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Aspergillus

What is Aspergillus?

Aspergillus is a group of filamentous fungi found in soil, dust, decaying plant matter, air, building materials and damp environments. (1,2) Most people inhale Aspergillus spores without developing disease. (2) Disease occurs mainly in people with weakened immune systems or underlying lung disease. (1)

Aspergillus fumigatus is the most common cause of human disease, but species within the A. flavus, A. niger and A. terreus complexes also cause infection. (1,3) The World Health Organization (WHO) classifies A. fumigatus as a critical-priority fungal pathogen because of severe invasive disease and emerging antifungal resistance. (4)

National and international perspective

Modelled global estimates suggest about 6.5 million invasive fungal infections and 3.8 million deaths each year, of which about 2.5 million deaths are directly attributable to fungal disease. Over 2.1 million people are estimated to develop invasive aspergillosis annually in the context of chronic obstructive pulmonary disease (COPD), intensive care, lung cancer or haematological malignancy. These estimates are imprecise because of gaps in country-level surveillance data. (5)

In Australia and New Zealand, a 2017–2020 multicentre study of 221 adults with invasive aspergillosis reported 90-day all-cause mortality of 30.3%, and 6.5% of the A. fumigatus sensu stricto isolates tested were azole-resistant. (3) Azole resistance appears uncommon in Australia, but susceptibility testing of clinical A. fumigatus complex isolates is recommended. (6) The Sixth Australian report on antimicrobial use and resistance in human health (AURA) identifies fungal resistance to antifungals as an emerging public health concern. (7)

Epidemiology

Risk is greatest in people with prolonged neutropenia, haematological malignancy, haematopoietic stem-cell or solid-organ transplantation, and high-dose corticosteroid or other immunosuppressive therapy. (1) Chronic lung disease such as COPD, critical illness in intensive care, and severe viral infections including influenza and COVID-19 are also recognised risk settings. (3,5) Invasive aspergillosis without any recognised risk factor is uncommon. (2) However, about 12% of patients in the Australian and New Zealand study had mild or no immunosuppression. (3)

Healthcare-associated infection is sporadic and is associated with dust exposure during building renovation or construction. (1) Demolition, construction and maintenance activities, and mould in the built environment (including HVAC systems), can increase airborne spore counts. Moisture is a key driver of mould growth. (2) Current NSW guidance emphasises building inspection, moisture control, environmental cleaning, HVAC maintenance and construction risk management. (2)

Aspergillus species and forms of disease

Disease ranges from allergic and chronic pulmonary conditions to invasive infection:

  • Allergic bronchopulmonary aspergillosis (ABPA): mainly affects people with asthma, cystic fibrosis or other underlying lung disease. (1,8)
  • Chronic pulmonary aspergillosis: may occur with underlying structural lung disease. (8)
  • Aspergilloma: a fungal ball developing within a pre-existing lung cavity. (1,8)
  • Invasive aspergillosis (IA): occurs mainly in people who are significantly immunocompromised, most often affecting the lungs but potentially spreading to the brain, skin, bones and other organs. (1) It is increasingly recognised in people with mild or no immunosuppression. (3)

How is Aspergillus spread?

Aspergillus is acquired by inhaling airborne spores. Infection is not contagious and does not spread from person to person. (1,2)

In healthcare environments, airborne exposure increases during construction, demolition, renovation or maintenance, particularly where dust, damaged building materials, water intrusion, dampness or compromised HVAC systems are present. (1,2)

Signs and symptoms

Clinical presentation depends on the form of disease and underlying risk.

  • Invasive aspergillosis: fever, cough and chest pain, with shortness of breath and haemoptysis also occurring. Disseminated disease may involve the brain, skin or bones. (1,8)
  • Chronic pulmonary disease/aspergilloma: chronic cough, fatigue, weight loss, breathlessness and haemoptysis. (8)
  • ABPA: wheeze, cough, breathlessness and worsening asthma or cystic fibrosis. (8)

Diagnosis

Diagnosis requires assessment of clinical risk, symptoms, imaging and laboratory findings. Investigations include microscopy, histopathology, culture, galactomannan, β-D-glucan and molecular testing (PCR), alongside CT imaging and respiratory specimens. (1,6,8) Culture and histology remain central to diagnosis, and non-culture biomarker tests are most useful when combined. (6) High-risk patients with suspected invasive aspergillosis need early investigation because of the disease’s high mortality. (2,6)

Australian guidelines recommend susceptibility testing of clinical A. fumigatus complex isolates. (6) European guidelines recommend identifying clinically relevant isolates to species-complex level, with susceptibility testing in invasive disease where surveillance has found resistance. (8) WHO has mapped commercially available and pipeline fungal diagnostics, including antifungal susceptibility testing, and identified gaps and research priorities. (9)

Prevention

Prevention focuses on reducing environmental exposure and protecting people at greatest risk. Because aspergillosis is not spread from person to person, prevention relies on environmental control and protection of at-risk patients rather than isolation of infected patients. (2)

  • Inspect and maintain buildings, HVAC systems, filters and HEPA-filtered areas on an agreed schedule, following manufacturers’ instructions. (2)
  • Promptly identify and remediate water leaks, dampness and visible mould, with escalation for mould in HVAC systems. (2)
  • Undertake an infection prevention and control risk assessment before construction, demolition or renovation. Include a review of air filtration and supply to high-risk areas, and control dust, stagnant water and damp areas. (2)
  • Where possible, provide HEPA-filtered, positive-pressure wards or beds for patients at highest risk. (2)
  • Assess risk and relocate high-risk patients where required. Where a patient at highest risk must be transported near construction, a mask or respirator may be used if tolerated. (2)
  • Identify patients who would benefit from antifungal prophylaxis, and educate patients and families about infection risk, including mould. (2)
  • Conduct at least passive surveillance for proven and probable invasive aspergillosis in units caring for high-risk patients. (2)
  • Routine environmental air sampling is not generally useful. Targeted sampling, for example when an uncommon Aspergillus species is found in clinical specimens, should follow consultation with infection prevention and control, infectious diseases and microbiology. (2)

Treatment and management

Treatment depends on the form and severity of disease.

Invasive aspergillosis requires prompt specialist management with systemic antifungal therapy, and reduction or reversal of immunosuppression where possible. (1,6) Voriconazole is the preferred first-line agent in Australian guidelines. (6) European guidelines list isavuconazole and voriconazole as preferred first-line options, with liposomal amphotericin B as an alternative. (8) The Infectious Diseases Society of America recommends voriconazole as primary therapy, with lipid amphotericin B formulations or isavuconazole as alternatives. (10) Because azole-resistant A. fumigatus is emerging, antifungal susceptibility testing is increasingly important. (1,3,6)

Allergic aspergillosis is usually treated with itraconazole or corticosteroids, and aspergilloma with surgery combined with antifungal medication. (1) Chronic forms require specialist management. (8)

Fungal Disease Awareness Week

The 10th annual Fungal Disease Awareness Week, run by the US Centers for Disease Control and Prevention, was held on 14–18 September 2026. Its daily themes included antifungal resistance and fungal diagnostics and therapeutics. (11)

References

  1. Centers for Disease Control and Prevention. Clinical overview of aspergillosis [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2024 [updated 2024 Apr 24; cited 2026 Sep 9]. Available from: https://www.cdc.gov/aspergillosis/hcp/clinical-overview/index.html
  2. Clinical Excellence Commission. Reducing the risk of aspergillosis in hospitals [Internet]. Sydney: Clinical Excellence Commission; 2026 [updated 2026 Jun 11; cited 2026 Sep 9]. Available from: https://cec.health.nsw.gov.au/infection-prevention-and-control/policies-and-resources/reducing-the-risk-of-aspergillosis-in-hospitals
  3. Tio SY, Chen SC-A, Hamilton K, Heath CH, Pradhan A, Morris AJ, et al. Invasive aspergillosis in adult patients in Australia and New Zealand: 2017-2020. Lancet Reg Health West Pac [Internet]. 2023 Sep 4;40:100888. doi: 10.1016/j.lanwpc.2023.100888
  4. World Health Organization. WHO fungal priority pathogens list to guide research, development and public health action [Internet]. Geneva: World Health Organization; 2022 [cited 2026 Sep 9]. Available from: https://www.who.int/publications/i/item/9789240060241
  5. Denning DW. Global incidence and mortality of severe fungal disease. Lancet Infect Dis [Internet]. 2024 Jul;24(7):e428-e438. doi: 10.1016/S1473-3099(23)00692-8
  6. Douglas AP, Smibert OC, Bajel A, Halliday CL, Lavee O, McMullan B, et al. Consensus guidelines for the diagnosis and management of invasive aspergillosis, 2021. Intern Med J [Internet]. 2021 Nov;51(Suppl 7):143-76. doi: 10.1111/imj.15591
  7. Australian Centre for Disease Control. Sixth Australian report on antimicrobial use and resistance in human health (AURA report) [Internet]. Canberra: Commonwealth of Australia; 2026 [cited 2026 Sep 9]. Available from: https://www.amr.gov.au/sites/default/files/2026-02/sixth-australian-report-on-antimicrobial-use-and-resistance-in-human-health-aura-report_0.pdf
  8. Ullmann AJ, Aguado JM, Arikan-Akdagli S, Denning DW, Groll AH, Lagrou K, et al. Diagnosis and management of Aspergillus diseases: executive summary of the 2017 ESCMID-ECMM-ERS guideline. Clin Microbiol Infect [Internet]. 2018 May;24(Suppl 1):e1-e38. doi: 10.1016/j.cmi.2018.01.002
  9. World Health Organization. Landscape analysis of commercially available and pipeline in vitro diagnostics for fungal priority pathogens [Internet]. Geneva: World Health Organization; 2025 [cited 2026 Sep 9]. Available from: https://www.who.int/publications/i/item/9789240105539
  10. Patterson TF, Thompson GR 3rd, Denning DW, Fishman JA, Hadley S, Herbrecht R, et al. Practice guidelines for the diagnosis and management of aspergillosis: 2016 update by the Infectious Diseases Society of America. Clin Infect Dis [Internet]. 2016 Aug 15;63(4):e1-e60. doi: 10.1093/cid/ciw326
  11. Centers for Disease Control and Prevention. Fungal Disease Awareness Week [Internet]. Atlanta (GA): Centers for Disease Control and Prevention; 2026 [updated 2026 Aug 20; cited 2026 Sep 9]. Available from: https://www.cdc.gov/fungal/fungal-disease-awareness-week/