Immunocompromised Patients After a Flood: Protecting Chemotherapy, Dialysis and Transplant Patients at Home from Mold and Waterborne Germs

For most people, mold on a wall after a flood means some sneezing or a blocked nose. For someone receiving chemotherapy, a dialysis patient, or a transplant recipient taking immune-suppressing medication every day, the same mold can cause a lung or bloodstream infection that is life-threatening. Homes with these patients need a higher standard of flood recovery than an ordinary household. This guide is written for relatives and carers. It explains which organisms threaten people with weakened immunity, which warning signs mean going to hospital immediately, how to prepare the home together with the medical team, and where ozone disinfection fits in as the final step before the patient comes home.

A Typical Scenario: A Father on Chemotherapy in Sukhothai, and a House Just Out of the Water

(An illustrative example based on situations we commonly see; it does not describe a specific person or family.)

Uncle Sommai is sixty-two and lives with his daughter Ked in a two-storey wooden house beside the Yom River in Sukhothai. He is in his fourth of six rounds of chemotherapy for lymphoma. When the Yom overflowed and flooded the ground floor to nearly a metre, Ked took her father to stay with an aunt in town while she went back to check on the house every day.

The flood lasted ten days. When the water went down, the ground floor was full of mud, black stains were spreading on the concrete walls, and the ground-floor ceiling panels had swollen and smelled musty. Upstairs, where her father sleeps, stayed dry, but Ked noticed a musty smell drifting up the stairs and mold spots appearing in the corner of his bedroom wall beside the bathroom.

What worried Ked most was the chemotherapy nurse's warning: after each round, her father's white blood cell count would drop very low, and any fever meant coming to hospital immediately. Her father wanted to go home because he felt awkward staying in someone else's house. But Ked was not sure that wiping the walls with bleach and running fans would be enough. If he came home and developed a fungal lung infection or a bloodstream infection, the consequences could be more than the family could bear.

Families face the same situation everywhere: a peritoneal dialysis patient doing exchanges at home in Ubon Ratchathani, a recent kidney transplant recipient in Pathum Thani, a leukaemia patient in Chiang Mai. They all need the same answer: how to make the house safe enough for someone whose body is less able to fight infection.

Who Is Immunocompromised, and Why Floods Are Especially Dangerous

Being immunocompromised means the body's ability to fight germs is reduced, either by the disease itself or by its treatment. Common groups in Thai households include:

• Cancer patients receiving chemotherapy. Many chemotherapy drugs cause neutrophils, a key type of white blood cell, to drop in the days after treatment. During this window the body has almost no front-line defence against bacteria and fungi.
• Kidney patients on dialysis. This includes haemodialysis at a hospital or dialysis centre several times a week and peritoneal dialysis done at home. Chronic kidney failure lowers immunity, and there are entry points for germs such as fistulas, catheters and peritoneal dialysis tubes.
• Organ or bone marrow transplant recipients. They take immune-suppressing drugs continuously to prevent rejection, making infection more likely and symptoms less obvious.
• People on long-term steroids or other immunosuppressants, such as patients with autoimmune diseases, and people whose immunity has not yet recovered from an infection.

1. Airborne mold: the number-one silent threat

A flooded house grows many kinds of mold on walls, ceilings, under floors, in wooden cabinets and in air conditioners. Some molds, such as Aspergillus, are well known in medicine for producing tiny spores that can reach deep into the lungs. A healthy immune system clears them, but in a patient with low white cells or on immunosuppressants, spores can cause a fungal lung infection or spread to other organs. These infections are hard to treat and can be very serious. For that reason, many hospitals pay special attention to dust and humidity control on wards caring for these patients.

2. Bacteria from sewage and mud

Floodwater often mixes with drain and septic tank overflow. Faecal bacteria and moisture-loving bacteria settle on surfaces and inside pipes. Some water and soil bacteria that rarely harm healthy people can cause severe infections in immunocompromised patients, especially through wounds, catheters, or by breathing in contaminated water droplets.

3. Gut infections

Diarrhoea and vomiting from contaminated water or food cause dehydration, which is particularly dangerous for kidney patients and kidney transplant recipients because it affects kidney function. Diarrhoea can also change blood levels of some immunosuppressant medicines.

4. Leptospirosis and infected wounds

Leptospira bacteria from rat urine enter through wounds or skin softened by soaking. Symptoms are high fever, muscle pain, especially in the calves, and red eyes. In kidney patients the disease can worsen kidney function quickly. Immunocompromised people should not wade through water or touch mud at all. A small cut that others would ignore can turn into a spreading skin and tissue infection very quickly in these patients.

5. Interrupted treatment

Floods make it harder to reach dialysis sessions. Medicines and medical supplies may get wet or be lost. Peritoneal dialysis fluid stored on the floor may be ruined by floodwater. Missing dialysis or immunosuppressants for even a few days can be dangerous, so families need to contact the care team as soon as possible to plan together.

Warning signs that need hospital care immediately: fever of 38 degrees Celsius or more, or shivering, especially after chemotherapy; cough, breathlessness or chest pain; diarrhoea or vomiting that stops fluids staying down; unusually low urine output; calf pain; cloudy peritoneal dialysis fluid or abdominal pain; a fistula or catheter site that is swollen, red, hot or oozing; a wound with spreading redness. Contact the care team or go to hospital at once, mention recent flood exposure, and do not wait to see if it passes.

What the Family Has to Carry

Health

For an immunocompromised patient, an infection is not just a few days of fever. It can mean a long hospital stay, a delayed chemotherapy cycle that affects cancer treatment, peritonitis in a dialysis patient, or risk to a transplanted organ.

Money

Treatment for serious infections, antifungal drugs, isolation rooms, temporary lodging near the hospital, and travel to dialysis while roads are still damaged add up to a heavy burden for families already paying for chronic illness.

Time

Carers must juggle taking the patient to treatment, restoring the house and earning a living. When everything happens at once after a flood, exhaustion builds until carers themselves risk falling ill.

Emotions

Many patients feel like a burden and want to go home quickly, while the family fears the house is not safe enough. That tension eases with a clear plan, clear criteria for when the house is ready, and guidance from the medical team.

Why Ordinary Household Cleaning Is Not Enough for These Patients

• Wiping moldy walls with bleach. It kills germs on surfaces it reaches, but scrubbing moldy walls throws spores into the air, and bleach does nothing for spores already airborne or hidden above ceilings and behind cabinets.
• Running fans to dry the house. Fans lower humidity but blow spores through the whole house, including the room prepared for the patient.
• Cleaning only the patient's room. Mold spores travel on air currents, up stairs and through air conditioning. One clean room in a house that still has mold elsewhere is not enough.
• Air fresheners or incense. They mask odours briefly but add irritants to the air, which is unsuitable for weakened lungs.
• Painting over mold. Mold keeps growing under the paint, and fresh paint fumes irritate the airways.
• Bringing the patient home as soon as it looks clean. A house that looks clean may still be damp inside walls and floors, and mold can return within days.

A home for an immunocompromised patient needs a process that reduces both surface and airborne germs, is carried out while the patient is elsewhere, and leaves no irritating chemicals behind for the patient to breathe on returning.

The Answer: Ozone Disinfection by World Health Disinfection

Ozone (O3) is a strongly oxidising gas. Released into a closed space, it spreads into every corner and throughout the air of the room, breaks down the cell structures of viruses, bacteria and mold, and breaks apart odour molecules. It then reverts to oxygen (O2), leaving no chemical residue. Because ozone is a gas, it reaches spores floating in the air and hiding where wiping cannot, which is the weak point of ordinary cleaning.

WHD's ozone service has been tested and certified by Thailand's Department of Medical Sciences and by Intertek (UK), eliminating viruses, bacteria and mold by 99.99% according to the test results certified for the company. We serve homes, condos, hotels, offices, factories, schools and hospitals.

The key principle for homes with immunocompromised patients

Ozone treatment is one part of reducing germs in the environment. It is not a treatment or preventive for disease in the patient, and it does not replace medical advice. Ozone irritates the airways at high concentrations, so it is only ever used in empty spaces. For these patients, we recommend staying elsewhere throughout the strip-out, washing and ozone stages, returning only when every step is complete and the house has been rested and ventilated, and checking the timing with the medical team.

How the process works

1. Survey and prioritise. The team assesses the whole house, mold hotspots and humidity, and prioritises the patient's bedroom, bathroom, kitchen and any area used for preparing medicines or dialysis exchanges.
2. Family or contractor preparation. Mud is removed, soaked materials discarded, swollen ceilings and materials stripped out, surfaces washed and the house dried, with the patient away.
3. Seal and fill. No people, pets or plants may be present. Doors and windows are closed, cupboards and drawers opened, and ozone is released.
4. Contact time. A typical cycle takes about 30 minutes per zone, depending on size.
5. Rest and ventilate. Ozone is allowed to revert to oxygen, then the space is aired.
6. Handover and advice. The team confirms a safe re-entry time and advises on humidity control so mold does not return.

Safety first: ozone treatment is done only in an empty, closed space. People, especially immunocompromised patients, older adults, children and pregnant women, as well as pets and plants, must be out and may re-enter only after the rest and ventilation period. Ozone follows mud removal, washing and drying. It does not replace cleaning, medical treatment or your doctor's advice.

10 Reasons Families of Immunocompromised Patients Choose Ozone Before the Patient Returns

1. Fewer airborne mold spores, a major risk for patients with low white cells or on immunosuppressants.
2. It reaches where wiping cannot, above ceilings, behind cabinets, under beds and inside furniture gaps.
3. No irritating chemical residue. Ozone reverts to oxygen, so weakened lungs are not breathing leftover cleaner fumes.
4. The patient is never present. Every step happens while the patient stays safely elsewhere.
5. Whole-house coverage, not just one room, reducing the chance of spores drifting in from elsewhere.
6. Backed by test results. Tested by the Department of Medical Sciences and Intertek (UK) for 99.99% elimination, according to the company's certified results. See our residential ozone disinfection service.
7. Healthcare experience. The team serves both homes and hospitals and understands why environmental infection control matters.
8. Quick to complete. About 30 minutes per zone, making it easier to align the return date with treatment appointments. Book a treatment.
9. Less worry for carers, with a clear process and confidence that airborne germs have been reduced before the patient returns.
10. Support for ongoing care. Ozone jobs of 15,000 baht or more receive a free medical-grade disinfectant spray for wiping high-touch points after the patient is home. See service details.

Before and After Ozone

Example Case: Wit, a Home Peritoneal Dialysis Patient in Pathum Thani

(An illustrative example to aid understanding, not a verified customer review.)

Wit is fifty-five and has chronic kidney failure. He performs peritoneal dialysis exchanges himself at home several times a day and lives with his wife, Ann, in a townhouse in Khlong Luang, Pathum Thani. When the ground floor flooded to about half a metre, some boxes of dialysis fluid stored downstairs got wet.

The first thing Ann did was call the nurse at the dialysis clinic. She was advised to set aside and not use any bags whose boxes were wet or had touched floodwater, request replacement supplies, and move Wit to his brother's house, which was dry, setting up a clean, dry exchange corner there temporarily.

Meanwhile, Ann hired workers to shovel out the mud, remove swollen skirting boards and an under-stair cabinet, wash floors and walls, and run dehumidifiers for several days. Once the house was dry, she called the WHD team to ozone-treat the whole house, prioritising the upstairs bedroom where Wit does his exchanges and the bathroom. Nobody was inside during treatment. After the rest and ventilation period, the musty smell that used to drift upstairs had dropped noticeably.

Ann wiped down the exchange table and high-touch points again the way the clinic had taught her, stored the new supplies on raised shelving, and brought Wit home after checking with the nurse. They taped a list of warning signs beside the bed, including cloudy drained fluid, abdominal pain and fever, as reminders to go to hospital immediately. Ann's lesson: calling the care team first made every decision afterwards much easier.

Checklist for Families with an Immunocompromised Patient

Call the care team first

• Tell the patient's doctor or nurse the house has flooded, and ask where the patient should stay and when it is safe to return.
• Haemodialysis patients: confirm sessions and find a backup dialysis centre if travel is impossible. Never skip dialysis without telling the team.
• Peritoneal dialysis patients: set aside fluid and supplies that got wet, request replacements, and set up a clean, dry exchange area.
• Transplant recipients: check you have enough immunosuppressants. Never stop them on your own. Report wet or lost medicines immediately.
• Chemotherapy patients: ask which days white cells will be lowest, and plan so the patient is not in an unready house during that window.
• Keep emergency numbers and the patient's medical record book with you at all times.

While the patient stays elsewhere

• Drink boiled or sealed bottled water and eat freshly cooked food.
• Wash hands often and wear a mask in crowded places.
• The patient should not enter the house during cleanup, wade through water, touch mud or garden.
• Take a temperature daily and go to hospital immediately at any warning sign.

Preparing the house before ozone

• Have an electrician check the wiring before turning power on.
• Cleaners should wear boots, rubber gloves and N95 masks.
• Remove mud and discard soaked mattresses, rugs, pillows and upholstered furniture.
• Strip out swollen or moldy ceilings, skirting and plasterboard rather than wiping or painting over them.
• Throw away food that touched floodwater and fridge food from long outages.
• Wash surfaces with soapy water, then disinfect per the label. Never mix products.
• Have air conditioners professionally cleaned and filters replaced.
• Dry the house thoroughly with dehumidifiers and ventilation over several days.

Ozone day and before the patient returns

• All people, pets and plants leave the area.
• Open cupboards, drawers and internal doors.
• Re-enter only after the rest and ventilation time the team gives you.
• Rewash bedding and curtains and dry them completely.
• Wipe high-touch points and medicine or dialysis preparation areas again.
• Keep potted plants and soil out of the patient's bedroom, and ask the doctor about using a HEPA air purifier.
• Check for mold weekly in the first month and call a contractor and our team at once if it appears.

Frequently Asked Questions

1. Can an immunocompromised patient stay home during ozone treatment?

No. Ozone treatment is only done in empty spaces, and we recommend the patient stays elsewhere throughout strip-out, washing and ozone, returning after rest and ventilation and in consultation with the medical team.

2. Will ozone make the house 100% germ-free?

No method makes a house permanently sterile. Ozone reduces viruses, bacteria and mold in the air and on reachable surfaces at the time of treatment, and the company's certified test results show 99.99% elimination. If the house stays damp, mold will return, so humidity control and ongoing cleaning remain essential.

3. Can ozone replace stripping out moldy ceilings or walls?

No. Swollen or deeply moldy materials should be removed and replaced, especially in a home with an immunocompromised patient. Ozone comes after strip-out, washing and drying.

4. Can dialysis fluid or medicines that got wet still be used?

Do not decide yourself. Set them aside and call the care team or a pharmacist immediately. In general, sterile supplies or medicines whose packaging touched floodwater should not be used.

5. What if the patient develops a fever after coming home?

Fever in an immunocompromised patient, especially after chemotherapy, is an emergency. Contact the care team or go to hospital immediately. Do not take a fever reducer and wait.

6. The patient's room upstairs stayed dry. Does it need treatment?

It is worth considering, because spores and humidity travel up stairways and through air conditioning. The team will assess which rooms should be treated.

7. How do we book a survey?

Call 065-556-6294 or message LINE @whd268 and mention there is an immunocompromised patient in the home so the team can plan the work order appropriately, or see other options on our contact page.

Make Home Safe for the People You Love

Talk to World Health Disinfection about a whole-home ozone treatment before a chemotherapy, dialysis or transplant patient comes home.

Book Ozone Before the Patient Returns

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

Related Services and Articles

• Residential and building ozone disinfection
• Disinfection services for buildings and businesses
• Certificates and test results

References

• CDC: Floods and Your Health
• Department of Disease Control, Thailand