Mesophilic

Aspergillus fumigatus

Aspergillus fumigatus is the single most important mold pathogen for immunocompromised individuals, responsible for the large majority of invasive aspergillosis cases, a life-threatening lung infection.

Water-damage indicatorMesophilic · Aw ≥ 0.82

Moisture niche · where this species can grow

XerophilicAw < 0.80
MesophilicAw 0.80–0.89
HydrophilicAw ≥ 0.90
Min Aw 0.82
← Drier conditions toleratedRequires liquid water →
Minimum Aw
0.82
EPA reference (GM)
3 SE/mg
Mycotoxin profile
6+ documented
Ecological role
Secondary colonizer

About Aspergillus fumigatus

Aspergillus fumigatus is the single most important mold pathogen for immunocompromised individuals, responsible for the large majority of invasive aspergillosis cases, a life-threatening lung infection with substantial mortality in severely immunocompromised patients. For healthy individuals, spores are inhaled constantly without incident. People undergoing chemotherapy, organ transplantation, high-dose corticosteroid therapy, or living with HIV/AIDS are at materially elevated risk; whether this sample's results are clinically relevant for any specific person is a question for a qualified clinician. A. fumigatus is uniquely adapted among common indoor molds for growth at body temperature (37 °C) and can even grow at temperatures up to 50 °C. It produces gliotoxin, an immunosuppressive mycotoxin that has been detected in the bloodstream of patients with invasive aspergillosis.

Ecology and water requirements

Aspergillus fumigatus is classified as a secondary colonizer with mesophilic moisture requirements: capable of growing at water activity in the range Aw 0.82 and above[2], typical of condensation surfaces and freshly damp materials. Secondary colonizers follow primary xerophilic species in the ecological succession that develops on damp building materials. Detection of elevated Aspergillus fumigatus on an ERMI suggests intermittent or recent moisture conditions consistent with condensation, vapor permeation, or short-lived water events: chronically cool surfaces (uninsulated walls, single-pane windows, plumbing chases) and bathrooms or kitchens with insufficient ventilation are typical contexts.

Mycotoxin biology

Aspergillus fumigatus produces a range of secondary metabolites with biological activity. The compounds documented in the literature for this species are listed in the chips below. Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity[3]. The same isolate may produce substantially different metabolite profiles on drywall paper versus wood versus settled dust[4]. DNA-based detection via the ERMI panel identifies species presence but does not directly measure mycotoxin presence; detection of a mycotoxin-producing species in household dust does not establish exposure to that mycotoxin at any specific concentration.

Detection in dust versus visual inspection

DNA-based detection of Aspergillus fumigatus in settled household dust (the basis of the ERMI panel[1]) integrates spore material from current and recent growth in the home, capturing exposure history over weeks to months. A positive detection in dust does not necessarily indicate currently-active growth at the time of sampling; conversely, an active growth site can produce relatively low dust spore counts if the spores are not being aerosolized (sealed wall cavities, behind vapor barriers, or under flooring). Interpretation requires considering the dust signal alongside building inspection, occupant symptom history, and the broader pattern of species detected on the panel.

Where it’s typically found

Aspergillus fumigatus is documented on the following substrates and locations:

  • HVAC systems
  • compost
  • damp building materials
  • bathrooms
  • kitchens
  • basements
  • potted plant soil
  • humidifiers

Mycotoxins

Compounds documented as produced by Aspergillus fumigatus (presence and quantity vary by chemotype, strain, and substrate):

GliotoxinFumagillinVerruculogenFumitremorgins A/B/CHelvolic acidAsp-hemolysin

Mycotoxin production is not uniform across all strains and is influenced by substrate, temperature, and water activity. Detection of a mycotoxin-producing species in household dust does not directly establish exposure to that mycotoxin at any specific concentration.

On your ERMI report

Aspergillus fumigatus is one of the 26 EPA water-damage indicator species used to compute the SLG1 component of the ERMI score (sometimes labeled "Group 1" in EPA documentation). Whether the level detected in any specific home is concerning depends on the broader pattern: which other species are elevated, the water-activity profile of the elevated species, the home's climate context, and (where relevant) the occupant's sensitivity history. Our interpretation report puts Aspergillus fumigatus in that broader pattern.

Mycotoxins and extended panels

Related reference pages: the mycotoxins Aspergillus fumigatus can produce, and the extended-panel species most closely related to it:

MycotoxinGliotoxinImmunosuppressive ETP-class mycotoxin; this species is the primary indoor route.Extended speciesAspergillus terreusExtended-panel relative; some strains produce gliotoxin.

Related species

Aspergillus flavus/oryzaeAw ≥ 0.78 · XerophilicAspergillus nigerAw ≥ 0.77 · XerophilicAspergillus ochraceusAw ≥ 0.77 · XerophilicAspergillus penicillioidesAw ≥ 0.73 · Xerophilic

References

  1. Vesper SJ, McKinstry C, Haugland RA, et al. Development of an Environmental Relative Moldiness Index for U.S. homes. J Occup Environ Med. 2007;49(8):829–833.
  2. Pitt JI, Hocking AD. Fungi and Food Spoilage. 3rd ed. New York: Springer; 2009.
  3. Nielsen KF. Mycotoxin production by indoor molds. Fungal Genet Biol. 2003;39(2):103–117.
  4. Miller JD, McMullin DR. Fungal secondary metabolites as harmful indoor air contaminants: 10 years on. Appl Microbiol Biotechnol. 2014;98(24):9953–9966.