A newly published US Centers for Disease Control and Prevention surveillance report, tracking 968 potential cases across four Atlanta hospitals between 2020 and 2024, has delivered one of the most detailed pictures yet of invasive mould disease and its real-world prevalence. Of those cases, 449, or 46 percent, were ultimately classified as genuine invasive mould disease, split across 89 laboratory and clinical-proven cases, 142 laboratory and clinical-probable cases and 218 surveillance cases. Severity among confirmed cases was substantial, with 43 percent requiring ICU admission, 50 percent needing mechanical ventilation and 45 percent dying within 90 days, a figure that climbed to 66 per cent among patients with concurrent or recent COVID-19.
Dr Gavin Macgregor-Skinner, senior director of ISSA’s Making Safer Choices program, described the report as the most detailed active surveillance data seen to date on invasive mould disease, with real implications for how the cleaning and remediation industries assess and communicate risk in water-damaged buildings. “It doesn’t change our protocols,” he said. “This CDC report does strengthen the evidence base we can point to when explaining urgency, scope and risk to building owners, facility managers and healthcare clients.”
Pulmonary infections dominated the clinical picture at 68 percent of confirmed cases, with Aspergillus species responsible for the majority and Aspergillus fumigatus alone accounting for 71 percent of that group. Mucorales genera were more often linked to sinus, nasal and facial infections, while Fusarium species were more commonly associated with cutaneous or deep tissue infections. Macgregor-Skinner noted that this is the first time researchers have had an estimate suggesting invasive mould infections may be an under-appreciated and potentially deadly threat, adding that mould exposure is a recurring problem in the wake of cyclones, storms and floods, and that the scale of the issue may only grow.
Why exposure pathway matters on site
Recognising how a person was exposed, rather than only which species was found, is emerging as a critical piece of risk assessment. “An exposure pathway, whether via inhalation, ingestion or direct contact, determines which fungal genera present the highest health risks by defining how spores and toxins enter the body,” Macgregor-Skinner said. He linked this directly to practical remediation decisions, explaining that airborne dispersal into HVAC systems or occupied breathing zones raises Aspergillus-relevant pulmonary concerns, while standing water or damp materials in direct contact with skin, wounds or medical equipment raise Fusarium and Mucorales-relevant concerns. This distinction, he said, does not change sampling protocol but can help prioritise which findings warrant escalated urgency in a report to facility risk managers.
For Australian operators managing flood-affected buildings, aged care facilities and healthcare sites, two points stood out to Macgregor-Skinner as operationally significant. Clinical risk-tiering by occupant vulnerability remains essential but incomplete, since over a third of confirmed cases had no classic risk factor at all, and the type of mould combined with the exposure pathway is meaningfully linked to different health outcomes. Neither finding changes established remediation protocols, he said, but both strengthen the evidence base professionals can draw on when explaining urgency, scope and risk to clients.
He also flagged a shift in how laboratory identification might be approached on higher-risk jobs. Because non-Aspergillus moulds are individually rare but carry higher antifungal resistance and were linked to distinct infection sites, Macgregor-Skinner suggested that assessments involving extensive contamination or high-risk occupancies may benefit from species-level, rather than genus-level, laboratory identification, where feasible, to give facility stakeholders and treating clinicians a more complete risk picture.
For an Australian cleaning and hygiene industry increasingly asked to justify remediation decisions to insurers, property owners and regulators, this kind of granular international benchmark offers something rare: a rigorous, evidence-based reference point for calibrating exactly when a positive mould finding should sound the alarm, and when it shouldn’t.
