Shelters in the 2026 Floods: A Lifeline, and an Easy Place for Germs to Spread

According to a Dailynews report citing the Department of Disaster Prevention and Mitigation (DDPM) at 06:00 on 5 October 2026, floods affected 26 provinces plus Bangkok, a total of 1,270,151 households. Many families had to leave home for temporary shelters, usually in schools, halls, temples, multipurpose buildings or tents on higher ground.

Shelters give people a bed, food and safety. From a hygiene point of view, though, they are a hard situation: many families share limited space and few toilets, eat from one kitchen, sleep side by side on mats or donated mattresses, and many still wade home every day to check on their houses. The World Health Organization (WHO) and other health agencies therefore stress safe water, sanitation and handwashing in shelters.

One sick person in a shelter can pass a germ to dozens of others in a short time. Knowing which germs to watch first, and where they hide, helps shelter teams plan precisely.

Example Case: A School Shelter Facing Diarrhoea and Pink Eye at Once

The following is a typical scenario based on common shelter situations. It does not describe any specific site.

Oy is a teacher who volunteered to coordinate a shelter at a sub-district school. A two-storey classroom block housed a little over a hundred evacuees. Upstairs classrooms became dormitories, the canteen became a kitchen, and a handful of student toilets served everyone. Tap pressure was weak, and some days water came from tanker deliveries.

The first week went well. In the second, several children developed diarrhoea and vomiting, a few older adults had fever and cough, then pink eye spread room by room. Some toddlers had mouth sores, and men who waded home daily complained of itchy, soggy feet. Oy noticed some donated mats and blankets smelled musty because there was nowhere to dry them.

Oy asked the local health promotion hospital to examine the sick and reorganised everything: handwashing points, separating sick people, toilet cleaning, and zoned cleaning and disinfection spraying. Her lesson: in a shelter, germs do not come only from floodwater. They come from many people living together.

How We Ranked Germs in Flood Evacuation Shelters

This is WHD's editorial ranking, not an official or statistical ranking from any agency, and we quote no case numbers or percentages without a source. We weighed:

• Link to disaster settings: how often the germ appears in WHO, CDC and Thai Department of Disease Control guidance for disaster-affected people or shelters.
• Person-to-person spread: people live very close together, so easily transmitted germs score higher.
• Severity for vulnerable groups: shelters hold many young children, older adults, pregnant women and people with chronic illness.
• Link to water, food and toilets: the main weak points of a shelter.
• Persistence: described qualitatively, whether it can last on surfaces, fabrics or bedding long enough to matter.
• Impact on shelter operations: germs that make volunteers ill at once weaken care for everyone.

The order may shift with shelter size, toilets, water source and who is staying there. Shelter teams should always coordinate with local public health staff.

Rank 1: Norovirus and Rotavirus, the Fastest-Spreading Stomach Viruses in Shelters

Why it ranks first: these two are the classic germs of crowded settings, spreading through contaminated hands, food, water and surfaces. Norovirus can infect with very small amounts, and rotavirus is common in young children. With few toilets and awkward handwashing, they move fast.

Shelter hotspots: shared toilets, taps, shared water scoops, door handles, dining tables, trays, drinking water points and anywhere someone has vomited.

Symptoms and who is at risk: sudden vomiting, diarrhoea, stomach pain and sometimes fever. Young children and older adults risk dehydration; drowsiness, little urine or very frequent diarrhoea need a doctor or health officer at once.

Prevention: soap handwashing points near toilets and the kitchen, a separate toilet for people with symptoms where possible, sick people kept out of the kitchen, gloves and correct cleanup of vomit and faeces, and personal cups and plates.

How cleaning and spraying help: norovirus is one of the organisms product information for CHEMGENE HLD4H lists as covered. Zoned spraying of toilets and the kitchen after washing helps reduce repeat outbreaks. Rotavirus belongs to the virus group; ask WHD for specific test data.

Rank 2: Influenza, RSV and COVID-19 in Shared Sleeping Areas

Why it ranks second: sleeping together in classrooms or halls with little space between mattresses, poor ventilation and bodies worn down by stress lets respiratory viruses spread easily. RSV is a particular concern for young children and older adults.

Shelter hotspots: dormitories, registration desks, distribution points, stair rails, dining tables and crowded enclosed rooms.

Symptoms and who is at risk: fever, cough, sore throat, runny nose and fast breathing. Young children, older adults, pregnant women and people with chronic illness face higher risk; breathlessness or persistent high fever needs a doctor.

Prevention: space mattresses where possible, separate sick people, hand out masks, open windows, cover coughs and wash hands often.

How cleaning and spraying help: this group is clearly listed in WHD's service and product information: COVID-19, RSV, influenza H1N1 and H5N1. Spraying dormitories while residents are out, such as during the day, and returning at the time technicians give, reduces germs on shared surfaces.

Rank 3: E. coli and Shigella from Toilets and Unsafe Washing Water

Why it ranks third: with too few toilets, systems can overflow or fill quickly, and some washing water may come from untreated sources. Faecal bacteria such as E. coli and Shigella spread easily. Shigella causes dysentery and can infect with small amounts.

Shelter hotspots: toilets, portable latrines, water drums, scoops, dishwashing points and muddy shoes from wading home.

Symptoms and who is at risk: diarrhoea, cramps, mucus or blood in stool and fever. Young children and older adults are more vulnerable; bloody stool or high fever needs a doctor.

Prevention: bottled or boiled drinking water, separate drinking and washing water, a shoe-off point before sleeping areas, toilets cleaned several times a day, and handwashing after every toilet visit.

How cleaning and spraying help: after washing toilets, spraying reduces bacteria on floors, walls and touch points. Both are bacteria within the group the product covers in general; ask WHD for specific data.

Rank 4: Hepatitis A Virus from Food and Water

Why it ranks fourth: hepatitis A spreads through food and water contaminated with faeces. Its long incubation means people can pass it on before they know they are ill. With one kitchen and many volunteer cooks, shelters need to take this seriously.

Shelter hotspots: the kitchen, chopping boards, utensils, water containers, food distribution points and cooks' hands.

Symptoms and who is at risk: tiredness, poor appetite, nausea, upper right abdominal pain, yellow skin and eyes, dark urine. Adults usually show clearer symptoms than children. Yellow eyes need a doctor.

Prevention: cook food thoroughly, use clean water, keep anyone with symptoms away from cooking, wash hands before food preparation, and ask a doctor about vaccination where appropriate.

How cleaning and spraying help: spraying the kitchen surroundings and food distribution points after cleaning reduces germs on surfaces; direct food-contact surfaces should be washed under food hygiene rules. Hepatitis A is a virus; ask WHD for specific data.

Rank 5: Enteroviruses Behind Hand, Foot and Mouth Disease in Play Corners

Why it ranks fifth: shelters hold many young children who play together all day with shared donated toys. Hand, foot and mouth disease spreads through saliva, nasal mucus, blister fluid and faeces, so it moves quickly among children.

Shelter hotspots: play corners, toys, mats where children sit, nappy-changing spots and children's sinks.

Symptoms and who is at risk: fever, mouth sores and spots on hands, feet and buttocks. Young children are the main risk group; drowsiness, frequent vomiting, refusing fluids or unusual neurological signs need a doctor immediately.

Prevention: frequent handwashing for children, separating sick children, daily toy cleaning and sealed disposal of used nappies.

How cleaning and spraying help: hand-foot-mouth virus is listed on WHD's service page, so spraying play corners and changing spots after cleaning, while children are elsewhere, is very suitable.

Rank 6: Adenovirus Behind Pink Eye, Spread by Hands and Towels

Why it ranks sixth: pink eye is common during floods and in crowded settings. Adenovirus is a major cause of viral conjunctivitis, spread when hands touch eye discharge and then other eyes, and through shared towels and pillows.

Shelter hotspots: towels, pillowcases, taps, washbasins, rails and registration desks.

Symptoms and who is at risk: red, irritated, watery eyes with discharge, sometimes fever or sore throat. All ages can catch it. Severe eye pain, blurred vision or light sensitivity need a doctor.

Prevention: do not rub eyes, do not share towels or pillows, wash hands often, separate people with pink eye and wash their linen separately.

How cleaning and spraying help: spraying shared touch points reduces surface transmission. Adenovirus belongs to the virus group the product says it covers; ask WHD for organism-specific data.

Rank 7: Skin Germs: Staphylococcus, Streptococcus, Skin Fungi and Candida

Why it ranks seventh: many evacuees wade home to check houses or help neighbours. Long soaking softens skin, small cuts come from sharp debris, and bathing is difficult, so foot rot, fungal rashes and bacterial wound infections are common. Soil-contaminated wounds also carry a tetanus risk from Clostridium tetani.

Shelter hotspots: shower areas, wet floors, mats, shared footwear and towels.

Symptoms and who is at risk: itching, burning, peeling, soggy skin between toes, swollen red wounds, pus or fever. People with diabetes need extra care. Spreading wounds need a doctor, and anyone cut by sharp debris should ask a doctor about tetanus vaccination.

Prevention: boots for wading, wash feet with soap and dry them immediately, use powders or creams as health staff advise, and do not share shoes or towels.

How cleaning and spraying help: spraying shower and wet areas after cleaning reduces surface germs. Product information states bacteria and fungi are covered; ask WHD for specific data. Spraying does not replace wound care.

Rank 8: Salmonella from Mass Cooking and Donated Food

Why it ranks eighth: shelter kitchens cook in large batches and receive donated food from many sources. If cooked food sits at room temperature too long or there is not enough refrigeration, Salmonella can multiply, and many people can fall ill together.

Shelter hotspots: the kitchen, chopping boards, food boxes, storage bins, food waste bins and areas with flies or cockroaches.

Symptoms and who is at risk: fever, diarrhoea, cramps and nausea; children, older adults, pregnant women and people with weak immunity are more vulnerable. Bloody stool or high fever needs a doctor.

Prevention: serve freshly cooked food, do not keep cooked food long, separate raw and cooked boards, discard donated food of uncertain safety and clear food waste daily.

How cleaning and spraying help: Salmonella is listed in product information as covered by CHEMGENE HLD4H, so spraying the kitchen, waste points and dishwashing areas after cleaning helps limit its spread.

Rank 9: Leptospira (Leptospirosis) from Wading Home

Why it ranks ninth: leptospirosis does not spread person to person in shelters, so it ranks lower in this setting. But many evacuees wade home daily, and rats may move into shelter areas with food, so the risk stays real. Thailand's Department of Disease Control warns about it in every flood.

Shelter hotspots: flooded paths, food and rice stores that rats can reach, waste points and muddy shoes.

Symptoms and who is at risk: sudden high fever, headache, calf pain and red eyes. People who wade with foot or leg wounds face the most risk. Fever and calf pain after wading need a doctor quickly, mentioning the wading.

Prevention: boots for wading, waterproof dressings, washing feet with soap afterwards, sealed food containers and waste management that does not attract rats.

How cleaning and spraying help: spraying food stores, waste points and entrances after cleaning reduces surface germs. Leptospira is a bacterium; ask WHD for specific data. Spraying does not replace rodent control.

Rank 10: Mold on Mattresses, Mats and Donated Blankets (Aspergillus, Penicillium, Cladosporium)

Why it ranks tenth: in prolonged rain, shelter mattresses, mats, pillows and blankets stay damp with no sun to dry them, and some get wet from rain or from feet coming in from the water. Mold grows easily, causing musty odours and triggering allergies, which worsens existing breathing problems.

Shelter hotspots: foam mattresses, mats, blankets, piles of donated clothes, damp corners and leaking walls.

Symptoms and who is at risk: sneezing, congestion, cough, itchy eyes and asthma flare-ups; older adults, children and people with chronic lung disease should take care.

Prevention: sun-dry bedding when possible, discard moldy items, raise mattresses off wet floors, ventilate, and store donated clothes in dry places.

How cleaning and spraying help: spraying floors, walls and hard surfaces in dormitories after cleaning reduces mold spores; product information states fungi are covered. Heavily moldy mattresses and fabrics should be discarded or washed, not just sprayed.

Summary Table

Why Daily Sweeping and Mopping Alone May Fall Short

Volunteers juggle many jobs, so cleaning is often surface-level. Taps, handles, rails and tables are used all day. Donated cleaning products come in many brands, and mixing them blindly can be dangerous. People are present around the clock, making deep cleans hard to schedule. And when the shelter closes, the school or temple needs confidence before normal use resumes.

WHD Disinfection Spraying for Evacuation Shelters

According to service information, WHD's disinfection spraying service uses trained technicians who spray and/or ULV-fog with CHEMGENE HLD4H, a medical-grade UK disinfectant containing Benzalkonium Chloride and Didecyldimethylammonium Chloride. It is described as broad-spectrum against viruses, bacteria and fungi; the service page lists COVID-19, RSV, H1N1, H5N1 and hand-foot-mouth virus, claims 99.99%, and lists references from the Department of Medical Sciences, Mahidol University, NHS England and EN 14476:2013+A2:2019. Customers include hospitals, schools, offices and residential buildings.

Five-Step Process for Shelters

1. Survey and plan with shelter staff: map toilets, kitchen, dormitories, play corners and food stores, and set times when each zone can be vacated.
2. Clean first: remove mud and rubbish, discard moldy or damaged items, and wash surfaces. Spraying comes after cleaning.
3. Zone and clear people: evacuees, children, older adults and pets leave the spray zone completely; food, medicines and personal items are covered or stored.
4. Spraying: technicians spray and ULV-fog empty zones one at a time.
5. Wait and re-enter: service information says about 30 minutes before normal use; follow the technicians' re-entry time and ventilate.

After a shelter closes, the whole building can be sprayed before returning it to the school, temple or community, and evacuees can book spraying for their own homes after mud removal and before moving back. We do not claim the product leaves no residue, and anyone who is ill should see a doctor.

10 Reasons Shelters and Agencies Choose WHD

1. Built for crowded spaces: reduces germs across many shared surfaces.
2. Medical-grade product: CHEMGENE HLD4H with hospital customers.
3. Clearly listed organisms: norovirus, Salmonella, RSV, influenza, COVID-19 and hand-foot-mouth virus per service and product information.
4. Flexible zoning: no need to close the whole shelter.
5. Short wait: about 30 minutes per service information.
6. Trained technicians: they work alongside volunteers and officials.
7. ULV fogging: even coverage of large halls.
8. Ideal for handover: schools and temples reopen with confidence.
9. Tax invoice available for agencies and organisations.
10. Bonus items: free CHEMGENE spray bottle and WELLGIENIC wet tissues for touch points. See details

Before and After

Example Case: Containing an Outbreak and Returning the School

This example is based on common situations, not a review from a real customer.

After health staff visited, Oy organised volunteers in shifts for toilets, kitchen and dormitories, added handwashing points, set aside rooms for people with diarrhoea and pink eye, and scheduled daytime outdoor activities for each building. Meanwhile the spraying team worked zone by zone after cleaning. When the water fell and families went home, the school deep-cleaned, discarded moldy mattresses and had the whole building sprayed before classes resumed. Parents felt reassured that hygiene was handled step by step.

Shelter Hygiene Checklist

FAQ: Germs in Flood Evacuation Shelters

Can you spray while people are in the shelter?

Not in occupied zones. People leave each zone first and return at the time technicians give, so zoning is planned in advance.

Is this ranking official?

No. It is WHD's editorial ranking based on the criteria above and general WHO, CDC and Department of Disease Control guidance.

Why is leptospirosis only ninth?

In shelters we weight person-to-person spread more heavily. Leptospirosis is still serious: fever and calf pain after wading need a doctor at once.

After spraying, can we skip handwashing?

No. Soap handwashing remains the most important protection; spraying is an extra step that reduces germs on surfaces.

What should a school do after the shelter closes?

Deep clean, discard moldy or damaged items, check toilets and water systems, then spray the building before classes resume.

Can we request test data for germs like adenovirus?

Yes. Contact WHD for data on the organisms your agency is concerned about.

Know the Ranking, Then Let WHD Help Protect Shelters

Ranking germs in flood evacuation shelters tells teams whether to start with toilets, the kitchen or dormitories. Then keep cleaning consistently and spray zone by zone to protect people at their most vulnerable.

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Related Services and References

• WHD Disinfection Spraying Service
• CHEMGENE HLD4H Disinfectant
• Residential Ozone Disinfection
• Dailynews, DDPM flood situation at 06:00, 5 Oct 2026: https://www.dailynews.co.th/news/6249374/
• WHO fact sheets: https://www.who.int/news-room/fact-sheets
• CDC floods: https://www.cdc.gov/floods/
• Department of Disease Control, Thailand: https://ddc.moph.go.th/