Guidance for Healthcare-Associated Mold Outbreaks

At a glance

  • Although rare, healthcare-associated mold outbreaks can cause severe illness and death.
  • Even a small increase in mold infections should be reported for public health investigation.
  • CDC offers technical assistance for mold outbreak investigation and response.
Two doctors talking


Invasive mold infections can affect people with weakened immune systems, such as organ or stem cell transplant recipients. Although rare, mold outbreaks can occur in healthcare facilities causing severe illness and death among patients.

Two common types of healthcare-associated invasive mold infections include mucormycosis and aspergillosis. Depending on the organism and patient characteristics, death rates can be more than 50%.



Healthcare facilities can take special precautions to help prevent patients from getting mold infections, including:

  • Filtering the air.
  • Fixing leaks and repairing building damage.
  • Reducing dust during construction.
  • Reducing mold exposure through laundry linens.

For additional protection, patients with high risk for infection may be prescribed prevenatitve antifungal medication and/or placed in positive pressure rooms.

image of a hospital laundry room with text: "Did you know very sick patients can develop mold infections in  healthcare facilitieis? One sources of healthcare-associated mold infections is linen that is damp or left exposued in the environment.
Mold outbreaks have been linked hospital linens.

Outbreak investigation

Health department notification

Notify the local or state health department immediately when healthcare personnel suspect a mold infection cluster. Do not wait for laboratory confirmation to report a cluster or outbreak. Laboratory confirmation for some molds takes longer than it would for many other fungi.

When to suspect an outbreak

Consider reporting and beginning investigations for suspected mold outbreaks if either of the following are observed:

  • A cluster of invasive mold infections above the facility's baseline rate.
  • Cases with onset >1 week after admission.

Confirming outbreaks

Determining whether a cluster of mold infections (i.e., a suspected outbreak) represents a true outbreak can be difficult for several reasons:

  • Diagnosing a case often requires multiple methods (e.g., culture, histopathology, serologic testing, PCR)
  • Case numbers are often small, making it difficult to tell if infection rates are truly above baseline.
  • The incubation period for most mold infections is unclear.
    • Infections beginning > 1 week after admission should be suspected.

Notifying patients

Notify patients at highest risk for severe mold infections as soon as a cluster or outbreak are suspected. Patients at high risk include transplant recipients and patients with hematologic malignancies.

Early patient notification about a suspected outbreak can help:

  • Encourage patients to seek care early if they have concerning symptoms.
  • Build and maintain trust with patients, families, and the public.
  • Educate patients on ways to avoid exposure to mold.

Remind patients, visitors, and clinicians about the importance of proper infection control measures and how to reduce the risk of getting sick.

Patient notification can occur in a number of ways, including verbal communication by healthcare providers based on a healthcare facility–developed template. For more information and examples of ways to notify patients, visit CDC's Patient Notification Toolkit.

Environmental sampling strategy

If performing environmental sampling, a sampling strategy developed by an industrial hygienist who works in healthcare settings is recommended.

Environmental sampling is challenging because mold can be found anywhere. Detecting a certain mold species or level of mold spores in one location or on one object does not by itself indicate that it is the source of infections. Absence of mold in a location or on an object does not necessarily rule it out as mold can be found intermittently and across multiple sources.

CDC outbreak support

CDC works closely with local and state health departments to help identify, investigate, and contain fungal outbreaks. Public health officials, healthcare facilities, and laboratories can request CDC assistance with fungal diagnostics and epidemiologic investigations by emailing

Consultations with CDC on suspected outbreaks can be more effective if the healthcare facility or health department shares a brief summary beforehand.

If possible, summaries should include the following:

  • Information on individual suspected or confirmed cases, as applicable:
    • underlying diseases
    • estimated onset date
    • date and method of diagnosis
    • mold genus and species
  • Facility information
    • locations in the facility infected patients have been prior to infection
    • number of patients with invasive mold infections in recent years, grouped by month of diagnosis.
    • description of any investigation conducted to date.
    • description of any recent construction or demolition activity in or near the facility.
  • Information on specimens still available for further testing.


Investigating mold outbreaks

Laundry management

For infection preventionists to assess laundry management practices at laundry facilities and health care facilities

An article describing strategies to prevent contamination of healthcare linens, which has been linked to healthcare-associated mold infections