspergillus, Penicillium, Cladosporium)

Why it ranks here: water that is "receding but still high" means homes soak longer than in places where floods come and go quickly. Wood, ceilings, plaster, mattresses and fabric hold moisture deep inside. The CDC advises cleaning and drying as quickly as possible, generally within 24 to 48 hours after the water leaves, to limit mold growth. Mold rarely causes acute illness in healthy people, so it sits lower in the list, but it is a real problem for people with allergies, asthma or weak immunity.

Where it hides: behind wardrobes against walls, under wooden floors, in soaked ceiling boards, mattresses and pillows, cardboard boxes and curtains.

Symptoms and risk groups: blocked nose, sneezing, cough, itchy eyes, rashes and asthma flare-ups. People with chronic lung disease or weak immunity should stay away from tearing out moldy materials.

Prevention: discard soaked mattresses, pillows and porous materials that cannot be dried, open the house up, use fans to drive out moisture, and wear a fine-particle mask and gloves when scrubbing mold.

How cleaning and spraying help: product information states the disinfectant covers fungi (according to the product information). Spraying treats surfaces that have been cleaned, but drying must happen alongside it, because mold will return if moisture stays high. For musty air in closed rooms, a residential ozone treatment can be considered as a complementary service.

No. 8: Skin fungi and "water-rotted" feet (dermatophytes, Candida)

Why it ranks here: people who wade in and out of their homes for days, or wear wet shoes all the time, often develop soggy, itchy skin and fungal infections between the toes. It is painful and can let bacteria in.

Where it hides: wet boots, socks, door mats and bathroom floors. Wash and dry feet after every wade.

Symptoms and risk groups: itching, burning, peeling and white, softened skin between the toes. People with diabetes need extra care because foot wounds can worsen.

How cleaning and spraying help: spraying bathroom floors, entrances and barefoot areas after washing reduces fungi on household surfaces, but skin care has to happen on the person, and symptoms should be checked by a health professional.

Why floor cleaner or bleach alone may not be enough

• Bleach is weakened by organic matter and mud. Poured onto a muddy floor, much of its strength is used up on dirt.
• Home-mixed solutions are often too strong or too weak, and bleach must never be mixed with ammonia.
• Hand wiping only reaches what you can reach. Gaps behind cabinets, lower walls, door edges and the space under stairs are often missed.

Effective recovery follows an order: remove mud, wash, dry, then spray with a disinfectant designed for surface disinfection, applied by a trained team.

WHD disinfection spraying after floods for Kaeng Hang Maeo homes and buildings

World Health Disinfection provides disinfection spraying by trained technicians, using spraying and Ultra Low Volume (ULV) fine-mist fogging depending on the space. According to the service information, the disinfectant is CHEMGENE HLD4H, a medical-grade disinfectant from the United Kingdom containing Benzalkonium Chloride and Didecyldimethylammonium Chloride. The service page lists viruses, bacteria and fungi, including COVID-19, RSV, influenza H1N1 and H5N1 and hand-foot-mouth virus, with a claimed 99.99% efficacy, and lists approvals or references from Thailand's Department of Medical Sciences, Mahidol University, NHS England and EN 14476:2013+A2:2019.

The website describes the product as broad-spectrum. We do not quote any number of strains, and for organisms not listed on the website we speak only at the level of the germ group. You can request test documents for a specific organism from the team. Product details are on the CHEMGENE HLD4H disinfectant page.

WHD's office is in Bang Khae, Bangkok 10160, and there is no branch in Chanthaburi. Jobs in Kaeng Hang Maeo and nearby areas are arranged through 065-556-6294 or LINE @whd268. The team asks about area and access, then offers dates based on the schedule. We do not promise same-day arrival, and we only travel once routes are safe and local authorities allow access.

Our five-step process

1. Survey: a phone or LINE consultation with photos.
2. Mud removal and washing first: the owner or a cleaning crew removes mud, discards damaged items and washes surfaces. Spraying never replaces washing.
3. Zoning and preparation: people, children and pets leave the zone to be sprayed; food, utensils and personal items are packed away.
4. Spraying: technicians spray or ULV-fog floors, corners, lower walls, doors, handrails, bathrooms and kitchens.
5. Wait and re-enter: according to the service information, wait about 30 minutes before normal use. Always follow the re-entry time the technicians give on the day, and ventilate before going back in.

According to the service information, customers receive a free CHEMGENE spray bottle and WELLGIENIC wet wipes, and a tax invoice is available.

10 reasons Kaeng Hang Maeo homes and community buildings should be sprayed after washing

1. Long soaking: days of high water mean longer contact with contaminated water.
2. A systematic finish after washing: a disinfection spraying service deals with germs that remain on clean surfaces.
3. Reaches corners hands miss, such as skirting and under stairs.
4. Suited to former shelters: halls and classrooms where many people stayed should be disinfected before normal use resumes.
5. Medical-grade disinfectant: CHEMGENE HLD4H is stated to cover viruses, bacteria and fungi (according to the product information).
6. Less strain on older relatives who would otherwise scrub for hours.
7. Protects crawling and barefoot children.
8. Supports mold control alongside drying.
9. Clear safety steps: people leave the zone and return at the time technicians specify.
10. Easy to arrange from upcountry: call 065-556-6294 or message LINE @whd268 and send photos so the spraying team can assess first.

Before and after: an upstream home that followed every step

Recovery checklist for Kaeng Hang Maeo homes after the water drops

Before going in

• Check district announcements that the route and area are safe.
• Switch off power at the breaker; if floors are still wet, have an electrician check first.
• Wear boots, rubber gloves and a mask, and carry waterproof plasters.

During cleanup

• Remove as much mud as possible, working top to bottom and inside to outside.
• Discard mattresses, pillows and porous materials that cannot be dried.
• Wash surfaces with clean water and detergent, then open the house to dry.
• Clean and disinfect water jars, tanks and utensils before use.

After spraying

• Re-enter at the time the technicians give, and ventilate.
• Keep cleaning high-touch points regularly.
• Watch household members for fever, calf pain, diarrhoea or infected wounds, and see a doctor if they appear.

FAQ: post-flood germs ranked for Kaeng Hang Maeo

Is this ranking from the Ministry of Public Health?
No. It is WHD's editorial ranking based on the criteria above, meant to help prioritise prevention. For official disease information, follow the Department of Disease Control and the provincial health office.

Why is Leptospira number one?
Because prolonged water in an upstream area means repeated wading, and leptospirosis is the illness health authorities warn about most after floods. Fever and calf pain after wading need a doctor right away.

Can I see test results for a particular germ?
Yes. Contact the team to request documents relating to the organism you are interested in.

Come home with confidence and finish the recovery properly

Once the mud is out and the house is washed, let a trained team spray your home, temple, school or community building so everyone can use it again with peace of mind.

See the Disinfection Spraying Service

Call 065-556-6294 · LINE @whd268

Related links and references

• WHD disinfection spraying service: https://www.worldhealthdisinfection.com/en/disinfection-service
• Residential ozone disinfection: https://www.worldhealthdisinfection.com/en/residential-ozone-disinfection
• Public Relations Department, Chanthaburi flood situation, 27 Sept 2026: https://www.prd.go.th/th/content/category/detail/id/33/iid/545378
• CDC flood guidance: https://www.cdc.gov/floods/
• World Health Organization fact sheets: https://www.who.int/news-room/fact-sheets
• Department of Disease Control, Thailand: https://ddc.moph.go.th/