Mold After Hurricane Harvey: Immunosuppressed Houstonians Who Cleaned Up Anyway

Summary

• People with weakened immune systems are at risk of invasive mold infections and should avoid exposures like those in hurricane and flood cleanup.
• In a sample of immunosuppressed residents of Houston after Hurricane Harvey, 49% took part in cleaning water-damaged or moldy homes, and few used respiratory protection.
• Health care providers should advise immunosuppressed patients to stay away from water-damaged and moldy areas.

Background

In August 2017, Hurricane Harvey caused unprecedented flooding in the Houston area. Mold was a serious worry: after Hurricanes Katrina and Rita in 2005, flooded homes had grown extensive mold. Mold can cause invasive mold infections, mostly in the lungs, which can kill up to 50% of immunosuppressed patients — so federal agencies advise them to avoid mold-contaminated sites.

The survey

CDC and Texas health officials interviewed immunosuppressed residents from three Houston hospital systems — people who in the past year had a solid organ transplant, or in the last 3 months had been prescribed immune-suppressing drugs such as tumor necrosis factor inhibitors, cyclosporine or chemotherapy. Those whose homes CDC's geospatial models predicted had flooded were called first. None of the hospitals had sent patients system-wide warnings about mold before the storm.

The 20-minute telephone survey, in English or Spanish, ran October 21–November 8, 2017, asking about housing, flooding, mold, cleanup and protective equipment. Of 800 people called, 167 were reached and 109 agreed; 103 who stayed in the area during or after the storm made up the sample. Afterward, participants were given federal guidance on safe mold cleanup for people who are not immunosuppressed.

What was found

• Where they stayed: 75% mostly at home during the storm, 81% since.
• Flooding: 46 (45%) said water got into their homes; for 37, the living space flooded, with a median of 3 inches of water for 3 days. Of those 37, 28 (76%) saw or smelled mold, 32 (86%) had their homes cleaned or remediated, 17 lived there during cleanup, 17 did the cleanup themselves, and 23 planned more within 6 months.
• Cleanup: 50 of 103 (49%) did some — 23 did heavy work (removing furniture, drywall or carpet) for a median of 7 days, and 27 did only light work (sweeping, wiping walls, retrieving belongings) for a median of 4 days.

Only one person wore everything recommended even for healthy people — respirator, boots, goggles and gloves.

• Information: 62 (60%) had heard or read what to wear for mold and floodwater cleanup — most often from television or word of mouth (14 each), and health care providers (7). No one cited a website or social media.

What it means

Many people at high risk of invasive mold infection were exposed to mold and flood damage, and many cleaned up without the protection recommended even for healthy people — gloves were the most common protection. When most homes in a community are damaged, avoiding exposure may be hard; then a proper respirator and other protective gear when going home might reduce it.

Limits: a convenience sample from three hospital systems, not all immunosuppressed Houstonians; participants weren't asked whether a doctor had told them to avoid mold; conditions ranged from rheumatoid arthritis to organ transplants; and healthier patients may have been likelier to take part, perhaps overstating how many did cleanup.

Next steps: doctors should advise immunosuppressed patients to avoid moldy and flood-damaged areas, and future studies of what these patients know and do about protective gear could shape recommendations for when avoidance isn't possible.

Sources

Based on Nancy A. Chow, Mitsuru Toda, Audrey F. Pennington and others, "Hurricane-Associated Mold Exposures Among Patients at Risk for Invasive Mold Infections After Hurricane Harvey — Houston, Texas, 2017," MMWR, Centers for Disease Control and Prevention; a work of the United States government in the public domain.