Environmentally ubiquitous fungi (e.g., Aspergillus, Mucormycetes) are a cause of invasive infections, especially among immunocompromised persons, that can be associated with substantial morbidity and mortality. Outbreaks of fungal infections among at-risk patients in healthcare settings have been linked to construction, water leaks, insufficient air filtration, non-sterile medical supplies, deficient device reprocessing, dental procedures, contaminated linens, contaminated food and supplements, and other sources of mold spores in the air or on surfaces.

Key Points

• There is no national-level public health disease surveillance for invasive infections with environmental fungi, such as Aspergillus or Mucormycetes, to aid in determining whether disease incidence in a healthcare facility is greater than expected. Approaches to healthcare facility surveillance include reviewing microbiology records for positive fungal culture results, and, if possible, reviewing histopathology specimens with evidence of tissue invasion by fungal hyphae.
• At-risk patients often have complicated medical histories with many different potential sources of exposure, and the incubation period for non-cutaneous infection is not well established; thus, it can be challenging to distinguish colonization from clinical infection and to determine whether exposure occurred within or outside the healthcare facility.
• Investigation is warranted even when it is unclear whether an increase in the number of infections represents a true outbreak, particularly if cases have onset >1 week after admission, appear to cluster in time or place, or occur among patients who share common healthcare exposures.
• Investigation should include an observational environmental assessment (i.e., evaluation of potential environmental sources such as the heating, ventilation and air conditioning system) using a standardized tool performed in coordination among public health, infection prevention, facilities management and engineering, and environmental services staff. Environmental sampling can be difficult to interpret and should only be performed in the context of an epidemiologic investigation and with a predefined sampling strategy.

Featured Resources:

• CDC provides recommended actions for public health and healthcare professionals who suspect a fungal disease outbreak on their Public Health and Healthcare Professionals: Investigating Fungal Disease Outbreaks webpage.
• CDC’s healthcare-associated mold outbreaks page includes resources such as frequently asked questions and an email address for direct consultation and support. About Healthcare-Associated Mold Outbreaks | Fungal Diseases | CDC
• This publication from CDC and Chicago Department of Public Health staff provides an overview of key challenges and response measures related to investigating Mucormycosis in Healthcare settings. The included information may be applicable to other environmental fungi, such as Aspergillus A Guide to Investigating Suspected Outbreaks of Mucormycosis in Healthcare
• This tool is intended to aid in performing an environmental assessment when investigating healthcare-associated disease outbreaks caused by environmental fungi (e.g., Aspergillus spp. and mucormycetes). Not all of sections of this checklist will pertain to every investigation. Where possible, use epidemiologic evidence to guide which sections to complete Targeted Environmental Investigation Checklist for Outbreaks of Invasive Infections Caused by Environmental Fungi
• This sample line list can be used in the investigation of healthcare-associated mold outbreaks.

Additional Resources:

• This article addresses the intricacies and challenges of making patient notifications in the context of hospital-associated clusters of invasive mold infections, with recommended practices Patient notification about suspected hospital-associated outbreaks of invasive mold infections: Considerations for public health and hospital personnel - PubMed (nih.gov)
• This article describes a large outbreak of healthcare-associated mucormycosis that was potentially linked to linens Investigation of a prolonged and large outbreak of healthcare-associated mucormycosis cases in an acute care hospital – Arkansas, June 2019 – May 2021
• This article includes checklists for assessing facility linen management practices Keeping health care linens clean: Underrecognized hazards and critical control points to avoid contamination of laundered health care textiles

For Candida auris please refer to the following CORHA page:

• Candida auris (C. auris)