Environmental Fungi

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 (example in resources below) 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.